Three-dimensional bulk reduced graphene oxide coatings with strong metal adhesion via cold plasma and pulsed current

Three-dimensional bulk reduced graphene oxide coatings with strong metal adhesion via cold plasma and pulsed current | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Three-dimensional bulk reduced graphene oxide coatings with strong metal adhesion via cold plasma and pulsed current Zbigniew Zimniak, Włodzimierz Tylus, Beata Borak, Michał Pachnicz, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7741311/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 29 Jan, 2026 Read the published version in Scientific Reports → Version 1 posted 11 You are reading this latest preprint version Abstract Both graphene, a single-atom-thick layer, and its derivative, reduced graphene oxide (rGO), are highly promising materials with a wide range of applications due to their exceptional mechanical, electrical, and thermal properties. However, the application of graphene in its natural form in engineering practice is challenging, which is why a three-dimensional structure is preferred. Additionally, a very strong bond with the metal substrate is highly desirable. Here, we present a method for obtaining such micrometer-thick 3D rGO coatings on various metal alloys. This bulk material coating inherits, to some extent, the exceptional properties of single-layer graphene. The method for obtaining 3D rGO is based on the preliminary preparation of the metal surface using an argon cold plasma and the application of rGO using a pulsed electric current. A good bond between the layer and the substrate has been demonstrated, confirmed both by TEM, where no porosity was found, and in a number of other studies, including XPS, nanoindentation, and scratch testing. To better determine the quality of the obtained bond with the substrate, a resistance measurement method was used during tensile-compression tests. The 3D rGO coating developed can be used in many practical engineering applications where the high strength or other remarkable properties of graphene are particularly desirable. Physical sciences/Engineering Physical sciences/Materials science Physical sciences/Nanoscience and technology Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Introduction Graphene, is a single-atomic-layer material composed of carbon atoms packed in a honeycomb structure of sp 2 hybridized, has been intensively studied because of its extremely physical and mechanical properties with the highest-known intrinsic strength of 130 GPa and a Young’s modulus of 1 TPa [ 1 ]. Its outstanding high strength and elasticity modulus, remarkable electron mobility (15,000 cm 2 V − 1 S − 1 ), super high thermal conductivity (5,000 W·m − 1 ·K − 1 ), high optical transparency and a non-doped sheet resistance of ~ 350 Ohm per square [ 2 – 3 ]. Graphene can be deposited on metals using various techniques, the most common being [ 4 ]: layer-by-layer (LbL), spin coating, spray coating, dip coating, electrophoretic deposition (EPD), dry spray deposition, cold spray (CS), chemical vapor deposition (CVD), and physical vapor deposition (PVD). CVD, a high-temperature process, is the most prevalent method, typically operating between 650°C and 1000°C. Deposition often occurs on Cu, Ni, or SiC substrates [ 5 ]. To reduce the growth temperature of large-area graphene using thermal CVD [ 6 ], a variant with an increased plasma content, known as PECVD, has been proposed [ 7 ]. This method leverages the ability of the plasma to sustain multiple reactive species simultaneously, providing a rich chemical environment. This is the primary advantage of using plasma in such processes, as it facilitates the removal of native oxide and the smoothing of the surface of copper, thus increasing the growth rate of graphene on copper substrates and allowing lower deposition temperatures (< 420°C). The CVD technique has certain limitations, including the need for a high-vacuum system, making it relatively expensive. Additionally, thermally induced strain and topological defects can lead to giant pseudo-magnetic fields and charging effects [ 8 ], consequently diminishing electrical properties. PVD shares similar limitations and further requires plasma technologies. EPD, on the other hand, is user-friendly, cost-effective, and suitable for large, complex surfaces. The methods discussed above typically allow for the creation of single-atom-thick layers on metal surfaces. While such layers exhibit the excellent properties that graphene offers, they present a barrier to practical applications. A solution to this problem is the creation of a three-dimensional graphene-based structure that inherits the best properties of graphene, known as a 3D graphene material. It is important to note that the graphene walls in a 3D graphene material should consist of less than 10 graphene layers. 3D graphene is a crucial material in various engineering applications. However, the production of macroscopic 3D graphene materials remains a challenge in modern nanotechnology. Currently known methods for obtaining a three-dimensional graphene macrostructure include: mild chemical reduction [ 9 ], ice templating [ 10 ], wet-spinning [ 11 ], tape casting [ 12 ], electrochemical construction [ 13 ], laser scribing [ 14 ] and printing technology [ 15 ]. These methods can produce various 3D shapes such as graphene foam [ 16 ], graphene sponge [ 17 ], fibers [ 18 ], millispheres [ 19 ], and others. Many 3D graphene structures are produced directly from GO through a self-assembly method called GO-derived 3D graphene materials, which are usually referred to as 3D rGO. The development of 3D rGO has had a significant impact on its broader use in various composite materials and practical applications [ 20 ]. Another method of obtaining graphene is laser-induced graphene (LIG). This method is one of the most effective ways to prepare porous 3D graphene and has applications in a wide range of electronic devices [ 21 ]. An interesting method is also the three-dimensional patterning of solid microstructures through laser reduction of colloidal graphene oxide in liquid-crystalline dispersions [ 22 ]. In this method, GO flakes and pulsed near-infrared laser were used. Three-dimensional functional solid microstructures of rGO on a glass substrate were obtained. 3D graphene materials hold great promise for numerous practical applications, including batteries [ 23 ], supercapacitors [ 24 ], solar cells [ 25 ], fuel cells [ 26 ], and flexible electronics [ 27 ]. Regarding the application of graphene coatings produced on metals, there are many applications, including potential use in microelectronic devices [ 28 ], sensors [ 29 ], energy storage [ 30 ], and to protect metallic materials from corrosion [ 31 ], reduce wear and friction [ 32 ]. Therefore, a cheap and simple method is needed to deposit a layer of 3D rGO on metals, characterized by good adhesion to the substrate, which is very important for practical engineering applications. This article presents a method for creating a durable bond between rGO and metal alloys at room temperature and atmospheric pressure, resulting in a 3D rGO coating. This two-step method involves the initial preparation of the metal surface using argon cold plasma, followed by a graphene deposition method that leverages graphene's exceptional electrical conductivity. Plasma treatments aim to convert low-energy surfaces to higher-energy surfaces by removing surface hydrogen and introducing oxygen-containing species. In the second step, short, high-current electric pulses are applied to bond the rGO to the metal substrate. This method is cost-effective because it uses graphene flakes, one of the most affordable forms of graphene. Graphene flakes with a few layers are easier to produce in large quantities and offer a greater range of structural configurations due to their corner states, edge states, and diverse shapes [ 33 ]. The bonding mechanism between graphene and metal can vary. Depending on the metal and configuration, it can be weakly physisorbed or strongly chemisorbed on graphene [ 34 ]. For instance, Ag, Al, Cu, Cd, Ir, and Au tend to form physisorbed interfaces with graphene, while Co, Ru, Pd, and Ti tend to form chemisorbed interfaces. Some metals, such as Ni and Pt, can participate in both physisorption and chemisorption with graphene [ 35 ]. Results Preparation To achieve a strong rGO-metal bond, the surface must be pretreated. This is crucial because without it the bond would be insufficiently strong. Ratul Kumar et al. [ 36 ] first observed that cold plasma aids in the process of depositing graphene using the LIG method on a polyimide (PI) surface. The study used contact angle measurement. The surface energy of PI increases with wettability, reducing the activation energy of graphene nuclei diffusion and improving the crystallinity and conductivity of LIG. In our research, cold plasma was used to pretreat the metal surface. Surfaces dominated by carbon-hydrogen (C-H) bonds tend to have low surface energies and thus are less wettable. Surfaces rich in oxygen-hydrogen bonds have higher surface energies and therefore better adhesion characteristics, which were exploited during pretreatment. To bond rGO to the metal, we employed a pulsed current inducing an electroplastic effect (EPE) [ 37 ]. EPE occurs in metals when they are simultaneously subjected to plastic deformation and a pulsed flow of high-density short-duration electric current. A well-known outcome of this effect is a reduction in yield stress and an increase in plastic deformation [ 38 ]. The effect is also used to modify the structural phases of a material to enhance fatigue resistance [ 39 ], reduce internal stresses, and alter the microstructure [ 40 ]. It is generally accepted that the electroplastic effect is due to the force of the electron wind exerted by the electrons on dislocations within a crystal [ 41 ]. In our work, we exploited the high electron velocity in graphene (where charge carriers behave like relativistic particles [ 42 ]) to amplify the electroplastic effect. This results in plastic deformation occurring at lower applied forces [ 43 ]. The method we developed for creating durable bonds between rGO and metal alloys involves an initial surface treatment using an atmospheric pressure plasma jet (APPJ). A thin layer of graphene flakes is then deposited, followed by a pulsed electric current process to permanently bond the graphene layer to the metal substrate (Fig. 1 ). The thickness of the graphene layer depends on the deposition method and can range from a few nanometers to several micrometers. In the first stage, the metal surface is pretreated. To this end, the surface is cleaned with ethyl alcohol, then sanded with 120 grit sandpaper and polished with a diamond polishing pad using a grain size of 9 µm grain size. Finally, a polishing cloth with a 3 µm diamond paste is used. The maximum roughness of the polished surface did not exceed R a = 0.8 µm. This preliminary surface preparation step is not always necessary; it is sufficient to use the material as supplied if it has an appropriate roughness. In the next stage, the prepared surface is activated using a low-temperature argon plasma generation device. Plasma treatment is carried out for 120 seconds. The effect of plasma treatment is a significant increase in the surface free energy of the metal. The atmospheric pressure plasma jet system consists of a plasma head, which is composed of a negative electrode, a positive electrode, a dielectric located between them, and a gas supply system and a high-frequency voltage supply system for the plasma head. During low-temperature plasma generation, the plasma head is held at a distance of two centimeters from the surface of the metal being processed. If the surface of the metal being processed is large, a reciprocating motion of the plasma head should be applied to cover the entire surface of the metal being processed. A self-made atmospheric pressure plasma jet system with the following parameters was used: power 300 W, operating voltage 18 kV, operating frequency 25 kHz, argon flow rate 16 l/min, and constant exposure time of 120 seconds. During plasma treatment, the maximum temperature measured with a thermal imaging camera was 31°C. Next, the metal surface on which the low-temperature atmospheric plasma was generated is coated with rGO flakes by using a dry method, collecting its excess to a specific thickness or wet, using graphene in the form of a solution in vinyl alcohol. Electropulse treatment involves pressing a copper electrode with appropriate force onto the rGO layer on the metal, while simultaneously supplying a pulsed current from a power supply with a current of 1.9 kA. Positive rectangular current pulses with a duration of milliseconds were used. The pulsed current was supplied to the treated layer through an electrode with a tip size of 3x3 mm, pressed with a force of 20 N. The process is scalable; by replicating it, a larger surface area can be covered. Current pulses were delivered from developed current pulse generator equipped with a 1400 F supercapacitor battery and a current switch implemented using a MOSFET matrix. The current was generated in the form of a function generator in the form of t d / t p , where td is the duration of the pulse and t p is a period. The power supply operating voltage was 2.55 V. As a result of this 3-second electropulse process, a permanent bond was formed between the rGO flakes and the metal substrate. In the study, a sample of Titanium Grade 2 in the form of a 2 mm thick sheet was used. To determine the influence of electropulse parameters on the final coating thickness, experimental investigations were conducted across varying current pulse durations (td), while maintaining a constant pulse period (tp) of 1000 µs. A direct correlation was observed: as the pulse duration increased, the thickness of the resultant 3D rGO coating exhibited a successive increase. The duration of the experimental current pulse t d was determined to be 500 µs and the time t p was 1000 µs, respectively. The process temperature measured with a thermocouple placed as close as possible to the edge of the electrode was 950°C. This is a much higher temperature than that obtained in a typical electroplastic process, because rGO has good electrical conductivity. Structural characterizations To characterize the structure of the rGO flakes used and the prepared layers on the Ti Grade 2 substrate, TEM analysis was performed using a Hitachi H800 microscope. A suspension of the powder in acetone was deposited on copper carbon grids and left to dry. The microstructure of the coatings was analyzed on Ti samples prepared by the FIB (Focused Ion Beam) method. Cross sections were obtained in two directions, parallel to the coating and substrate (orientation A) and perpendicular (orientation B). The results obtained were compared and analyzed to confirm the graphene phase using selected area electron diffraction (SAED) patterns. Using the Kat.Dyfr program, theoretical electron diffraction patterns were obtained for parameters defined according to the Pearson catalogue [ 44 ] (a, b, c, α, β, γ), which were then compared (overlapped) with the recorded images. The figures show a general view of the material under investigation observed in a Hitachi H800 microscope. The analysis of the particles showed that the rGO flakes varied in shape and size (Fig. 2 a). Electron diffraction patterns were obtained from the visible areas. Very good agreement was found both in terms of the defined interplanar distances and interplanar angles with the theoretical values. Differences in the determined values were below 0.001 nm and resulted from the measurement method used. Furthermore, it was found that the orientation of the graphite flakes recorded and the zone axis indices are as follows [uvw] = [100]. The results obtained confirm the presence of graphene in the investigated material. Figure 2 b shows a view of the deposited rGO layer on the analyzed sample. The microstructure of the rGO coatings was analyzed in two cross sections, perpendicular to the coating and substrate, and parallel to the substrate (orientations A and B). Microstructure studies revealed a compact, granular structure of the rGO coating, exhibiting strong adhesion to the substrate (Fig. 2 c). Furthermore, a fragmented structure of the substrate material was observed, marked by white lines in Fig. 2 c. The coating exhibits a compact, dense, and pore-free structure with high adhesion to the substrate. Microstructure analysis performed on a cross-section of the coating revealed grains of varying sizes in the bonding zone, indicating changes in the substrate material as a result of coating deposition. The dominance of grains with oval and spheroidal crystal structures was observed (Fig. 2 d). Depending on the direction of study, the formed coating exhibits different crystallographic orientations of the grains. In the cross section of the coating made in the second direction (orientation B), a plate-like structure dominates (Fig. 2 e). The presence of individual graphene flake packages was observed (Fig. 3f). On the basis of the analysis of the recorded diffraction patterns, a very good agreement was found, both in terms of the defined interplanar distances and interplanar angles, with the theoretical values for the graphene phase. The studies confirmed the presence of graphene in the investigated coatings. A dense and pore-free 3D rGO coating was obtained, which showed strong adhesion to the substrate. This is attributed, among other factors, to the high temperature experienced by the thin rGO layer during the process. The observed microstructure of the coating in the analyzed cross sections revealed that most of the rGO flake packages were oriented perpendicular to the observed surface. This orientation is a direct result of the deposition method, where the electric field acts on the rGO flakes in this particular direction. Investigations of the metal surface condition after plasma treatment process To assess the surface condition before and after plasma treatment, contact angle measurements were performed using the sessile drop method. This technique evaluates the interaction and spread of a test liquid droplet (Supplementary Table 1). Figure (Supplementary Fig. 2) shows a water droplet deposited on a Ti Grade 2 surface. The contact angle of the material in the received state of 74° indicates a certain degree of hydrophilicity of the substrate. As a result of plasma treatment of the Ti surface, a higher wettability of the substrate was achieved by water, with a contact angle of 43°. Additionally, Surface Free Energy (SFE) was calculated to assess the efficiency of cold plasma treatment. As shown in Supplementary Fig. 3, cold plasma treatment significantly increased the polar fraction of the SFE, resulting in an overall increase in the surface free energy of the tested specimen. This significant increase in the polar fraction of the SFE, approximately 100%, indicates an increase in the hydrophilicity of the surface exposed to low-temperature plasma, making it more reactive. The action of the active plasma likely resulted in surface cleaning by breaking the bonds of organic contaminants, which were subsequently oxidized and removed. The significant increase in the polar component of the surface free energy likely correlates with an increase in surface oxygen content. This is likely the primary factor contributing to the observed differences in surface energy between the untreated and plasma-treated specimens. To further investigate the factors contributing to the observed differences in surface free energy, X-ray photoelectron spectroscopy (XPS) was employed to analyze surface chemical changes induced by plasma treatment. Characterization of the 3D rGO coating XPS was used to monitor the successive stages of rGO coating formation on the Ti Grade 2 surface. Surfaces rich in oxygen-hydrogen bonds exhibit higher surface energies, leading to improved adhesion. The primary objective of the XPS analysis was to investigate how plasma treatment of the titanium surface influences its initial adhesion and subsequent deposition of a robust graphene coating. In the first step, XPS was used to assess the effectiveness of low-temperature plasma beam treatment (with specific parameters) on the Ti Grade 2 surface, immediately prior to graphene deposition. In the second step, XPS was used to characterize the deposited carbon layer, specifically to determine its graphene-like nature. XPS is a surface-sensitive, nondestructive analytical technique with high surface sensitivity. For example, the average inelastic mean free path (IMFP) for Ti 2p electrons in TiO 2 is 1.7 nm, while in C/CxOy layers it typically does not exceed 2.3 nm [ 45 ]. Therefore, the sampling depth (3λ) and the calculated elemental composition will always apply to layers with thicknesses < 8 nm (assuming the homogeneity of the analyzed layer). Substrate pretreatment. Plasma cleaning. Table (Supplementary Table 2) presents the chemical composition of the Ti surface, mechanically pre-degreased and ground, before and after plasma beam exposure. Analysis revealed that both the raw and ground metallic Ti surfaces were covered by a layer of natural oxides, primarily composed of carbon (including oxygen-bound carbon) and titanium oxides. Nitrogen and calcium were also found on the surface of both samples. As suspected, mechanical grinding did not expose the metallic surface. The total elemental carbon content decreased slightly, from approximately 58 to 54 at. %, and the C: Ti ratio from 5.3 to 4.6, respectively. The general degree of surface oxidation did not change, O:Ti = 2.6. The deconvolution of the C 1s spectra, presented in Fig. 3, revealed that the carbon bonding structure on the Ti surface before and after grinding was very similar, characteristic of a typical native passive coating on metallic titanium (Supplementary Table 2) [ 46 ]. UV light and active oxygen species (radicals), generated within the atmospheric plasma, effectively disrupted the C-C(H) bonds of surface contaminants. After irradiating the Ti surface with a plasma beam, the total surface carbon content considerable decreased to about 16% at. (3.4 times). The bonding structure also underwent changes. The proportion of C-C(H) bonds decreased from 66% to 27%, while the abundance of oxygen-containing bonds increased. The fractions of C-O and C-O-H (13.1%), C = O and O-C-O (9.7%), and O-C = O (10.8%) were not substantially different from those observed in 'native' oxides on the Ti surface. However, two new forms of active surface oxygen emerged: CO2 (ads) (16.7%) and CO3-/O-C(O)-O (22.3%), with binding energies of 289.6 eV and 292.7 eV, respectively [ 47 ]. Although the elemental composition, as presented in Supplementary Table 2, represents the composition of layers only a few nanometers thick, it does not significantly reflect variations in the depth profile of these layers. The structure of the existing and newly formed carbon and oxide layer was modelled using QUASESTM analyze software for the excitation of Mg Kα [ 48 ]. The results of the modelling for the plasma-modified Ti surface are presented in Fig. 3. In the initial step, the thickness of the overlayer, primarily composed of adventitious carbon, was determined by analyzing the Ti 2p region (Fig. 3d). The depth at which carbon and its compounds appeared was independently estimated based on the Auger C KLL region (Fig. 3e). Subsequently, the thickness of the oxide layer was modelled with 'Analyze' using the Auger OKLL region of the Mg Kα survey (Fig. 3f). The resulting carbon/oxide layer profile is illustrated in the bar diagram: the thickness of the TiO 2 (+ TiO + Ti 2 O 3 ) layer was estimated to be 3.5 nm (at a depth of 1.5 to 5.0 nm). The outermost layer consisted of a 0.5 nm thick layer of contamination carbon (C-C/C-H) overlaid by COx bonds (1.5 nm). Given the high reactivity of Ti, it is highly probable that some of this carbon adsorbs onto the Ti surface even after plasma beam irradiation. Within a depth of 1.5 to 2.2 nm, both titanium oxides and COx groups were present in the modelled layer. The exact structure of the Ti bonds is depicted in Fig. 3. The figure shows high-resolution Ti 2p envelopes with their deconvolutions for the ground and degreased titanium surface (Fig. 3g) and after plasma beam irradiation (Fig. 3h). The fitting parameters for the Ti 2p peak were determined using averaged binding energy (BE) data and splitting data of 2p 1/2 − 2p 3/2 from the NIST XPS database [ 49 ]. Furthermore, data from readily available standard samples (metal, TiO 2 ) [ 50 ] were used to refine peak widths, splitting (Δ = 6.05 eV for Ti(0), Δ = 5.72 eV for Ti(IV)), and shapes (asymmetric for the metallic component). The best fit was achieved by deconvoluting the Ti 2p spectrum into four components: TiO 2 , Ti 2 O 3 , TiO and Ti(0), with Ti 2p 3/2 binding energies of 458.6, 457.2, 455.5, and 453.7 eV, respectively. A comparison of the Ti spectra before and after plasma beam irradiation reveals an increase in the overall oxidation state of Ti. The proportion of TiO 2 increased from 64.5% to 76.3%, while the fractions of other forms of Ti decreased: Ti 2 O 3 from 15.0 to 10.5%, TiO from 5.1 to 3.8%, and Ti(0) from 15.4 to 9.3%. Considering that Ti(0) resides beneath the TiO 2 layer, it is evident that plasma beam irradiation of the Ti surface resulted in a significant reduction in carbon contamination and an increase in the oxide layer thickness from 3 nm to approximately 5 nm (Fig. 3), primarily consisting of TiO 2 . Testing of the deposited 3D rGO layer Immediately after plasma treatment, a layer of flake rGO was deposited onto the Ti surface using the procedure described above. XPS studies revealed that the actual substrate for graphene deposition was a TiO2 layer (rather than metallic Ti), at least 3 nm thick, overlain by a strongly adsorbed outermost layer of CxOy groups, estimated to be an additional 2 nm thick (Figs. 1 and 2 ). Figure 4 presents C 1s spectra for a Ti surface coated with a graphene layer, using the method described in this work. Reference spectra of the reduced GO used in this study, as well as commercial graphene (PCC Rokita), are also included. These reference samples helped identify carbon-carbon and carbon-oxygen bonds within the resulting layer. Graphene, along with other graphitic materials, exhibits a distinct main C 1s peak attributed to C = C, serving as a valuable reference. This peak is often assigned an energy of 284.5 eV. The binding energy of this peak is approximately 0.5 eV lower than that of aliphatic/contamination bonds (C-C, C-H). To ensure compatibility with previous studies in which the C 1s peak for carbon contamination at 284.8 eV was used as a reference energy, the C 1s binding energy for graphene (C = C) was set at 284.3 eV. The table (Supplementary Table 3) presents the fitting parameters for graphene and graphene-type materials, including the main peak asymmetry and π to π* shake-up satellite from a standard pure graphene / graphite sample. The deconvolution procedure was adapted from Biesinger's excellent work [ 50 ], and the parameter values were refined on the basis of an owned spectrum (Fig. 4 a) of commercial flake graphene (PCC Rokita). In Figs. 4 b and 4 c, the C 1s spectra are shown for the flake rGO used in this work and the Ti surface, with the carbon coating deposited, and again using the deconvolution parameters shown in Table 3. To correctly position the C 1s spectrum for Ti with an applied carbon layer, BE 458.6 eV for Ti 2p 3/2 for an uncoated TiO 2 /Ti substrate after plasma irradiation was used as a reference (Fig. 3g). Analyzing the results shown in Fig. 4 , it was found that for the parent rGO, the total degree of oxidation/decomposition of its graphene monolayer structure, measured by CxOy / (C = C + sat), was 25% (versus 8% for pure commercial graphene). Exactly the same degree of oxidation/defect, characteristic of the rGO used, was calculated for the carbon layer obtained deposited on the Ti surface. Moreover, the position of the maximum dominant C 1s peak at 284.3 eV and its characteristic asymmetry are additional arguments that confirm that the obtained coating on Ti has a graphene (or more precisely, rGO) structure. In the C1s region, the presence of C-C and C-H bonds should also be noted. Although its share in rGO was only about 3%, on the rGO / TiO2/Ti surface analyzed, this share increased significantly to 33%. The XPS analysis revealed that at atmospheric pressure, low-temperature plasma treatment effectively removes the carbon content derived from contaminants on the material surface. Under atmospheric pressure, low-temperature plasma, high-energy ions collide with the sample surface, dissociate the carbon bonds in the contaminants, and cause them to volatilize. Characterization of the 3D rGO by Raman spectroscopy To determine whether the 3D rGO deposition process caused significant changes in the structure of the original rGO, Raman spectroscopy was used. Raman spectroscopy is a powerful and nondestructive technique for characterizing graphitic materials such as graphenes, fullerenes and carbon nanotubes, and is also useful for distinguishing between pristine graphite, GO and rGO [ 52 , 53 , 54 , 55 ]. In this study, Raman spectroscopy with a laser excitation wavelength of 514.5 nm was used to analyze the formed 3D rGO layer on Titanium Grade 2 (Fig. 5 ) and other different metallic supports (Supplementary Fig. 4). The Raman spectra of graphitic materials appear simple, they consist on a couple of very intense bands in the 1000–2000 cm − 1 region and few other second-order modulations [ 52 , 54 , 56 , 57 ]. The GO and rGO spectra are characterized by two intense bands: D and G, but they differ slightly in position and intensity [ 53 ]. The G band represents the vibration mode in the plane of sp 2 -hybridized carbon atoms (the E 2g phonon of C sp 2 atoms) and is characteristic of all samples containing sp 2 carbon networks [ 52 , 53 , 57 , 58 ]. The D band at 1363 cm − 1 is associated with structural defects and disorder in graphene structure (rings of the graphene layer) and indicates a reduction in the size of the sp 2 domains in the plane, e.g. due to extensive oxidation [ 52 , 56 , 57 , 58 ]. Graphene with an ideal structure does not show D band [ 57 ]. The ratio of the D and G band intensity (ID/IG) is a measure of the amount of disorder present within the material and is used for characterizing the defect quantity in graphitic materials [ 52 , 53 , 59 ]. Graphitic materials also exhibit a Raman band in the 2500–2800 cm − 1 range. This band, known as the 2D band, corresponds to the overtone of the D band [ 52 , 56 ]. As shown in Fig. 5 , the Raman spectrum of rGO exhibits a D-band at 1357 cm − 1 , a G-band at 1597 cm − 1 , and three broad bands with low intensity in the 2500–2850 cm − 1 range. The position of the D-band remains unchanged after the deposition of GO powder on Titanium Grade 2 (Fig. 5 ) and other metallic support (Supplementary Fig. 4). The G band shifts slightly (from 1357 cm − 1 to 1603 cm − 1 ) after deposition and this is observed for all samples tested. Larger band shifts are observed for rGO deposited on NiCr wire. In this case, the D band shifted from 1357 cm − 1 to 1416 cm − 1 and the G band shifted from 1597 cm − 1 to 1655 cm − 1 . This may be due to a different rGO coating deposition process. No G-band splitting was observed in any of the tested samples, which may indicate that rGO was not affected by randomly distributed defects [ 57 ]. The I D /I G intensity ratio for the D and G-bands is widely used to characterize the quantity of defects in graphitic materials [ 52 ]. The ID/IG intensity ratio correlates with the average size of the sp 2 domains and is frequently used to compare the degree of disorder and the size of the crystallite in graphitic layers [ 55 , 58 , 59 , 60 ]. For GO samples, the intensity of the G band is typically higher than that of the D band. When GO is converted to a graphene network, the I D /I G intensity ratio increases as the sp 2 carbon network forms [ 58 ]. In the rGO spectra and the prepared sample of rGO deposited on the Titanium Grade 2 and other support, the ID/IG intensity ratio of the rGO is higher than 1. The deposition process has no significant effect on this value. Due to their broadness and low intensity, it is challenging to discern changes in the position of the bands in the 2500–2850 cm − 1 range. The intensity of the 2D band is low compared to the D and G peaks. The shape of the 2D band is strongly dependent on the number of graphene layers in the sample, allowing Raman spectroscopy to differentiate between samples with a small number of sheets (1, 2, or more) [ 52 , 54 ]. The G peak and another peak, called the G' band, which appears at approximately 2700 cm − 1 , are characteristic of monolayer graphene in Raman spectra [ 56 ]. An increase in the number of layers leads to a significant decrease in the intensity of 2D peaks, as observed in the prepared samples. Since the I 2D /I G intensity ratio is less than 1 for all samples presented, it suggests a multilayered graphene structure for both the initial rGO and after its deposition on metallic supports [ 54 ]. Based on these observations, we can conclude that no significant reduction or other significant process occurred during the deposition of GO powders onto metallic supports. The structure of the GO powder remains unchanged, indicating that oxygen functional groups from the rGO are not removed during the deposition process. Mechanical properties of the 3D rGO layers To characterize the mechanical properties of the produced layer, nanoindentation tests were performed on a sample of WCLV tool steel coated with 3D rGO. Nanoindentation is a widely recognized technique for evaluating the local mechanical properties of thin coatings by observing the force-displacement behavior during the penetration of a diamond indenter with a defined geometry into the material’s surface [ 61 – 62 ]. The test provides key parameters such as hardness and indentation modulus, which reflect the material’s ability to resist deformation and elastic recovery, respectively. Given the heterogeneous nature of the 3D rGO coating, the Grid Indentation Technique (GIT) was employed [ 63 – 64 ]. The indentations were spatially targeted to a well-defined region of the 3D rGO layer deposited on WCLV tool steel. The target region was optically and morphologically identified prior to testing (Fig. 6 a). A matrix of indentations was applied exclusively within the confirmed coating area to ensure that the derived mechanical properties reflect the intrinsic behavior of the rGO architecture. The tests were conducted using a Berkovich indenter under depth-controlled indentation, with maximum penetration depth set at 200 nm and indent spacing of 10 µm (center-to-center). The selected maximum depth ensures that the influence zones of adjacent indents remain non-overlapping, preserving the statistical independence of measurements. The indentation depth was also selected to probe predominantly within the coating volume, given its thickness in the micrometer range. Figures 6 b and 6 c show contour maps of the spatial distribution of the indentation modulus (E IT ) and hardness (H IT ), respectively. These maps reveal a distinct mechanical response across the coating, with a central region displaying elevated mechanical properties—consistent with effective flake alignment and densification. Peripheral zones showed slightly reduced values, suggesting microstructural heterogeneity, possibly related to variation in local flake orientation or layer thickness. The statistical correlation between hardness and indentation modulus is plotted in Fig. 6 d. The majority of measurements cluster around values consistent with dense rGO-based architectures (E IT = 200–400 GPa; H IT = 10–30 GPa), but several data points display extreme values, with E IT exceeding 500 GPa and H IT approaching 45 GPa. These outliers likely correspond to localized domains of well-aligned, few-layer rGO flakes, what also aligns with values reported in the literature for high-quality graphene layers [ 65 – 66 ]. Histogram insets illustrate the distribution of mechanical properties, confirming a non-Gaussian distribution skewed toward high-modulus and high-hardness tails. Testing the adhesion of 3D rGO to substrates Beyond evaluating the mechanical properties of the 3D rGO layer, an additional objective was to assess the adhesion of the graphene coatings produced to various metal surfaces. The testing protocol involved performing 1 mm-long scratch tests on three different samples: titanium Grade 2 (Ti), ASI 304 (SS)stainless steel, and tool steel (WCLV). During the tests, a constant normal force of F N =2000 mN was applied. Additionally, for the titanium sample, a sequential scratch test was conducted to determine whether repeated passes of the indenter would cause delamination of the graphene from the substrate. Scratch locations were chosen along the boundary between the 3D rGO coating and the substrate material for all samples. Detailed panoramic images of the tested areas are shown in Figs. 6 a-c. The scratch direction was set from the 3D rGO-coated surface towards the bare substrate. Upon completion of the initial analysis, it was observed that in none of the cases graphene flakes were visibly detached from the surface, indicating a good adhesion between the 3D rGO coating and the tested substrates. In the case of stainless steel, a slight residue of graphene was visible on the underlying surface. No cracks or defects were observed in the 3D rGO layer in the initial stages of the scratch test. The surface of WCLV shows a smoother transition during the scratch test, indicating a better resistance to deformation or delamination under these conditions. For the sequential scratch test, the procedure involved the performing of 18 successive scratches of 800 µm length, applying a constant normal force of F N = 500 mN, along a predefined measurement path. As in the previous tests, the scratch path was positioned at the boundary between the 3D rGO coating and the titanium substrate. Each successive pass of the scratch tester began at the same starting point, allowing for the observation of changes in the penetration depth of the indenter. These changes were influenced solely by the evolving mechanical properties of the surface, excluding the effects of the surface morphology. The selected area and longitudinal scratch profiles are shown in Fig. 6 d. Figures are presented in a scale that identifies the "transition point" from the titanium surface to the 3D rGO coating at X = 0.34 mm. Furthermore, variations in the penetration depth with successive passes are recorded and displayed in the accompanying figure (Fig. 6 e). The increase in both frictional forces (orange) and penetration depth (black) is evident once the scratch tester transitions from the titanium substrate to the 3D rGO coating at X = 0.34 mm. The lack of significant penetration or delamination during subsequent passes suggests that the 3D rGO layer effectively resists wear, maintaining strong adhesion throughout the test. The presence of graphene after scratch tests was also confirmed by Raman spectroscopy. Figure 8 shows the Raman spectra measured for the WCLV steel sample in different places: in the test trace (Fig. 8 ) A and B areas scratched, C area - not damaged during the test. The first observed difference between these spectra is the different intensities of the D and G bands. The D bands measured for rGO inside the scratch test trace have slightly lower intensity than the G bands. The same D bands measured for rGO in the area not damaged during the scratch test show larger intensity than G band, similarly to the spectra obtained for the measurements of the tested steels: Ti Grade 2, 316L and WCLV, and also rGO powder (Fig. 5 in the text and Fig. 4 in the Supplementary) before the scratch tests. The obtained values of the I D /I G intensity ratio for individual measurement points are as follows: 1.00 (A and B) and 1.06 (C), so this intensity ratio value is slightly lower for rGO measured in the scratch test area. The I D /I G intensity ratio is used to characterize the amount of defects in graphene materials, and increase when GO is converted into a graphene lattice, more ordered structure [ 60 ]. In the presented WCLV sample, the value of the I D /I G intensity ratio decreases after the scratch test, which may suggest some changes in the structure caused by mechanical action. Therefore, during the scratch test, no destruction and delamination of the rGO layer is observed, but the rGO structure is less ordered. For the further interpretation of scratch test data, mean contact pressure p m was estimated using the classical expression for a spherical indenter under normal load [ 67 ]: $$\:{p}_{m}=\frac{3FN}{2\pi\:{a}^{2}}\:\:,$$ 1 where a is the contact radius, approximated by Hertzian contact mechanics: $$\:a=\sqrt[3]{\frac{3FN}{8}\bullet\:\frac{\frac{1-{v}_{i}^{2}}{{E}_{i}}+\frac{1-{v}_{s}^{2}}{{E}_{s}}}{\frac{1}{{d}_{i}}+\frac{1}{{d}_{s}}}}$$ 2 Calculating an effective modulus for different substrates under the consideration (E s ≈105–220 GPa) and knowing the tip radius R = 100 µm, one can estimate p m within the range of 4.84–7.28 GPa for the FN = 500mN and 7.69–11.55 GPa for the FN = 2000mN respectively. These values exceed typical interfacial adhesion limits for physisorbed graphene, further confirming that the strong bonding observed. Testing the mechanical connection between 3D rGO and substrate In this study, a nickel-chromium alloy was chosen as the substrate for the deposited 3D rGO layer, in contrast to the titanium, stainless steel and tool steel studied previously. To investigate the quality of the 3D rGO-NiCr bond, a set-up was developed to perform mechanical tests of this bond under tensile and compressive loading. A key element of this setup is a novel method to connect and load a free-standing rGO layer with the chosen metal. The studied rGO layer was deposited on the surface of square-shaped wires (0.8 mm side length) made of NiCr alloy, 83 mm apart. The resulting layer connected both the wires and the space between them (Fig. 9 ). The width of the copper electrode used covered both wires. If the distance between the wires was too large, the rGO would not self-connect. The successful deposition of the layer enables the determination of the coating's properties under tensile and compressive loads, as well as the assessment of the quality of the 3D rGO-NiCr bond. To investigate the mechanical deformations of the rGO-NiCr interface, tests were performed using a custom-built testing rig (Supplementary Fig. 6) that enables compression and tension testing of the 3D rGO layer while keeping one NiCr wire stationary and allowing the other to move. This setup allows for measurements of resistance, voltage, temperature, and deformation. Thermal compression and tension testing of the 3D rGO layer The distance between two parallel NiCr wires, one of which is stationary, can be adjusted using a thermal method. The temperature gradient created between the wires causes a change in the position of one of the wires because of its thermal expansion. As a result of temperature changes, the rGO undergoes compression or tension. The lower NiCr wire (Supplementary Fig. 6) is heated using a resistive heating element. It was observed that the resistance of the 3D rGO-NiCr connection changes over a wide range, from fractions of an ohm to several hundred kilohms, as the wires move relative to each other. To measure low resistance values, a four-probe method was used (Supplementary Fig. 7), which minimizes the influence of additional measurement errors related to the resistance of the leads. Measurements were carried out at a humidity of 40% and a temperature of 294 K. Figure 10 a shows the effect of the temperature gradient on changes in the resistance of the connection. Figure 10 a shows the initial state at a temperature of 294 K, characterized by a high resistance that exceeds 1500 W. As the temperature increases, the resistance gradually decreases to a steady-state value of 1350 Ω, followed by a sudden drop. Immediately after the transition to a low resistance state, oscillatory changes in resistance can be observed, which subsequently diminish. When the temperature is heated to the final temperature, the connection resistance reaches approximately 0.5 Ω. During the cooling process, a transition state and oscillations are also observed, with the difference being the presence of temperature hysteresis. Analyzing Fig. 10 a, it should be noted that the initial resistance and the final resistance during the cooling process are similar, despite the presence of hysteresis. This indicates that the rGO-NiCr connections return to their initial state, also in terms of mechanical properties. However, the thermal method has limitations in terms of the maximum achievable deformation. In summary, this stage of the research suggests that it is not so much the temperature change that causes the resistance change of the rGO-NiCr connection, but rather the stretching or compression of the 3D rGO layer. To verify this hypothesis, an additional experiment was conducted, which directly reflects the change in deformation as a function of resistance and simultaneously constitutes a second research method related to the mechanical deformation of the rGO-NiCr connection. Mechanical compression and tension testing of the 3D rGO layer To change the distance between two parallel NiCr wires, a mechanical method can also be employed. Measurements were carried out using a micrometer with an additional worm gear, providing a hundred-fold increase in strain resolution. The limitation of maximum strain, present in the thermal method, is absent in the mechanical method. Tests can be conducted over a wide range of strains until the 3D rGO layer ruptures. Measurements of resistance changes as a function of mechanical strain were made in both directions, that is, during compression and tension. In Fig. 10 b, similar to Fig. 10 a, three regions can be distinguished, each with a different sensitivity s. The average sensitivity s can be expressed as the ratio of the change in resistance ΔR to the change in strain Δε, represented by the formula $$\:s=\frac{\varDelta\:R}{\varDelta\:{\epsilon\:}}\:\:\:\left[\frac{}{\text{%}}\right]$$ 3 . In the first operating range (1) shown in Fig. 10 b, the resistance value increases, and the calculated sensitivity is \(\:{s}_{1}=0.20\:\frac{}{\text{%}}\) . The second range (2), referred to as the high-sensitivity state, indicates a change in the operating state of rGO and covers a strain range of 4–10%, with a sensitivity of \(\:{s}_{2}=7200\:\frac{}{\text{%}}\) . In this range, the resistance value increases sharply, which can be explained by changes in the number of connections between rGO and NiCr. The third range (3) corresponds to a low-resistance state and is relatively narrow, with a low sensitivity of approximately \(\:{s}_{3}=0.15\:\frac{}{\text{%}},\) similar to the first range. The above division into ranges can also be explained by analyzing the structure of rGO during compression and tension. The rGO used in this solution can be treated as a network of resistors, which changes depending on the contact surface between the rGO and NiCr. With significant compression of the wires (Fig. 11 a), the contact surface between 3D rGO and the metal can be considered uniform, which means that there are no empty spaces between graphene and the wire. The tighter the connection, the more R e 1 connections there will be, and the lower the value of the resultant resistance will be. As can be seen from the presented model, this will be a parallel connection of R g and R e 1 , resistances, which can be described by the formula \(\:{R}_{Z}={R}_{e1}{R}_{g1}/\left({R}_{e1}{+R}_{g1}\right)\) . Taking into account that the resistance value of rGO is small [ 68 ], the resistance values observed are mainly caused by the change in the structure of the 3D rGO - NiCr connection. Figure 11 b shows the situation representing the range (2) from Fig. 10 b. As the strain (stretching) increases, the resistance value increases because the number of 3D rGO - NiCr connections begins to decrease - microcracks appear in the structure of the connection. The structure of the resistor connections changes to a 3-layer one, because we can distinguish the outer R e 2 and inner rGO R g 2 layers. It should be noted that the resistance R g 2 of the rGO itself may change lightly; therefore, the change in resistance is due to the number of 3D rGO - NiCr connections. The fewer these connections, the higher the value of the resultant resistance will be. Such a structure can be described by the equation \(\:{R}_{Z}={R}_{e21}+{R}_{e22}+{R}_{g2}\) . The mechanical properties of rGO cause that at a certain strain, further breaking of the 3D rGO - NiCr connection covers other areas (Fig. 11 c), which corresponds to the high resistance state (range (3) from Fig. 10 b). The resistance in this range is expressed by the formula \(\:{R}_{Z}={R}_{e31}+{R}_{e32}+{R}_{g3}\) . The relationship between the resistance values R g for individual ranges is presented as \(\:{R}_{g1}<{R}_{g2}<{R}_{g3}\) , while these changes are small. The relationship between the resistance values Re for individual ranges R e 1 ≪ R e 2 ≪ R e 3 , and these changes are visible in state 3 of high resistance. The above analysis of the resistance behavior of the 3D rGO - NiCr connection explains both the changes visible in the microscopic images (Fig. 11 ) and the changes in resistance values observed during tests carried out by the thermal and mechanical methods (Fig. 10 ). Taking into account the construction of the test stand and the properties of rGO, it can be concluded that the 3D rGO - NiCr connection is broken mainly at the contact with the metal. It was also noted in [ 69 ] that graphene has a small negative temperature coefficient of about 1.5 ⋅10 −3 o C − 1 . Comparing the above values with the results obtained by the authors, it is concluded that the influence of temperature is negligible in relation to the measured resistance changes related to the rGO strain. The oscillations observed by the authors shown in Fig. 10 a can be explained as a quantum interference phenomenon that occurs between individual layers of graphene [ 70 ] that becomes apparent and visible during the compression process at small resistance values after the occurrence of the cooling transient state and before the occurrence of the heating transient state. Potential application of 3D rGO coating on cemented carbide tool inserts for turning process Turning trials were conducted using turning inserts (WNMG080408-LP) coated with the developed 3D rGO layer (current pulse durations t d = 200µs, and constant pulse period t p = 1000 µs). These were compared against commercially available titanium aluminum nitride (TiAlN) PVD coatings of the MC6025 type. The selected inserts feature a specific geometry optimized for steel turning applications, and their LP chip breaker geometry is specifically designed for light to medium turning operations, facilitating effective chip control and reducing cutting forces. The primary objective of these studies was to assess the performance and durability of the tools under controlled machining conditions using C45 steel. The study aimed to determine the influence of the coating type on tool life and machining efficiency, which are critical factors for optimizing machining processes and reducing production costs. The workpiece material chosen for the study was commercial C45 steel, designated according to PN-EN 10083-2. C45 steel is an unalloyed quality steel suitable for heat treatment, characterized by a medium carbon content. In its softened state, C45 steel exhibits a hardness of approximately 220 HB, while after heat treatment, its hardness can range from 55 to 60 HRC. Cylindrical bars with an initial length of 100 mm and a diameter of 30 mm were used for the experimental turning operations. The objective of the machining process was to reduce the diameter of these bars to 10 mm, allowing for observation of tool wear under controlled and consistent conditions. All turning experiments were performed on a DMG MORI CLX350V4 Computer Numerical Control (CNC) lathe. This machine tool is characterized by high precision and dynamic machining capabilities. The lathe is equipped with a main spindle capable of achieving a maximum rotational speed of 5000 rpm and a spindle drive power of 16.5 kW. The inherent stability and rigidity of this machine ensure consistent machining conditions, which are crucial for obtaining reliable and repeatable results in tool wear studies. The turning process was carried out using the following controlled parameters: cutting speed V c = 100 m/min, feed rate f = 0.15 mm/rev, depth of cut a = 1.5 mm. With a depth of cut of 1.5 mm per side, the total radial reduction was 10 mm (from a 15 mm radius to a 5 mm radius). This required 7 cutting passes. Consequently, the total cutting path traversed by the tool during the entire machining operation for one sample was 700 mm. The initial phase of our investigation focused on characterizing the delamination behavior of the PVD coating. We observed that the PVD coating was removed after just the first cutting pass (Fig. 11 a), while the 3D rGO coating remained intact. Visual observations, supplemented by microscopic analyses, were used to identify the exact point at which either the graphene or PVD coatings showed signs of damage or complete delamination. The tool wear criterion was established as reaching a flank wear value of 0.3 mm, significant deterioration of the machined surface quality, an increase in cutting forces, the onset of vibrations, or catastrophic tool failure. Regular measurements of tool wear and a comprehensive analysis of the machined surface quality allowed for continuous monitoring of wear progression. The data collected from this test enabled a direct comparison of tool life for both coating types, facilitating an assessment of the graphene coating's effectiveness in extending tool life under prolonged machining conditions. The established wear limit for the PVD-coated insert occurred after 14 cutting passes (Fig. 11 b). In contrast, the 3D rGO-coated insert wore out after 21 cutting passes. These results demonstrated that inserts incorporating the graphene coating exhibited increased wear resistance, leading to extended tool life and potentially reduced production costs. Considering their unique properties, such as high hardness, low friction coefficient, and chemical inertness, graphene coatings possess transformative potential to revolutionize machining technology. Their integration is expected to lead to significant performance improvements, a considerable reduction in tool wear, and an overall increase in the quality of machined surfaces, thereby pushing the boundaries of conventional manufacturing. Conclusions A novel method for depositing 3D rGO onto metals has been developed, utilizing low-temperature atmospheric plasma combined with electropulse treatment. This method is fully scalable, has been applied to various metal alloys, and can be conducted under ambient conditions. The 3D rGO layer demonstrated strong adhesion to the substrate, as evidenced by TEM images, and exhibited a dense, pore-free structure with most rGO flakes oriented perpendicular to the surface. XPS analysis revealed that after plasma treatment, the carbon content on the Ti surface decreased significantly, while the oxygen content doubled. This indicates the formation of a thicker TiO 2 layer and increased surface oxygenation, enhancing the adhesion of the graphene-like coating. The C 1s spectra of both the pristine rGO flakes and the deposited 3D rGO layer exhibited striking similarities, suggesting a graphene-like structure for the coating and explaining its high hardness. Nanoindentation tests demonstrated a significant enhancement in the mechanical properties of the titanium substrate due to the 3D rGO coating. The average hardness and indentation modulus of the coated surface were higher than those of the uncoated substrate, indicating the contribution of the graphene layer to the increased stiffness and resistance to deformation. Notably, certain regions within the coating exhibited exceptionally high hardness and modulus values, aligning with those reported for high-quality graphene. The adhesion of 3D rGO coatings to various metal substrates was evaluated by scratch testing, which revealed strong adhesion without visible delamination. Sequential scratch testing on titanium samples demonstrated the excellent wear resistance and adhesion of the coating under repeated mechanical loading. To further understand the rGO-metal bond, tensile and compressive tests were conducted on the 3D rGO layer. The results confirmed a strong adhesion between the layer and the substrate, with the 3D rGO layer exhibiting a maximum strain of up to 30% before failure, without complete detachment from the metal. This suggests potential applications in various electronic sensors due to the layer's high sensitivity. The durable 3D rGO coatings produced using this scalable method offer numerous practical applications that leverage graphene's unique properties, particularly its exceptional mechanical strength. Potential applications include coatings for tools used in various manufacturing processes. It was experimentally demonstrated during the turning process that the tool wear of the 3D rGO-coated insert increased by 150% compared to the PVD-coated insert, which we consider a significant success. During the turning process, under sustained cyclic loading and high temperatures, the applied layer remains undamaged throughout the tool's full working cycle. The strong bond between graphene and metal has significant implications for engineering applications where graphene is first time used as a robust bulk layer rather than a previously used component of composite materials or porous structures. Methods Materials Few-layer graphene oxide was obtained from Nanomaterials (Poland), prepared by a modified Hummers method using commercially available natural graphite with 99.0% purity (Acros Organics, USA, 325 mesh). Reduced graphene oxide exhibited a stacked nanostructure with an average lateral dimension of approximately 8 nm and a height of approximately 1 nm, with an interlayer spacing of 0.4 nm between 2–3 graphene layers [ 71 ]. This study used sheet samples of Grade 2 Commercial Pure Titanium (ASTM B 265) with a thickness of 2 mm (HWN titan GmbH, Germany), tool steel (1.2344) WCLV with a thickness of 3.6 mm, austenitic stainless steel AISI 304 with a thickness of 0.5 mm, and Ni90Cr10 (Chromel) wire with a diameter of 0.8 mm. Characterization The preparation of the sample for microstructural analysis was performed using a dual beam FIB-SEM/XE-PFIB FEI HELIOS G4 PFIB CXE. Observations were carried out using a Hitachi H800 transmission electron microscope equipped with a Qumesa CCD camera, a Keyence VHX-6000 optical microscope and a Sigma 500VP scanning electron microscope. X-ray photoelectron spectroscopy (XPS) measurements were performed using a SPECS PHOIBOS 100 spectrometer. Both the Mg (1253.6 eV) and Al (1486.6 eV) anodes, operating at 250 W, were used for high-resolution spectra acquisition. The obtained spectra were fitted with Gaussian-Lorentzian curve profiles after subtracting a Shirley background using CasaXPS v.2.3.19 software. The reported binding energies have an accuracy of ± 0.1 eV. All binding energies were referenced to the C 1s peak at 284.8 eV. Additionally, the 3D structures of the surface layer were modelled using Quases™ 'Analyze' software [ 72 ]. A 'buried layer' model was employed to interpret the morphology of the analyzed layers. This class of 3D profiles can be used to model a wide variety of solids, including substrates with an overlayer, an overlayer on a substrate, a buried layer, and homogeneous solids. Raman spectra were acquired using a Horiba Jovin Yvon HR800 UV spectrometer. All nanoindentation tests were performed using an Anton-Paar UNHT3 ultrananoindenter equipped with a Berkovich indenter tip. To achieve this, standardized adhesion testing methods were employed, specifically scratch testing using the Anton-Paar MCT3 apparatus equipped with a Rockwell diamond indenter with a spherical radius of 100 µm. Electrical measurements were made using the following equipment: resistance – Agilent 34420A, voltages – Agilent 34401A, power supply – Hewlett Packard E3631A, oscilloscope – LeCroy LT224. Temperature measurements were acquired using a Hewlett-Packard 34970A with a type K thermocouple. All turning experiments were performed on a DMG MORI CLX350V4 Computer Numerical Control (CNC) lathe. Declarations Funding Open access funding provided by Wroclaw University of Science and Technology. Author Contribution Z.Z. conceived the idea and supervised the project, fabricated devices and 3D rGO samples, performed a resistance measurement during tensile tests, and wrote the manuscript. W.T. performed XPS analysis. B.B. performed Raman measurements. M.P. carried out the mechanical testing and scratch test. M.R.G. performed the electron microscopy characterization. R.W. carried out the contact angle measurements. K.K. performed the turning process. D.D. performed a resistance measurement during tensile tests. All authors discussed and interpreted the results and contributed to the writing of the manuscript. Data Availability The main datasets generated and analysed during the current study are available in the repository [https://doi.org/10.18150/BMOIZM](https:/doi.org/10.18150/BMOIZM) , RepOD. More data are available from the corresponding author on reasonable request. References Lee, C., Wei, X., Kysar, J. W. & Hone, J. Measurement of the elastic properties and intrinsic strength of monolayer graphene. Science 321 , 385–388 (2008). Geim, A. K. Graphene: status and prospects. Science 324 , 1530–1534 (2009). Zhu, Y. et al. Graphene and graphene oxide: synthesis, properties, and applications. Adv. Mater. 22 , 3906–3924 (2010). Ramezani, M. J. & Rahmani, O. A review of recent progress in the graphene syntheses and its applications. Mech. Adv. Mater. Struct. , 1–33 (2024). Strupiński, W. et al. Baranowski. Graphene epitaxy by Chemical Vapor Deposition on SiC. Nano Lett. 11 , 1786–1791 (2011). Yan, Z. et al. Toward the synthesis of wafer-scale single-crystal graphene on copper foils. ACS Nano . 6 , 9110 (2012). Hao, Y. et al. The role of surface oxygen in the growth of large single-crystal graphene on copper. Science 342 , 720–723 (2013). Levy, N. et al. Crommie. Strain-induced pseudo magnetic fields greater than 300 Tesla in graphene nanobubbles. Science 329 , 544 (2010). Chen, W. & Yan, L. Situ Self-Assembly of Mild Chemical Reduction Graphene for Three-Dimensional Architectures. Nanoscale 3 , 3132–3137 (2011). Estevez, L., Kelarakis, A., Gong, Q., Da’as, E. H. & Giannelis, E. P. Multifunctional Graphene/Platinum/Nafion Hybrids via Ice Templating. J. Am. Chem. Soc. 133 , 6122–6125 (2011). Xu, Z. & Gao, C. Graphene Chiral Liquid Crystals and Macroscopic Assembled Fibres. Nat. Commun. 2 , 571 (2011). Lin, Y. M. et al. Ph. 100-GHz transistors from wafer-scale epitaxial graphene. Science 327 , 662 (2010). Chen, K. W., Chen, L. B., Chen, Y. Q., Bai, H. & Li, L. Three-Dimensional Porous Graphene-Based Composite Materials: Electrochemical Synthesis and Application. J. Mater. Chem. 22 , 20968–20976 (2012). El-Kady, M. F., Strong, V., Dubin, S. & Kaner, R. B. Laser Scribing of High-Performance and Flexible Graphene-Based Electrochemical Capacitors. Science 335 , 1326–1330 (2012). Jakus, A. E. et al. Three-Dimensional Printing of High-Content Graphene Scaffolds for Electronic and Biomedical Applications. ACS Nano . 9 , 4636–4648 (2015). Zhang, Y. et al. Broadband and Tunable High-Performance Microwave Absorption of an Ultralight and Highly Compressible Graphene Foam. Adv. Mater. 27 , 2049–2053 (2015). Zhao, J. P., Ren, W. C. & Cheng, H. M. Graphene Sponge for Efficient and Repeatable Adsorption and Desorption of Water Contaminations. J. Mater. Chem. 22 , 20197–20202 (2012). Kou, L. et al. Wet-Spun, Porous, Orientational Graphene Hydrogel Films for High-Performance Supercapacitor Electrodes. Nanoscale 7 , 4080–4087 (2015). Zhao, X., Yao, W., Gao, W., Chen, H. & Gao Wet-Spun, C. Superelastic Graphene Aerogel Millispheres with Group Effect. Adv. Mater. 29 , 1701482 (2017). Luan, V. H. et al. Synthesis of a Highly Conductive and Large Surface Area Graphene Oxide Hydrogel and Its Use in a Supercapacitor. J. Mater. Chem. (2013). 1 A 208 – 211. Peng, Z., Lin, J., Ye, R., Samuel, E. L. & Tour, J. M. Flexible and Stackable Laser-Induced Graphene Supercapacitors. ACS Appl. Mater. Interfaces . 7 , 3414–3419 (2015). Senyuk, B. et al. Three-dimensional patterning of solid microstructures through laser reduction of colloidal graphene oxide in liquid-crystalline dispersions. Nat. Commun. 6 , 7157. 10.1038/ncomms8157 (2015). Fu, K. et al. Graphene Oxide-Based Electrode Inks for 3D-Printed Lithium-Ion Batteries. Adv. Mater. 28 , 2587–2594 (2016). Fu, K. et al. Graphene Oxide-Based Electrode Inks for 3D-Printed Lithium-Ion Batteries. Adv. Mater. 28 , 2587–2594 (2016). Zhao, Z., Lin, C. Y., Tang, J. & Xia, Z. Catalytic Mechanism and Design Principles for Heteroatom-Doped Graphene Catalysts in Dye-Sensitized Solar Cells. Nano Energy . 49 , 193–199 (2018). Wang, R., Lu, K. Q., Zhang, F., Tang, Z. R. & Xu, Y. J. 3D Carbon Quantum Dots/Graphene Aerogel as a Metal-Free Catalyst for Enhanced Photosensitization Efficiency. Appl. Catal. 233B, 11 – 18 (2018). Ramadoss, A. et al. Fully Flexible, Lightweight Performance All-Solid- State Supercapacitor Based on 3-Dimensional-Graphene/Graphite-Paper. J. Power Sources . 337 , 159–165 (2017). Politou, M. et al. Transition Metal Contacts to Graphene. Appl. Phys. Lett. 107 , 153104 (2015). He, Q., Wu, S., Yin, Z. & Zhang, H. Graphene-Based Electron. Sens. Chem. Sci. 3 , 1764–1772 (2012). Ataca, C., Aktürk, E., Ciraci, S. & Ustunel, H. High-Capacity Hydrogen Storage by Metallized Graphene. Appl. Phys. Lett. 93 , 043123 (2008). Park, H. & Park, J. M. Electrophoretic deposition of graphene oxide on mild carbon steel for anti-corrosion application. Surf. Coat. Technol. 254 , 167–174 (2014). Berman, D., Erdemir, A. & Sumant, A. V. Few layer graphene to reduce wear and friction on sliding steel surfaces. Carbon 54 (0), 454e459 (2013). Snook, I. & Barnard, A. Theory, experiment and applications of graphene nano-flakes. J. Nanosci. Lett. 1 , 50–60 (2011). Khomyakov, P. A. et al. First-Principles Study of the Interaction and Charge Transfer Between Graphene and Metals. Phys. Rev. B: Condens. Matter Mater. Phys. 79 , 195425 (2009). Wang, Q., Pang, R. & Shi, X. Molecular Precursor Induced Surface Reconstruction at Graphene/Pt(111) Interfaces. J. Phys. Chem. 119C, 22534 – 22541 (2015). Biswas, R. K., McGlynn, P., O'Connor, G. M. & Scully, P. and and Plasma enhanced planar crystal growth of laser induced graphene. Mater. Lett. 343 (2023). Conrad, H. Electroplasticity in metals and ceramics. Mater. Sci. Eng. 287 A 276–287 (2000). Xie, H. et al. J. Mater. Sci. Eng. 637A , 23–28 (2015). Qin, R. S. & Su, S. X. Thermodynamics of crack healing under electropulsing. J. Mater. Res. 17 , 2048–2052 (2002). Rahnama, A. & Qin, R. S. Electropulse-induced microstructural evolution in a 0.14% ferritic-pearlitic steel. Scripta Mater. 96 , 17–20 (2015). Li, D., Yu, E. & Liu, Z. Microscopic mechanism and numerical calculation of electroplastic effect on metal's flow stress. Mater. Sci. Eng. 580A , 410–413 (2013). Geim, A. K. & Novoselov, K. S. Nat. Mater. 6 , 183 (2007). Zimniak, Z. Influence of high density electric currents pulses on plastic deformation. Steel Res. Int. 81 , 729–732 (2010). Pearson, W. B. Tabulated Lattice Spacings and Data of Borides, Carbides, Hydrides, Nitrides, and Binary Oxides. In A Handbook of Lattice Spacings and Structures of Metals and Alloys; Elsevier: Amsterdam, The Netherlands, 218–246, (1958). QUASES-IMFP-TPP2M Ver. 3.0 Inelastic electron mean free paths calculated from the TPP-2M formula; Vincent Crist, B. Handbooks of Monochromatic XPS Spectra, v.1, The Elements and Native Oxides, XPS International, LLC, Grinter, D. C. et al. Adsorption and activation of CO2 on Pt/CeOx/TiO2(110): Role of the Pt-CeOx interface. Surf. Sci. 710 , 121852. https://doi.org/10.1016/j.susc.2021.121852 (2021). QUASES-Tougaard. Software for Quantitative XPS/AES of Surface Nano-structures. Wagner, C. D. et al. Standard Reference Database 20, Version 3.4 (web version) (2003). http:/srdata.nist.gov/xps/) Biesinger, M. C., Lau, L. W. M., Gerson, A. & Smart, R. S. C. Resolving Surface Chemical States in XPS Analysis of First Row Transition Metals, Oxides and Hydroxides: Sc, Ti, V, Cu and Zn. Appl. Surf. Sci. 257 , 887–898 (2010). Biesinger, M. C. Accessing the robustness of adventitious carbon for charge referencing (correction) purposes in XPS analysis: Insights from a multi-user facility data review. Appl. Surf. Sci. 597 , 153681. https://doi.org/10.1016/j.apsusc.2022.153681 (2022). Pimenta, M. A., Dresselhaus, G., Dresselhaus, M. S., Cancado, L. G. & Jorioa, Saito, A. R. Studying disorder in graphite-based systems by Raman spectroscopy. Phys. Chem. Chem. Phys. 9 , 1276–1291 (2007). Stankovich, S. et al. Synthesis of graphene-based nanosheets via chemical reduction of exfoliated graphite oxide. Carbon 45 , 1558–1565 (2007). Ferrari, A. C. Raman spectroscopy of graphene and graphite: Disorder, electron–phonon coupling, doping and nonadiabatic effects. Solid State Commun. 143 , 47–57 (2007). Khan, Q. A., Shaur, A., Khan, T. A., Joya, Y. F. & Awan, M. S. Characterization of reduced graphene oxide produced through a modified Hoffman method. Cogent Chem. 3 , 1298980 (2017). Malard, L. M., Pimenta, M. A., Dresselhaus, G. & Dresselhaus, M. S. Raman spectroscopy in Graphene. Phys. Rep. 473 , 51–87 (2009). Dovbeshko, G. et al. Raman modes and mapping of graphene nanoparticles on Si and photonic crystal substrates. Opt. Materials: X . 15 , 100163. https://doi.org/10.1016/j.omx.2022.100163 (2022). Park, J. H. & Park, J. M. Electrophoretic deposition of graphene oxide on mild carbon steel for anti-corrosion application. Surf. Coat. Technol. 254 , 167–174 (2014). Zhang, Y., Hao, H. & Wang, L. Effect of morphology and defect density on electron transfer ofelectrochemically reduced graphene oxide. Appl. Surf. Sci. 390 , 385–392. http://dx.doi.org/10.1016/j.apsusc.2016.08.127 (2016). Hafiza, S. M. et al. A practical carbon dioxide gas sensor using room-temperaturehydrogen plasma reduced graphene oxide. Sens. Actuators . 193B , 692–700 (2014). Fischer-Cripps, A. C. & Nanoindentation Springer. https://www.springer.com/gp/book/9780387220451 Oliver, W. C. & Pharr, G. M. An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments. J. Mater. Res. 7 (6), 1564–1583 (1992). Bobko, C. & Ulm, F. J. The nano-mechanical morphology of shale. Mech. Mater. 40 (4), 318–337 (2008). Constantinides, G., Ulm, F. J. & Vliet, K. V. On the use of nanoindentation for cementitious materials. Mater. Struct. 36 (3), 191–196 (2003). Huo, Z. et al. Nanoindentation of circular multilayer graphene allotropes. Sci. China Technol. Sci. 62 , 269–275 (2019). Lee, C., Wei, X., Kysar, J. W. & Hone, J. Measurement of the Elastic Properties and Intrinsic Strength of Monolayer Graphene.. Science . 321 (5887), 385–388 (2008). Budynas, R. G. & Nisbett, J. K. Shigley's mechanical engineering design () Vol. 9pp. 409–473 (McGraw-Hill, 2011). Zhang, B. X., Hou, Z. L., Yan, W., Zhao, Q. L. & Zhan, K. T. Multi-dimensional flexible reduced graphene oxide/polymer sponges for multiple forms of strain sensors. Carbon 25 , 199–206 (2017). Sibilia, S. et al. G. and Temperature-dependent Electr. resistivity macroscopic graphene nanoplatelet strips Nanatechnol. 32 , 275701 (2021). Benameur, M. et al. Electromechanical oscillations in bilayer graphene. Nat. Commun. 6 , 8582 (2015). Stobinski, L. et al. J. Electron Spectrosc. Relat. Phenom. 195 , 145–154 (2014). Tougaard, S. & QUASES™ Version 4.4, Software for Quantitative XPS/AES of Surface Nano – structures by Analysis of the Peak Shape, Background (2000). Additional Declarations No competing interests reported. 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1","display":"","copyAsset":false,"role":"figure","size":261268,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSteps involved in creating an rGO coating on a metal sheet.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e Low-temperature argon plasma surface treatment. \u003cstrong\u003eb\u003c/strong\u003e Coating the surface with rGO flakes. \u003cstrong\u003ec \u003c/strong\u003eElectropulse treatment involving the application of a copper electrode with appropriate force to the graphene layer while simultaneously supplying pulsed current from a power supply. \u003cstrong\u003ed\u003c/strong\u003e The resulting 3D rGO layer.\u003c/p\u003e","description":"","filename":"image1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7741311/v1/61809269d077fe688c5f7125.jpg"},{"id":94590891,"identity":"d7dc2805-cab5-4155-ba22-03db72e899c4","added_by":"auto","created_at":"2025-10-28 18:21:37","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":403388,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMicrostructure of rGO flakes and a 3D rGO layer.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003eGraphene flakes (TEM). \u003cstrong\u003eb\u003c/strong\u003e View of a sample with a deposited 3D rGO layer (SEM). \u003cstrong\u003ec \u003c/strong\u003eCross section of the graphene coating; visible connection of the coating to the substrate. \u003cstrong\u003ed \u003c/strong\u003eCross section of the graphene coating, visible oval, spheroidal morphology of the coating grains (TEM). \u003cstrong\u003ee\u003c/strong\u003e Microstructure of the coating in a longitudinal section - visible dominance of the orientation of flakes facing the observed surface. \u003cstrong\u003ef \u003c/strong\u003eMicrostructure of the coating in a longitudinal section, visible orientation of the flakes, revealing individual graphene flake packages (TEM).\u003c/p\u003e","description":"","filename":"image2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7741311/v1/e13b50dbfab9fc2f3583780a.jpeg"},{"id":94591799,"identity":"c1626a6c-f77a-4d37-9320-60974440efdf","added_by":"auto","created_at":"2025-10-28 18:22:40","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":168819,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eXPS C 1s, Ti 2p core level spectra and modelled 3D structure for oxides layer on Ti sample.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e As received. \u003cstrong\u003eb\u003c/strong\u003e After degreasing and mechanical grinding. \u003cstrong\u003ec\u003c/strong\u003e After plasma irradiation (left panel), and QUASES™ ‘Analyze’ modelled peaks of the Ti surface, modified with a plasma beam: \u003cstrong\u003ed\u003c/strong\u003e Ti 2p, \u003cstrong\u003ee\u003c/strong\u003e C KLL, \u003cstrong\u003ef\u003c/strong\u003e O KLL using the Mg Kα source, and the Ti 2p core level spectra for titanium sample surface: \u003cstrong\u003eg\u003c/strong\u003e After degreasing and mechanical grinding, \u003cstrong\u003eh\u003c/strong\u003e After plasma irradiation (right panel).\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-7741311/v1/45741122a9cff383f5a2c57c.png"},{"id":94591800,"identity":"e79c314b-7fbf-4c13-9f13-a8967ba8572a","added_by":"auto","created_at":"2025-10-28 18:22:40","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":62522,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eXPS C 1s core level spectra.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e Commercial graphene, \u003cstrong\u003eb\u003c/strong\u003e rGO and \u003cstrong\u003ec\u003c/strong\u003e Ti covered 3D rGO.\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-7741311/v1/c1e59d443114e16ada0f0b49.png"},{"id":94591272,"identity":"53d8ba10-a228-46ef-8643-a4fb66423781","added_by":"auto","created_at":"2025-10-28 18:22:04","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":88329,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRaman spectra.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003erGO and 3D rGO layer on Ti Grade 2.\u003c/p\u003e","description":"","filename":"image5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7741311/v1/9b3b7a8e8c97c49effff8eea.jpeg"},{"id":94591038,"identity":"84b4d5ff-930e-4ec1-8c3b-5a8462f47443","added_by":"auto","created_at":"2025-10-28 18:21:45","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":1386396,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTargeted nanoindentation analysis of the 3D rGO coating on WCLV substrate.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e Optical micrograph showing the selected region of the 3D reduced graphene oxide (rGO) coating subjected to indentation testing. \u003cstrong\u003eb\u003c/strong\u003e Spatial map of indentation modulus E\u003csub\u003eIT\u003c/sub\u003e, revealing heterogeneity in stiffness distribution across the coating, with localized regions exceeding 500 GPa. \u003cstrong\u003ec\u003c/strong\u003e Spatial map of indentation hardness H\u003csub\u003eIT\u003c/sub\u003e, with peak values above 35 GPa indicating highly reinforced domains. \u003cstrong\u003ed\u003c/strong\u003e Scatter plot of indentation modulus versus hardness for all indentation points, demonstrating a strong correlation and wide variability in mechanical response. Insets: probability density histograms of E\u003csub\u003eIT\u003c/sub\u003e and H\u003csub\u003eIT\u003c/sub\u003e, highlighting the multimodal character of the data. All measurements were performed using depth-controlled nanoindentation (maximum depth: 200 nm; spacing: 10 µm) to ensure statistical independence and to isolate the mechanical response of the 3D rGO layer.\u003c/p\u003e","description":"","filename":"image6.png","url":"https://assets-eu.researchsquare.com/files/rs-7741311/v1/f3c304274ac19b217c805c2f.png"},{"id":94591042,"identity":"395b4815-b69e-48bf-969b-4c98f3246a81","added_by":"auto","created_at":"2025-10-28 18:21:45","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":3099107,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eScratch test results for 3D rGO surfaces on three different substrates\u003c/strong\u003e.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003ea\u003c/strong\u003e Titanium, \u003cstrong\u003eb\u003c/strong\u003e Stainless Steel, and \u003cstrong\u003ec\u003c/strong\u003e WCLV steel. The scratch direction is indicated with arrows, beginning from the 3D rGO -coated region and transitioning to the substrate. All tests were performed with a constant normal force of \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eN\u003c/em\u003e\u003c/sub\u003e\u0026nbsp;=\u0026nbsp;2000\u0026nbsp;mN over a scratch length of 1 mm. No significant detachment of 3D rGO was observed, indicating strong adhesion across all samples. However, minimal 3D rGO migration is visible on the stainless steel substrate, which may suggest slightly weaker adhesion compared to the titanium and WCLV substrates.\u003cbr\u003e\n\u003cstrong\u003ed \u003c/strong\u003eSequential scratch test on the 3D rGO coated titanium substrate. The direction of the scratch test transitions from the titanium surface to the graphene coating, with \u003cem\u003eX\u003c/em\u003e\u0026nbsp;=\u0026nbsp;0.34\u0026nbsp;mm marking the boundary between the two regions. The test involved 18 consecutive passes over a scratch length of 700\u0026nbsp;µm, under a constant normal force of \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eN\u003c/em\u003e\u003c/sub\u003e\u0026nbsp;=\u0026nbsp;500\u0026nbsp;mN. \u003cstrong\u003ee \u003c/strong\u003eGraph showing the penetration depth (black, left axis) and the frictional force (orange, right axis) as a function of distance along the scratch path. The transition from titanium to graphene is evident by the increase in both the penetration depth and the frictional force at \u003cem\u003eX\u003c/em\u003e\u0026nbsp;=\u0026nbsp;0.34\u0026nbsp;mm, which highlights the mechanical response of the graphene coating during sequential scratch tests.\u003c/p\u003e","description":"","filename":"image7.png","url":"https://assets-eu.researchsquare.com/files/rs-7741311/v1/5fd316aeecc5301b9bd4f02c.png"},{"id":94590991,"identity":"9a84e761-5988-4ee5-989c-16de6a1398f1","added_by":"auto","created_at":"2025-10-28 18:21:42","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":378966,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePicture and Raman spectra of the WCLV sample after the scratch test.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"image8.png","url":"https://assets-eu.researchsquare.com/files/rs-7741311/v1/d9e4586e083c158cd5caedf8.png"},{"id":94591276,"identity":"180a74cc-3b8f-4ca7-94e0-7d0200598497","added_by":"auto","created_at":"2025-10-28 18:22:05","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":212652,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSteps of 3D rGO layer production on NiCr wires.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e Low-temperature argon plasma treatment of the wires, \u003cstrong\u003eb\u003c/strong\u003e Coating the wire surface with rGO flakes, \u003cstrong\u003ec \u003c/strong\u003eElectroplastic treatment involving the application of a copper electrode with appropriate force to the graphene layer on the wires, while simultaneously supplying pulsed current from a power supply, \u003cstrong\u003ed\u003c/strong\u003e Tensile and compressive testing of the deposited layer.\u003c/p\u003e","description":"","filename":"image9.png","url":"https://assets-eu.researchsquare.com/files/rs-7741311/v1/13b77cd0470d00689fd9739b.png"},{"id":94591298,"identity":"9dc10a80-12ab-4817-bd54-8e68d1608ab5","added_by":"auto","created_at":"2025-10-28 18:22:06","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":69848,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eResults of rGO-NiCr junction studies.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStates of high resistance (1), transition state (2), and low resistance (3).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e Changes in resistance as a function of temperature. The initial state is a state of high resistance (1). During heating, a slow change in resistance occurs until a steady state is reached, followed by a sudden drop (2) in this value, which is shown in a magnified view of the highlighted area. During the cooling process, high sensitivity is also observed, along with hysteresis. \u003cstrong\u003eb\u003c/strong\u003e Changes in resistance as a function of strain. In the first range (1), the resistance value is high and characterized by a low sensitivity. The second range (2), referred to as the high sensitivity state, indicates a change in the operating state of rGO. The third range includes the low resistance state (3), while the sensitivity is similar to the first range (1).\u003c/p\u003e","description":"","filename":"image10.png","url":"https://assets-eu.researchsquare.com/files/rs-7741311/v1/a884419114cfa93f8459a5fc.png"},{"id":94590942,"identity":"1609859e-b6f0-44ff-939c-d26ef51d42ef","added_by":"auto","created_at":"2025-10-28 18:21:41","extension":"jpeg","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":400056,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSchematic illustration of 3D\u0026nbsp;rGO–NiCr connection structure and its equivalent circuit diagram.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e Microscopic images of the 3D rGO-NiCr interface in a low-resistance state. \u003cstrong\u003eb\u003c/strong\u003e Transitional state, and \u003cstrong\u003ec\u003c/strong\u003e High-resistance state. \u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003ee\u003c/em\u003e\u003c/sub\u003e represents the resistance of the 3D rGO-NiCr interface, and \u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003eg\u003c/em\u003e\u003c/sub\u003e represents the resistance of the 3D rGO layers. The right-hand side panels show magnified views with more clearly visible voids that correspond to the breakage of the 3D rGO-NiCr interface.\u003c/p\u003e","description":"","filename":"image11.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7741311/v1/74acad6c6e7342a538889471.jpeg"},{"id":94590994,"identity":"f4c8a33e-14d8-4676-9dd3-18dcee052bea","added_by":"auto","created_at":"2025-10-28 18:21:43","extension":"jpeg","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":448781,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFig. 11. Photos of turning inserts.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e image of the tool without the 3D rGO coating after 1 cutting pass, showing visible PVD layer loss, \u003cstrong\u003eb\u003c/strong\u003e tool flank face with edge chipping after 14 cutting passes, \u003cstrong\u003ec\u003c/strong\u003e tool flank face with the applied 3D rGO layer, \u003cstrong\u003ed\u003c/strong\u003e tool rake surface showing the visible 3D rGO layer, \u003cstrong\u003ee\u003c/strong\u003e magnified view of the 3D rGO layer against the carbide cemented surface.\u003c/p\u003e","description":"","filename":"image12.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7741311/v1/54434d1accb4dc4f3d3241a0.jpeg"},{"id":101690697,"identity":"bce42cb9-ece3-4636-a668-07cab4210d3c","added_by":"auto","created_at":"2026-02-02 16:07:45","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":8704350,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7741311/v1/eb417b02-a0c8-4b76-9756-f7d2ba7f618e.pdf"},{"id":94591802,"identity":"746ff1be-56fd-4ff9-981e-ba09096fb950","added_by":"auto","created_at":"2025-10-28 18:22:41","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":17214512,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-7741311/v1/7339391dcdb3e688ec83f38d.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Three-dimensional bulk reduced graphene oxide coatings with strong metal adhesion via cold plasma and pulsed current","fulltext":[{"header":"Introduction","content":"\u003cp\u003eGraphene, is a single-atomic-layer material composed of carbon atoms packed in a honeycomb structure of sp\u003csup\u003e2\u003c/sup\u003e hybridized, has been intensively studied because of its extremely physical and mechanical properties with the highest-known intrinsic strength of 130 GPa and a Young\u0026rsquo;s modulus of 1 TPa [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Its outstanding high strength and elasticity modulus, remarkable electron mobility (15,000 cm\u003csup\u003e2\u003c/sup\u003e V\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e S\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), super high thermal conductivity (5,000 W\u0026middot;m\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u0026middot;K\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), high optical transparency and a non-doped sheet resistance of ~\u0026thinsp;350 Ohm per square [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eGraphene can be deposited on metals using various techniques, the most common being [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]: layer-by-layer (LbL), spin coating, spray coating, dip coating, electrophoretic deposition (EPD), dry spray deposition, cold spray (CS), chemical vapor deposition (CVD), and physical vapor deposition (PVD). CVD, a high-temperature process, is the most prevalent method, typically operating between 650\u0026deg;C and 1000\u0026deg;C. Deposition often occurs on Cu, Ni, or SiC substrates [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. To reduce the growth temperature of large-area graphene using thermal CVD [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], a variant with an increased plasma content, known as PECVD, has been proposed [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. This method leverages the ability of the plasma to sustain multiple reactive species simultaneously, providing a rich chemical environment. This is the primary advantage of using plasma in such processes, as it facilitates the removal of native oxide and the smoothing of the surface of copper, thus increasing the growth rate of graphene on copper substrates and allowing lower deposition temperatures (\u0026lt;\u0026thinsp;420\u0026deg;C). The CVD technique has certain limitations, including the need for a high-vacuum system, making it relatively expensive. Additionally, thermally induced strain and topological defects can lead to giant pseudo-magnetic fields and charging effects [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], consequently diminishing electrical properties. PVD shares similar limitations and further requires plasma technologies. EPD, on the other hand, is user-friendly, cost-effective, and suitable for large, complex surfaces.\u003c/p\u003e\u003cp\u003eThe methods discussed above typically allow for the creation of single-atom-thick layers on metal surfaces. While such layers exhibit the excellent properties that graphene offers, they present a barrier to practical applications. A solution to this problem is the creation of a three-dimensional graphene-based structure that inherits the best properties of graphene, known as a 3D graphene material. It is important to note that the graphene walls in a 3D graphene material should consist of less than 10 graphene layers. 3D graphene is a crucial material in various engineering applications. However, the production of macroscopic 3D graphene materials remains a challenge in modern nanotechnology. Currently known methods for obtaining a three-dimensional graphene macrostructure include: mild chemical reduction [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], ice templating [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], wet-spinning [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], tape casting [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], electrochemical construction [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], laser scribing [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] and printing technology [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. These methods can produce various 3D shapes such as graphene foam [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], graphene sponge [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], fibers [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], millispheres [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], and others.\u003c/p\u003e\u003cp\u003eMany 3D graphene structures are produced directly from GO through a self-assembly method called GO-derived 3D graphene materials, which are usually referred to as 3D rGO. The development of 3D rGO has had a significant impact on its broader use in various composite materials and practical applications [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Another method of obtaining graphene is laser-induced graphene (LIG). This method is one of the most effective ways to prepare porous 3D graphene and has applications in a wide range of electronic devices [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. An interesting method is also the three-dimensional patterning of solid microstructures through laser reduction of colloidal graphene oxide in liquid-crystalline dispersions [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. In this method, GO flakes and pulsed near-infrared laser were used. Three-dimensional functional solid microstructures of rGO on a glass substrate were obtained. 3D graphene materials hold great promise for numerous practical applications, including batteries [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], supercapacitors [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], solar cells [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e], fuel cells [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e], and flexible electronics [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Regarding the application of graphene coatings produced on metals, there are many applications, including potential use in microelectronic devices [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e], sensors [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e], energy storage [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e], and to protect metallic materials from corrosion [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e], reduce wear and friction [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Therefore, a cheap and simple method is needed to deposit a layer of 3D rGO on metals, characterized by good adhesion to the substrate, which is very important for practical engineering applications.\u003c/p\u003e\u003cp\u003eThis article presents a method for creating a durable bond between rGO and metal alloys at room temperature and atmospheric pressure, resulting in a 3D rGO coating. This two-step method involves the initial preparation of the metal surface using argon cold plasma, followed by a graphene deposition method that leverages graphene's exceptional electrical conductivity. Plasma treatments aim to convert low-energy surfaces to higher-energy surfaces by removing surface hydrogen and introducing oxygen-containing species. In the second step, short, high-current electric pulses are applied to bond the rGO to the metal substrate. This method is cost-effective because it uses graphene flakes, one of the most affordable forms of graphene. Graphene flakes with a few layers are easier to produce in large quantities and offer a greater range of structural configurations due to their corner states, edge states, and diverse shapes [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. The bonding mechanism between graphene and metal can vary. Depending on the metal and configuration, it can be weakly physisorbed or strongly chemisorbed on graphene [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. For instance, Ag, Al, Cu, Cd, Ir, and Au tend to form physisorbed interfaces with graphene, while Co, Ru, Pd, and Ti tend to form chemisorbed interfaces. Some metals, such as Ni and Pt, can participate in both physisorption and chemisorption with graphene [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e].\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n\u003ch2\u003ePreparation\u003c/h2\u003e\n\u003cp\u003eTo achieve a strong rGO-metal bond, the surface must be pretreated. This is crucial because without it the bond would be insufficiently strong. Ratul Kumar et al. [\u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e] first observed that cold plasma aids in the process of depositing graphene using the LIG method on a polyimide (PI) surface. The study used contact angle measurement. The surface energy of PI increases with wettability, reducing the activation energy of graphene nuclei diffusion and improving the crystallinity and conductivity of LIG. In our research, cold plasma was used to pretreat the metal surface. Surfaces dominated by carbon-hydrogen (C-H) bonds tend to have low surface energies and thus are less wettable. Surfaces rich in oxygen-hydrogen bonds have higher surface energies and therefore better adhesion characteristics, which were exploited during pretreatment. To bond rGO to the metal, we employed a pulsed current inducing an electroplastic effect (EPE) [\u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e]. EPE occurs in metals when they are simultaneously subjected to plastic deformation and a pulsed flow of high-density short-duration electric current. A well-known outcome of this effect is a reduction in yield stress and an increase in plastic deformation [\u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e]. The effect is also used to modify the structural phases of a material to enhance fatigue resistance [\u003cspan class=\"CitationRef\"\u003e39\u003c/span\u003e], reduce internal stresses, and alter the microstructure [\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e]. It is generally accepted that the electroplastic effect is due to the force of the electron wind exerted by the electrons on dislocations within a crystal [\u003cspan class=\"CitationRef\"\u003e41\u003c/span\u003e]. In our work, we exploited the high electron velocity in graphene (where charge carriers behave like relativistic particles [\u003cspan class=\"CitationRef\"\u003e42\u003c/span\u003e]) to amplify the electroplastic effect. This results in plastic deformation occurring at lower applied forces [\u003cspan class=\"CitationRef\"\u003e43\u003c/span\u003e]. The method we developed for creating durable bonds between rGO and metal alloys involves an initial surface treatment using an atmospheric pressure plasma jet (APPJ).\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eA thin layer of graphene flakes is then deposited, followed by a pulsed electric current process to permanently bond the graphene layer to the metal substrate (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). The thickness of the graphene layer depends on the deposition method and can range from a few nanometers to several micrometers.\u003c/p\u003e\n\u003cp\u003eIn the first stage, the metal surface is pretreated. To this end, the surface is cleaned with ethyl alcohol, then sanded with 120 grit sandpaper and polished with a diamond polishing pad using a grain size of 9 \u0026micro;m grain size. Finally, a polishing cloth with a 3 \u0026micro;m diamond paste is used. The maximum roughness of the polished surface did not exceed \u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e = 0.8 \u0026micro;m. This preliminary surface preparation step is not always necessary; it is sufficient to use the material as supplied if it has an appropriate roughness.\u003c/p\u003e\n\u003cp\u003eIn the next stage, the prepared surface is activated using a low-temperature argon plasma generation device. Plasma treatment is carried out for 120 seconds. The effect of plasma treatment is a significant increase in the surface free energy of the metal. The atmospheric pressure plasma jet system consists of a plasma head, which is composed of a negative electrode, a positive electrode, a dielectric located between them, and a gas supply system and a high-frequency voltage supply system for the plasma head. During low-temperature plasma generation, the plasma head is held at a distance of two centimeters from the surface of the metal being processed. If the surface of the metal being processed is large, a reciprocating motion of the plasma head should be applied to cover the entire surface of the metal being processed. A self-made atmospheric pressure plasma jet system with the following parameters was used: power 300 W, operating voltage 18 kV, operating frequency 25 kHz, argon flow rate 16 l/min, and constant exposure time of 120 seconds. During plasma treatment, the maximum temperature measured with a thermal imaging camera was 31\u0026deg;C.\u003c/p\u003e\n\u003cp\u003eNext, the metal surface on which the low-temperature atmospheric plasma was generated is coated with rGO flakes by using a dry method, collecting its excess to a specific thickness or wet, using graphene in the form of a solution in vinyl alcohol.\u003c/p\u003e\n\u003cp\u003eElectropulse treatment involves pressing a copper electrode with appropriate force onto the rGO layer on the metal, while simultaneously supplying a pulsed current from a power supply with a current of 1.9 kA. Positive rectangular current pulses with a duration of milliseconds were used. The pulsed current was supplied to the treated layer through an electrode with a tip size of 3x3 mm, pressed with a force of 20 N. The process is scalable; by replicating it, a larger surface area can be covered. Current pulses were delivered from developed current pulse generator equipped with a 1400 F supercapacitor battery and a current switch implemented using a MOSFET matrix. The current was generated in the form of a function generator in the form of \u003cem\u003et\u003c/em\u003e\u003csub\u003e\u003cem\u003ed\u003c/em\u003e\u003c/sub\u003e/\u003cem\u003et\u003c/em\u003e\u003csub\u003e\u003cem\u003ep\u003c/em\u003e\u003c/sub\u003e, where td is the duration of the pulse and \u003cem\u003et\u003c/em\u003e\u003csub\u003e\u003cem\u003ep\u003c/em\u003e\u003c/sub\u003e is a period. The power supply operating voltage was 2.55 V. As a result of this 3-second electropulse process, a permanent bond was formed between the rGO flakes and the metal substrate. In the study, a sample of Titanium Grade 2 in the form of a 2 mm thick sheet was used. To determine the influence of electropulse parameters on the final coating thickness, experimental investigations were conducted across varying current pulse durations (td), while maintaining a constant pulse period (tp) of 1000 \u0026micro;s. A direct correlation was observed: as the pulse duration increased, the thickness of the resultant 3D rGO coating exhibited a successive increase. The duration of the experimental current pulse \u003cem\u003et\u003c/em\u003e\u003csub\u003e\u003cem\u003ed\u003c/em\u003e\u003c/sub\u003e was determined to be 500 \u0026micro;s and the time \u003cem\u003et\u003c/em\u003e\u003csub\u003e\u003cem\u003ep\u003c/em\u003e\u003c/sub\u003e was 1000 \u0026micro;s, respectively. The process temperature measured with a thermocouple placed as close as possible to the edge of the electrode was 950\u0026deg;C. This is a much higher temperature than that obtained in a typical electroplastic process, because rGO has good electrical conductivity.\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eStructural characterizations\u003c/h3\u003e\n\u003cp\u003eTo characterize the structure of the rGO flakes used and the prepared layers on the Ti Grade 2 substrate, TEM analysis was performed using a Hitachi H800 microscope. A suspension of the powder in acetone was deposited on copper carbon grids and left to dry. The microstructure of the coatings was analyzed on Ti samples prepared by the FIB (Focused Ion Beam) method. Cross sections were obtained in two directions, parallel to the coating and substrate (orientation A) and perpendicular (orientation B). The results obtained were compared and analyzed to confirm the graphene phase using selected area electron diffraction (SAED) patterns. Using the Kat.Dyfr program, theoretical electron diffraction patterns were obtained for parameters defined according to the Pearson catalogue [\u003cspan class=\"CitationRef\"\u003e44\u003c/span\u003e] (a, b, c, \u0026alpha;, \u0026beta;, \u0026gamma;), which were then compared (overlapped) with the recorded images. The figures show a general view of the material under investigation observed in a Hitachi H800 microscope. The analysis of the particles showed that the rGO flakes varied in shape and size (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea). Electron diffraction patterns were obtained from the visible areas. Very good agreement was found both in terms of the defined interplanar distances and interplanar angles with the theoretical values. Differences in the determined values were below 0.001 nm and resulted from the measurement method used. Furthermore, it was found that the orientation of the graphite flakes recorded and the zone axis indices are as follows [uvw] = [100]. The results obtained confirm the presence of graphene in the investigated material. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb shows a view of the deposited rGO layer on the analyzed sample. The microstructure of the rGO coatings was analyzed in two cross sections, perpendicular to the coating and substrate, and parallel to the substrate (orientations A and B). Microstructure studies revealed a compact, granular structure of the rGO coating, exhibiting strong adhesion to the substrate (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ec). Furthermore, a fragmented structure of the substrate material was observed, marked by white lines in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ec. The coating exhibits a compact, dense, and pore-free structure with high adhesion to the substrate. Microstructure analysis performed on a cross-section of the coating revealed grains of varying sizes in the bonding zone, indicating changes in the substrate material as a result of coating deposition. The dominance of grains with oval and spheroidal crystal structures was observed (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ed). Depending on the direction of study, the formed coating exhibits different crystallographic orientations of the grains. In the cross section of the coating made in the second direction (orientation B), a plate-like structure dominates (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ee). The presence of individual graphene flake packages was observed (Fig.\u0026nbsp;3f). On the basis of the analysis of the recorded diffraction patterns, a very good agreement was found, both in terms of the defined interplanar distances and interplanar angles, with the theoretical values for the graphene phase. The studies confirmed the presence of graphene in the investigated coatings.\u003c/p\u003e\n\u003cp\u003eA dense and pore-free 3D rGO coating was obtained, which showed strong adhesion to the substrate. This is attributed, among other factors, to the high temperature experienced by the thin rGO layer during the process. The observed microstructure of the coating in the analyzed cross sections revealed that most of the rGO flake packages were oriented perpendicular to the observed surface. This orientation is a direct result of the deposition method, where the electric field acts on the rGO flakes in this particular direction.\u003c/p\u003e\n\u003ch3\u003eInvestigations of the metal surface condition after plasma treatment process\u003c/h3\u003e\n\u003cp\u003eTo assess the surface condition before and after plasma treatment, contact angle measurements were performed using the sessile drop method. This technique evaluates the interaction and spread of a test liquid droplet (Supplementary Table\u0026nbsp;1). Figure (Supplementary Fig.\u0026nbsp;2) shows a water droplet deposited on a Ti Grade 2 surface. The contact angle of the material in the received state of 74\u0026deg; indicates a certain degree of hydrophilicity of the substrate. As a result of plasma treatment of the Ti surface, a higher wettability of the substrate was achieved by water, with a contact angle of 43\u0026deg;. Additionally, Surface Free Energy (SFE) was calculated to assess the efficiency of cold plasma treatment. As shown in Supplementary Fig.\u0026nbsp;3, cold plasma treatment significantly increased the polar fraction of the SFE, resulting in an overall increase in the surface free energy of the tested specimen. This significant increase in the polar fraction of the SFE, approximately 100%, indicates an increase in the hydrophilicity of the surface exposed to low-temperature plasma, making it more reactive. The action of the active plasma likely resulted in surface cleaning by breaking the bonds of organic contaminants, which were subsequently oxidized and removed. The significant increase in the polar component of the surface free energy likely correlates with an increase in surface oxygen content. This is likely the primary factor contributing to the observed differences in surface energy between the untreated and plasma-treated specimens. To further investigate the factors contributing to the observed differences in surface free energy, X-ray photoelectron spectroscopy (XPS) was employed to analyze surface chemical changes induced by plasma treatment.\u003c/p\u003e\n\u003ch3\u003eCharacterization of the 3D rGO coating\u003c/h3\u003e\n\u003cp\u003eXPS was used to monitor the successive stages of rGO coating formation on the Ti Grade 2 surface. Surfaces rich in oxygen-hydrogen bonds exhibit higher surface energies, leading to improved adhesion. The primary objective of the XPS analysis was to investigate how plasma treatment of the titanium surface influences its initial adhesion and subsequent deposition of a robust graphene coating. In the first step, XPS was used to assess the effectiveness of low-temperature plasma beam treatment (with specific parameters) on the Ti Grade 2 surface, immediately prior to graphene deposition. In the second step, XPS was used to characterize the deposited carbon layer, specifically to determine its graphene-like nature.\u003c/p\u003e\n\u003cp\u003eXPS is a surface-sensitive, nondestructive analytical technique with high surface sensitivity. For example, the average inelastic mean free path (IMFP) for Ti 2p electrons in TiO\u003csub\u003e2\u003c/sub\u003e is 1.7 nm, while in C/CxOy layers it typically does not exceed 2.3 nm [\u003cspan class=\"CitationRef\"\u003e45\u003c/span\u003e]. Therefore, the sampling depth (3\u0026lambda;) and the calculated elemental composition will always apply to layers with thicknesses\u0026thinsp;\u0026lt;\u0026thinsp;8 nm (assuming the homogeneity of the analyzed layer).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSubstrate pretreatment. Plasma cleaning.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTable (Supplementary Table\u0026nbsp;2) presents the chemical composition of the Ti surface, mechanically pre-degreased and ground, before and after plasma beam exposure. Analysis revealed that both the raw and ground metallic Ti surfaces were covered by a layer of natural oxides, primarily composed of carbon (including oxygen-bound carbon) and titanium oxides. Nitrogen and calcium were also found on the surface of both samples. As suspected, mechanical grinding did not expose the metallic surface. The total elemental carbon content decreased slightly, from approximately 58 to 54 at. %, and the C: Ti ratio from 5.3 to 4.6, respectively. The general degree of surface oxidation did not change, O:Ti\u0026thinsp;=\u0026thinsp;2.6.\u003c/p\u003e\n\u003cp\u003eThe deconvolution of the C 1s spectra, presented in Fig.\u0026nbsp;3, revealed that the carbon bonding structure on the Ti surface before and after grinding was very similar, characteristic of a typical native passive coating on metallic titanium (Supplementary Table\u0026nbsp;2) [\u003cspan class=\"CitationRef\"\u003e46\u003c/span\u003e]. UV light and active oxygen species (radicals), generated within the atmospheric plasma, effectively disrupted the C-C(H) bonds of surface contaminants. After irradiating the Ti surface with a plasma beam, the total surface carbon content considerable decreased to about 16% at. (3.4 times). The bonding structure also underwent changes. The proportion of C-C(H) bonds decreased from 66% to 27%, while the abundance of oxygen-containing bonds increased. The fractions of C-O and C-O-H (13.1%), C\u0026thinsp;=\u0026thinsp;O and O-C-O (9.7%), and O-C\u0026thinsp;=\u0026thinsp;O (10.8%) were not substantially different from those observed in 'native' oxides on the Ti surface. However, two new forms of active surface oxygen emerged: CO2 (ads) (16.7%) and CO3-/O-C(O)-O (22.3%), with binding energies of 289.6 eV and 292.7 eV, respectively [\u003cspan class=\"CitationRef\"\u003e47\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eAlthough the elemental composition, as presented in Supplementary Table\u0026nbsp;2, represents the composition of layers only a few nanometers thick, it does not significantly reflect variations in the depth profile of these layers. The structure of the existing and newly formed carbon and oxide layer was modelled using QUASESTM analyze software for the excitation of Mg K\u0026alpha; [\u003cspan class=\"CitationRef\"\u003e48\u003c/span\u003e]. The results of the modelling for the plasma-modified Ti surface are presented in Fig.\u0026nbsp;3. In the initial step, the thickness of the overlayer, primarily composed of adventitious carbon, was determined by analyzing the Ti 2p region (Fig.\u0026nbsp;3d). The depth at which carbon and its compounds appeared was independently estimated based on the Auger C KLL region (Fig.\u0026nbsp;3e). Subsequently, the thickness of the oxide layer was modelled with 'Analyze' using the Auger OKLL region of the Mg K\u0026alpha; survey (Fig.\u0026nbsp;3f). The resulting carbon/oxide layer profile is illustrated in the bar diagram: the thickness of the TiO\u003csub\u003e2\u003c/sub\u003e (+\u0026thinsp;TiO\u0026thinsp;+\u0026thinsp;Ti\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e) layer was estimated to be 3.5 nm (at a depth of 1.5 to 5.0 nm). The outermost layer consisted of a 0.5 nm thick layer of contamination carbon (C-C/C-H) overlaid by COx bonds (1.5 nm). Given the high reactivity of Ti, it is highly probable that some of this carbon adsorbs onto the Ti surface even after plasma beam irradiation. Within a depth of 1.5 to 2.2 nm, both titanium oxides and COx groups were present in the modelled layer.\u003c/p\u003e\n\u003cp\u003eThe exact structure of the Ti bonds is depicted in Fig.\u0026nbsp;3. The figure shows high-resolution Ti 2p envelopes with their deconvolutions for the ground and degreased titanium surface (Fig.\u0026nbsp;3g) and after plasma beam irradiation (Fig.\u0026nbsp;3h). The fitting parameters for the Ti 2p peak were determined using averaged binding energy (BE) data and splitting data of 2p\u003csub\u003e1/2\u003c/sub\u003e \u0026minus;\u0026thinsp;2p\u003csub\u003e3/2\u003c/sub\u003e from the NIST XPS database [\u003cspan class=\"CitationRef\"\u003e49\u003c/span\u003e]. Furthermore, data from readily available standard samples (metal, TiO\u003csub\u003e2\u003c/sub\u003e) [\u003cspan class=\"CitationRef\"\u003e50\u003c/span\u003e] were used to refine peak widths, splitting (\u0026Delta;\u0026thinsp;=\u0026thinsp;6.05 eV for Ti(0), \u0026Delta;\u0026thinsp;=\u0026thinsp;5.72 eV for Ti(IV)), and shapes (asymmetric for the metallic component). The best fit was achieved by deconvoluting the Ti 2p spectrum into four components: TiO\u003csub\u003e2\u003c/sub\u003e, Ti\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, TiO and Ti(0), with Ti 2p\u003csub\u003e3/2\u003c/sub\u003e binding energies of 458.6, 457.2, 455.5, and 453.7 eV, respectively. A comparison of the Ti spectra before and after plasma beam irradiation reveals an increase in the overall oxidation state of Ti. The proportion of TiO\u003csub\u003e2\u003c/sub\u003e increased from 64.5% to 76.3%, while the fractions of other forms of Ti decreased: Ti\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e from 15.0 to 10.5%, TiO from 5.1 to 3.8%, and Ti(0) from 15.4 to 9.3%. Considering that Ti(0) resides beneath the TiO\u003csub\u003e2\u003c/sub\u003e layer, it is evident that plasma beam irradiation of the Ti surface resulted in a significant reduction in carbon contamination and an increase in the oxide layer thickness from 3 nm to approximately 5 nm (Fig.\u0026nbsp;3), primarily consisting of TiO\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e\n\u003ch3\u003eTesting of the deposited 3D rGO layer\u003c/h3\u003e\n\u003cp\u003eImmediately after plasma treatment, a layer of flake rGO was deposited onto the Ti surface using the procedure described above. XPS studies revealed that the actual substrate for graphene deposition was a TiO2 layer (rather than metallic Ti), at least 3 nm thick, overlain by a strongly adsorbed outermost layer of CxOy groups, estimated to be an additional 2 nm thick (Figs.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\n\u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e presents C 1s spectra for a Ti surface coated with a graphene layer, using the method described in this work. Reference spectra of the reduced GO used in this study, as well as commercial graphene (PCC Rokita), are also included. These reference samples helped identify carbon-carbon and carbon-oxygen bonds within the resulting layer. Graphene, along with other graphitic materials, exhibits a distinct main C 1s peak attributed to C\u0026thinsp;=\u0026thinsp;C, serving as a valuable reference. This peak is often assigned an energy of 284.5 eV. The binding energy of this peak is approximately 0.5 eV lower than that of aliphatic/contamination bonds (C-C, C-H). To ensure compatibility with previous studies in which the C 1s peak for carbon contamination at 284.8 eV was used as a reference energy, the C 1s binding energy for graphene (C\u0026thinsp;=\u0026thinsp;C) was set at 284.3 eV.\u003c/p\u003e\n\u003cp\u003eThe table (Supplementary Table\u0026nbsp;3) presents the fitting parameters for graphene and graphene-type materials, including the main peak asymmetry and \u0026pi; to \u0026pi;* shake-up satellite from a standard pure graphene / graphite sample. The deconvolution procedure was adapted from Biesinger's excellent work [\u003cspan class=\"CitationRef\"\u003e50\u003c/span\u003e], and the parameter values were refined on the basis of an owned spectrum (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ea) of commercial flake graphene (PCC Rokita). In Figs.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eb and \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ec, the C 1s spectra are shown for the flake rGO used in this work and the Ti surface, with the carbon coating deposited, and again using the deconvolution parameters shown in Table\u0026nbsp;3. To correctly position the C 1s spectrum for Ti with an applied carbon layer, BE 458.6 eV for Ti 2p\u003csub\u003e3/2\u003c/sub\u003e for an uncoated TiO\u003csub\u003e2\u003c/sub\u003e/Ti substrate after plasma irradiation was used as a reference (Fig.\u0026nbsp;3g).\u003c/p\u003e\n\u003cdiv class=\"BlockQuote\"\u003e\n\u003cp\u003eAnalyzing the results shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e, it was found that for the parent rGO, the total degree of oxidation/decomposition of its graphene monolayer structure, measured by CxOy / (C\u0026thinsp;=\u0026thinsp;C\u0026thinsp;+\u0026thinsp;sat), was 25% (versus 8% for pure commercial graphene). Exactly the same degree of oxidation/defect, characteristic of the rGO used, was calculated for the carbon layer obtained deposited on the Ti surface. Moreover, the position of the maximum dominant C 1s peak at 284.3 eV and its characteristic asymmetry are additional arguments that confirm that the obtained coating on Ti has a graphene (or more precisely, rGO) structure. In the C1s region, the presence of C-C and C-H bonds should also be noted. Although its share in rGO was only about 3%, on the rGO / TiO2/Ti surface analyzed, this share increased significantly to 33%.\u003c/p\u003e\n\u003c/div\u003e\n\u003cp\u003eThe XPS analysis revealed that at atmospheric pressure, low-temperature plasma treatment effectively removes the carbon content derived from contaminants on the material surface. Under atmospheric pressure, low-temperature plasma, high-energy ions collide with the sample surface, dissociate the carbon bonds in the contaminants, and cause them to volatilize.\u003c/p\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n\u003ch2\u003eCharacterization of the 3D rGO by Raman spectroscopy\u003c/h2\u003e\n\u003cp\u003eTo determine whether the 3D rGO deposition process caused significant changes in the structure of the original rGO, Raman spectroscopy was used. Raman spectroscopy is a powerful and nondestructive technique for characterizing graphitic materials such as graphenes, fullerenes and carbon nanotubes, and is also useful for distinguishing between pristine graphite, GO and rGO [\u003cspan class=\"CitationRef\"\u003e52\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e53\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e54\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e55\u003c/span\u003e]. In this study, Raman spectroscopy with a laser excitation wavelength of 514.5 nm was used to analyze the formed 3D rGO layer on Titanium Grade 2 (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e) and other different metallic supports (Supplementary Fig.\u0026nbsp;4).\u003c/p\u003e\n\u003cp\u003eThe Raman spectra of graphitic materials appear simple, they consist on a couple of very intense bands in the 1000\u0026ndash;2000 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e region and few other second-order modulations [\u003cspan class=\"CitationRef\"\u003e52\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e54\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e56\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e57\u003c/span\u003e]. The GO and rGO spectra are characterized by two intense bands: D and G, but they differ slightly in position and intensity [\u003cspan class=\"CitationRef\"\u003e53\u003c/span\u003e]. The G band represents the vibration mode in the plane of sp\u003csup\u003e2\u003c/sup\u003e-hybridized carbon atoms (the E\u003csub\u003e2g\u003c/sub\u003e phonon of C sp\u003csup\u003e2\u003c/sup\u003e atoms) and is characteristic of all samples containing sp\u003csup\u003e2\u003c/sup\u003e carbon networks [\u003cspan class=\"CitationRef\"\u003e52\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e53\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e57\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e58\u003c/span\u003e]. The D band at 1363 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is associated with structural defects and disorder in graphene structure (rings of the graphene layer) and indicates a reduction in the size of the sp\u003csup\u003e2\u003c/sup\u003e domains in the plane, e.g. due to extensive oxidation [\u003cspan class=\"CitationRef\"\u003e52\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e56\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e57\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e58\u003c/span\u003e]. Graphene with an ideal structure does not show D band [\u003cspan class=\"CitationRef\"\u003e57\u003c/span\u003e]. The ratio of the D and G band intensity (ID/IG) is a measure of the amount of disorder present within the material and is used for characterizing the defect quantity in graphitic materials [\u003cspan class=\"CitationRef\"\u003e52\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e53\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e59\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eGraphitic materials also exhibit a Raman band in the 2500\u0026ndash;2800 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e range. This band, known as the 2D band, corresponds to the overtone of the D band [\u003cspan class=\"CitationRef\"\u003e52\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e56\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e, the Raman spectrum of rGO exhibits a D-band at 1357 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, a G-band at 1597 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and three broad bands with low intensity in the 2500\u0026ndash;2850 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e range. The position of the D-band remains unchanged after the deposition of GO powder on Titanium Grade 2 (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e) and other metallic support (Supplementary Fig.\u0026nbsp;4). The G band shifts slightly (from 1357 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e to 1603 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) after deposition and this is observed for all samples tested. Larger band shifts are observed for rGO deposited on NiCr wire. In this case, the D band shifted from 1357 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e to 1416 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and the G band shifted from 1597 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e to 1655 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. This may be due to a different rGO coating deposition process. No G-band splitting was observed in any of the tested samples, which may indicate that rGO was not affected by randomly distributed defects [\u003cspan class=\"CitationRef\"\u003e57\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eThe I\u003csub\u003eD\u003c/sub\u003e/I\u003csub\u003eG\u003c/sub\u003e intensity ratio for the D and G-bands is widely used to characterize the quantity of defects in graphitic materials [\u003cspan class=\"CitationRef\"\u003e52\u003c/span\u003e]. The ID/IG intensity ratio correlates with the average size of the sp\u003csup\u003e2\u003c/sup\u003e domains and is frequently used to compare the degree of disorder and the size of the crystallite in graphitic layers [\u003cspan class=\"CitationRef\"\u003e55\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e58\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e59\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e60\u003c/span\u003e]. For GO samples, the intensity of the G band is typically higher than that of the D band. When GO is converted to a graphene network, the I\u003csub\u003eD\u003c/sub\u003e/I\u003csub\u003eG\u003c/sub\u003e intensity ratio increases as the sp\u003csup\u003e2\u003c/sup\u003e carbon network forms [\u003cspan class=\"CitationRef\"\u003e58\u003c/span\u003e]. In the rGO spectra and the prepared sample of rGO deposited on the Titanium Grade 2 and other support, the ID/IG intensity ratio of the rGO is higher than 1. The deposition process has no significant effect on this value.\u003c/p\u003e\n\u003cp\u003eDue to their broadness and low intensity, it is challenging to discern changes in the position of the bands in the 2500\u0026ndash;2850 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e range. The intensity of the 2D band is low compared to the D and G peaks. The shape of the 2D band is strongly dependent on the number of graphene layers in the sample, allowing Raman spectroscopy to differentiate between samples with a small number of sheets (1, 2, or more) [\u003cspan class=\"CitationRef\"\u003e52\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e54\u003c/span\u003e]. The G peak and another peak, called the G' band, which appears at approximately 2700 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, are characteristic of monolayer graphene in Raman spectra [\u003cspan class=\"CitationRef\"\u003e56\u003c/span\u003e]. An increase in the number of layers leads to a significant decrease in the intensity of 2D peaks, as observed in the prepared samples. Since the I\u003csub\u003e2D\u003c/sub\u003e/I\u003csub\u003eG\u003c/sub\u003e intensity ratio is less than 1 for all samples presented, it suggests a multilayered graphene structure for both the initial rGO and after its deposition on metallic supports [\u003cspan class=\"CitationRef\"\u003e54\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eBased on these observations, we can conclude that no significant reduction or other significant process occurred during the deposition of GO powders onto metallic supports. The structure of the GO powder remains unchanged, indicating that oxygen functional groups from the rGO are not removed during the deposition process.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eMechanical properties of the 3D rGO layers\u003c/h3\u003e\n\u003cp\u003eTo characterize the mechanical properties of the produced layer, nanoindentation tests were performed on a sample of WCLV tool steel coated with 3D rGO. Nanoindentation is a widely recognized technique for evaluating the local mechanical properties of thin coatings by observing the force-displacement behavior during the penetration of a diamond indenter with a defined geometry into the material\u0026rsquo;s surface [\u003cspan class=\"CitationRef\"\u003e61\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e62\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eThe test provides key parameters such as hardness and indentation modulus, which reflect the material\u0026rsquo;s ability to resist deformation and elastic recovery, respectively. Given the heterogeneous nature of the 3D rGO coating, the Grid Indentation Technique (GIT) was employed [\u003cspan class=\"CitationRef\"\u003e63\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e64\u003c/span\u003e]. The indentations were spatially targeted to a well-defined region of the 3D rGO layer deposited on WCLV tool steel. The target region was optically and morphologically identified prior to testing (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ea). A matrix of indentations was applied exclusively within the confirmed coating area to ensure that the derived mechanical properties reflect the intrinsic behavior of the rGO architecture. The tests were conducted using a Berkovich indenter under depth-controlled indentation, with maximum penetration depth set at 200 nm and indent spacing of 10 \u0026micro;m (center-to-center). The selected maximum depth ensures that the influence zones of adjacent indents remain non-overlapping, preserving the statistical independence of measurements. The indentation depth was also selected to probe predominantly within the coating volume, given its thickness in the micrometer range.\u003c/p\u003e\n\u003cp\u003eFigures \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003eb and \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ec show contour maps of the spatial distribution of the indentation modulus (E\u003csub\u003eIT\u003c/sub\u003e) and hardness (H\u003csub\u003eIT\u003c/sub\u003e), respectively. These maps reveal a distinct mechanical response across the coating, with a central region displaying elevated mechanical properties\u0026mdash;consistent with effective flake alignment and densification. Peripheral zones showed slightly reduced values, suggesting microstructural heterogeneity, possibly related to variation in local flake orientation or layer thickness.\u003c/p\u003e\n\u003cp\u003eThe statistical correlation between hardness and indentation modulus is plotted in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ed. The majority of measurements cluster around values consistent with dense rGO-based architectures (E\u003csub\u003eIT\u003c/sub\u003e = 200\u0026ndash;400 GPa; H\u003csub\u003eIT\u003c/sub\u003e = 10\u0026ndash;30 GPa), but several data points display extreme values, with E\u003csub\u003eIT\u003c/sub\u003e exceeding 500 GPa and H\u003csub\u003eIT\u003c/sub\u003e approaching 45 GPa. These outliers likely correspond to localized domains of well-aligned, few-layer rGO flakes, what also aligns with values reported in the literature for high-quality graphene layers [\u003cspan class=\"CitationRef\"\u003e65\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e66\u003c/span\u003e]. Histogram insets illustrate the distribution of mechanical properties, confirming a non-Gaussian distribution skewed toward high-modulus and high-hardness tails.\u003c/p\u003e\n\u003ch3\u003eTesting the adhesion of 3D rGO to substrates\u003c/h3\u003e\n\u003cp\u003eBeyond evaluating the mechanical properties of the 3D rGO layer, an additional objective was to assess the adhesion of the graphene coatings produced to various metal surfaces. The testing protocol involved performing 1 mm-long scratch tests on three different samples: titanium Grade 2 (Ti), ASI 304 (SS)stainless steel, and tool steel (WCLV). During the tests, a constant normal force of \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eN\u003c/em\u003e\u003c/sub\u003e=2000 mN was applied. Additionally, for the titanium sample, a sequential scratch test was conducted to determine whether repeated passes of the indenter would cause delamination of the graphene from the substrate. Scratch locations were chosen along the boundary between the 3D rGO coating and the substrate material for all samples. Detailed panoramic images of the tested areas are shown in Figs.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ea-c. The scratch direction was set from the 3D rGO-coated surface towards the bare substrate.\u003c/p\u003e\n\u003cp\u003eUpon completion of the initial analysis, it was observed that in none of the cases graphene flakes were visibly detached from the surface, indicating a good adhesion between the 3D rGO coating and the tested substrates. In the case of stainless steel, a slight residue of graphene was visible on the underlying surface. No cracks or defects were observed in the 3D rGO layer in the initial stages of the scratch test. The surface of WCLV shows a smoother transition during the scratch test, indicating a better resistance to deformation or delamination under these conditions.\u003c/p\u003e\n\u003cp\u003eFor the sequential scratch test, the procedure involved the performing of 18 successive scratches of 800 \u0026micro;m length, applying a constant normal force of \u003cem\u003eF\u003c/em\u003e\u003csub\u003e\u003cem\u003eN\u003c/em\u003e\u003c/sub\u003e = 500 mN, along a predefined measurement path. As in the previous tests, the scratch path was positioned at the boundary between the 3D rGO coating and the titanium substrate. Each successive pass of the scratch tester began at the same starting point, allowing for the observation of changes in the penetration depth of the indenter. These changes were influenced solely by the evolving mechanical properties of the surface, excluding the effects of the surface morphology.\u003c/p\u003e\n\u003cp\u003eThe selected area and longitudinal scratch profiles are shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ed. Figures are presented in a scale that identifies the \"transition point\" from the titanium surface to the 3D rGO coating at \u003cem\u003eX\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.34 mm. Furthermore, variations in the penetration depth with successive passes are recorded and displayed in the accompanying figure (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ee).\u003c/p\u003e\n\u003cp\u003eThe increase in both frictional forces (orange) and penetration depth (black) is evident once the scratch tester transitions from the titanium substrate to the 3D rGO coating at \u003cem\u003eX\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.34 mm. The lack of significant penetration or delamination during subsequent passes suggests that the 3D rGO layer effectively resists wear, maintaining strong adhesion throughout the test.\u003c/p\u003e\n\u003cp\u003eThe presence of graphene after scratch tests was also confirmed by Raman spectroscopy. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e shows the Raman spectra measured for the WCLV steel sample in different places: in the test trace (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e) A and B areas scratched, C area - not damaged during the test.\u003c/p\u003e\n\u003cp\u003eThe first observed difference between these spectra is the different intensities of the D and G bands. The D bands measured for rGO inside the scratch test trace have slightly lower intensity than the G bands. The same D bands measured for rGO in the area not damaged during the scratch test show larger intensity than G band, similarly to the spectra obtained for the measurements of the tested steels: Ti Grade 2, 316L and WCLV, and also rGO powder (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e in the text and Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e in the Supplementary) before the scratch tests. The obtained values of the I\u003csub\u003eD\u003c/sub\u003e/I\u003csub\u003eG\u003c/sub\u003e intensity ratio for individual measurement points are as follows: 1.00 (A and B) and 1.06 (C), so this intensity ratio value is slightly lower for rGO measured in the scratch test area. The I\u003csub\u003eD\u003c/sub\u003e/I\u003csub\u003eG\u003c/sub\u003e intensity ratio is used to characterize the amount of defects in graphene materials, and increase when GO is converted into a graphene lattice, more ordered structure [\u003cspan class=\"CitationRef\"\u003e60\u003c/span\u003e]. In the presented WCLV sample, the value of the I\u003csub\u003eD\u003c/sub\u003e/I\u003csub\u003eG\u003c/sub\u003e intensity ratio decreases after the scratch test, which may suggest some changes in the structure caused by mechanical action. Therefore, during the scratch test, no destruction and delamination of the rGO layer is observed, but the rGO structure is less ordered.\u003c/p\u003e\n\u003cp\u003eFor the further interpretation of scratch test data, mean contact pressure p\u003csub\u003em\u003c/sub\u003e was estimated using the classical expression for a spherical indenter under normal load [\u003cspan class=\"CitationRef\"\u003e67\u003c/span\u003e]:\u003c/p\u003e\n\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\n\u003cdiv id=\"FileID_Equ1\" class=\"mathdisplay\"\u003e$$\\:{p}_{m}=\\frac{3FN}{2\\pi\\:{a}^{2}}\\:\\:,$$\u003c/div\u003e\n\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\n\u003c/div\u003e\n\u003cp\u003ewhere \u003cem\u003ea\u003c/em\u003e is the contact radius, approximated by Hertzian contact mechanics:\u003c/p\u003e\n\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\n\u003cdiv id=\"FileID_Equ2\" class=\"mathdisplay\"\u003e$$\\:a=\\sqrt[3]{\\frac{3FN}{8}\\bullet\\:\\frac{\\frac{1-{v}_{i}^{2}}{{E}_{i}}+\\frac{1-{v}_{s}^{2}}{{E}_{s}}}{\\frac{1}{{d}_{i}}+\\frac{1}{{d}_{s}}}}$$\u003c/div\u003e\n\u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\n\u003c/div\u003e\n\u003cp\u003eCalculating an effective modulus for different substrates under the consideration (E\u003csub\u003es\u003c/sub\u003e\u0026asymp;105\u0026ndash;220 GPa) and knowing the tip radius \u003cem\u003eR\u003c/em\u003e\u0026thinsp;=\u0026thinsp;100 \u0026micro;m, one can estimate \u003cem\u003ep\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e within the range of 4.84\u0026ndash;7.28 GPa for the FN\u0026thinsp;=\u0026thinsp;500mN and 7.69\u0026ndash;11.55 GPa for the FN\u0026thinsp;=\u0026thinsp;2000mN respectively. These values exceed typical interfacial adhesion limits for physisorbed graphene, further confirming that the strong bonding observed.\u003c/p\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n\u003ch2\u003eTesting the mechanical connection between 3D rGO and substrate\u003c/h2\u003e\n\u003cp\u003eIn this study, a nickel-chromium alloy was chosen as the substrate for the deposited 3D rGO layer, in contrast to the titanium, stainless steel and tool steel studied previously. To investigate the quality of the 3D rGO-NiCr bond, a set-up was developed to perform mechanical tests of this bond under tensile and compressive loading. A key element of this setup is a novel method to connect and load a free-standing rGO layer with the chosen metal. The studied rGO layer was deposited on the surface of square-shaped wires (0.8 mm side length) made of NiCr alloy, 83 mm apart. The resulting layer connected both the wires and the space between them (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003e).\u003c/p\u003e\n\u003cp\u003eThe width of the copper electrode used covered both wires. If the distance between the wires was too large, the rGO would not self-connect. The successful deposition of the layer enables the determination of the coating's properties under tensile and compressive loads, as well as the assessment of the quality of the 3D rGO-NiCr bond.\u003c/p\u003e\n\u003cp\u003eTo investigate the mechanical deformations of the rGO-NiCr interface, tests were performed using a custom-built testing rig (Supplementary Fig.\u0026nbsp;6) that enables compression and tension testing of the 3D rGO layer while keeping one NiCr wire stationary and allowing the other to move. This setup allows for measurements of resistance, voltage, temperature, and deformation.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\n\u003ch2\u003eThermal compression and tension testing of the 3D rGO layer\u003c/h2\u003e\n\u003cp\u003eThe distance between two parallel NiCr wires, one of which is stationary, can be adjusted using a thermal method. The temperature gradient created between the wires causes a change in the position of one of the wires because of its thermal expansion. As a result of temperature changes, the rGO undergoes compression or tension. The lower NiCr wire (Supplementary Fig.\u0026nbsp;6) is heated using a resistive heating element. It was observed that the resistance of the 3D rGO-NiCr connection changes over a wide range, from fractions of an ohm to several hundred kilohms, as the wires move relative to each other. To measure low resistance values, a four-probe method was used (Supplementary Fig.\u0026nbsp;7), which minimizes the influence of additional measurement errors related to the resistance of the leads. Measurements were carried out at a humidity of 40% and a temperature of 294 K. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003ea shows the effect of the temperature gradient on changes in the resistance of the connection.\u003c/p\u003e\n\u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003ea shows the initial state at a temperature of 294 K, characterized by a high resistance that exceeds 1500 W. As the temperature increases, the resistance gradually decreases to a steady-state value of 1350 Ω, followed by a sudden drop. Immediately after the transition to a low resistance state, oscillatory changes in resistance can be observed, which subsequently diminish. When the temperature is heated to the final temperature, the connection resistance reaches approximately 0.5 Ω. During the cooling process, a transition state and oscillations are also observed, with the difference being the presence of temperature hysteresis. Analyzing Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003ea, it should be noted that the initial resistance and the final resistance during the cooling process are similar, despite the presence of hysteresis. This indicates that the rGO-NiCr connections return to their initial state, also in terms of mechanical properties. However, the thermal method has limitations in terms of the maximum achievable deformation. In summary, this stage of the research suggests that it is not so much the temperature change that causes the resistance change of the rGO-NiCr connection, but rather the stretching or compression of the 3D rGO layer. To verify this hypothesis, an additional experiment was conducted, which directly reflects the change in deformation as a function of resistance and simultaneously constitutes a second research method related to the mechanical deformation of the rGO-NiCr connection.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\n\u003ch2\u003eMechanical compression and tension testing of the 3D rGO layer\u003c/h2\u003e\n\u003cp\u003eTo change the distance between two parallel NiCr wires, a mechanical method can also be employed. Measurements were carried out using a micrometer with an additional worm gear, providing a hundred-fold increase in strain resolution. The limitation of maximum strain, present in the thermal method, is absent in the mechanical method. Tests can be conducted over a wide range of strains until the 3D rGO layer ruptures. Measurements of resistance changes as a function of mechanical strain were made in both directions, that is, during compression and tension. In Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003eb, similar to Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003ea, three regions can be distinguished, each with a different sensitivity s. The average sensitivity s can be expressed as the ratio of the change in resistance \u0026Delta;R to the change in strain \u0026Delta;\u0026epsilon;, represented by the formula\u003c/p\u003e\n\u003cdiv id=\"Equ3\" class=\"Equation\"\u003e\n\u003cdiv id=\"FileID_Equ3\" class=\"mathdisplay\"\u003e$$\\:s=\\frac{\\varDelta\\:R}{\\varDelta\\:{\\epsilon\\:}}\\:\\:\\:\\left[\\frac{}{\\text{%}}\\right]$$\u003c/div\u003e\n\u003cdiv class=\"EquationNumber\"\u003e3\u003c/div\u003e\n\u003c/div\u003e\n\u003cp\u003e.\u003c/p\u003e\n\u003cp\u003eIn the first operating range (1) shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003eb, the resistance value increases, and the calculated sensitivity is \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{s}_{1}=0.20\\:\\frac{}{\\text{%}}\\)\u003c/span\u003e\u003c/span\u003e. The second range (2), referred to as the high-sensitivity state, indicates a change in the operating state of rGO and covers a strain range of 4\u0026ndash;10%, with a sensitivity of\u003c/p\u003e\n\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{s}_{2}=7200\\:\\frac{}{\\text{%}}\\)\u003c/span\u003e\u003c/span\u003e. In this range, the resistance value increases sharply, which can be explained by changes in the number of connections between rGO and NiCr. The third range (3) corresponds to a low-resistance state and is relatively narrow, with a low sensitivity of approximately \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{s}_{3}=0.15\\:\\frac{}{\\text{%}},\\)\u003c/span\u003e\u003c/span\u003e similar to the first range. The above division into ranges can also be explained by analyzing the structure of rGO during compression and tension. The rGO used in this solution can be treated as a network of resistors, which changes depending on the contact surface between the rGO and NiCr. With significant compression of the wires (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e11\u003c/span\u003ea), the contact surface between 3D rGO and the metal can be considered uniform, which means that there are no empty spaces between graphene and the wire.\u003c/p\u003e\n\u003cp\u003eThe tighter the connection, the more \u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003ee\u003c/em\u003e1\u003c/sub\u003e connections there will be, and the lower the value of the resultant resistance will be. As can be seen from the presented model, this will be a parallel connection of \u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003eg\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003ee\u003c/em\u003e1\u003c/sub\u003e, resistances, which can be described by the formula \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{R}_{Z}={R}_{e1}{R}_{g1}/\\left({R}_{e1}{+R}_{g1}\\right)\\)\u003c/span\u003e\u003c/span\u003e. Taking into account that the resistance value of rGO is small [\u003cspan class=\"CitationRef\"\u003e68\u003c/span\u003e], the resistance values observed are mainly caused by the change in the structure of the 3D rGO - NiCr connection. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e11\u003c/span\u003eb shows the situation representing the range (2) from Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003eb. As the strain (stretching) increases, the resistance value increases because the number of 3D rGO - NiCr connections begins to decrease - microcracks appear in the structure of the connection. The structure of the resistor connections changes to a 3-layer one, because we can distinguish the outer \u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003ee\u003c/em\u003e2\u003c/sub\u003e and inner rGO \u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003eg\u003c/em\u003e2\u003c/sub\u003e layers. It should be noted that the resistance \u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003eg\u003c/em\u003e2\u003c/sub\u003e of the rGO itself may change lightly; therefore, the change in resistance is due to the number of 3D rGO - NiCr connections. The fewer these connections, the higher the value of the resultant resistance will be. Such a structure can be described by the equation \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{R}_{Z}={R}_{e21}+{R}_{e22}+{R}_{g2}\\)\u003c/span\u003e\u003c/span\u003e.\u003c/p\u003e\n\u003cp\u003eThe mechanical properties of rGO cause that at a certain strain, further breaking of the 3D rGO - NiCr connection covers other areas (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e11\u003c/span\u003ec), which corresponds to the high resistance state (range (3) from Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003eb). The resistance in this range is expressed by the formula \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{R}_{Z}={R}_{e31}+{R}_{e32}+{R}_{g3}\\)\u003c/span\u003e\u003c/span\u003e. The relationship between the resistance values \u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003eg\u003c/em\u003e\u003c/sub\u003e for individual ranges is presented as \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{R}_{g1}\u0026lt;{R}_{g2}\u0026lt;{R}_{g3}\\)\u003c/span\u003e\u003c/span\u003e, while these changes are small. The relationship between the resistance values Re for individual ranges \u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003ee\u003c/em\u003e1\u003c/sub\u003e≪\u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003ee\u003c/em\u003e2\u003c/sub\u003e≪\u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003ee\u003c/em\u003e3\u003c/sub\u003e, and these changes are visible in state 3 of high resistance. The above analysis of the resistance behavior of the 3D rGO - NiCr connection explains both the changes visible in the microscopic images (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e11\u003c/span\u003e) and the changes in resistance values observed during tests carried out by the thermal and mechanical methods (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e). Taking into account the construction of the test stand and the properties of rGO, it can be concluded that the 3D rGO - NiCr connection is broken mainly at the contact with the metal. It was also noted in [\u003cspan class=\"CitationRef\"\u003e69\u003c/span\u003e] that graphene has a small negative temperature coefficient of about 1.5 \u0026sdot;10\u003csup\u003e\u0026minus;3 o\u003c/sup\u003eC \u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Comparing the above values with the results obtained by the authors, it is concluded that the influence of temperature is negligible in relation to the measured resistance changes related to the rGO strain.\u003c/p\u003e\n\u003cp\u003eThe oscillations observed by the authors shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003ea can be explained as a quantum interference phenomenon that occurs between individual layers of graphene [\u003cspan class=\"CitationRef\"\u003e70\u003c/span\u003e] that becomes apparent and visible during the compression process at small resistance values after the occurrence of the cooling transient state and before the occurrence of the heating transient state.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\n\u003ch2\u003ePotential application of 3D rGO coating on cemented carbide tool inserts for turning process\u003c/h2\u003e\n\u003cp\u003eTurning trials were conducted using turning inserts (WNMG080408-LP) coated with the developed 3D rGO layer (current pulse durations \u003cem\u003et\u003c/em\u003e\u003csub\u003e\u003cem\u003ed\u003c/em\u003e\u003c/sub\u003e = 200\u0026micro;s, and constant pulse period \u003cem\u003et\u003c/em\u003e\u003csub\u003e\u003cem\u003ep\u003c/em\u003e\u003c/sub\u003e = 1000 \u0026micro;s). These were compared against commercially available titanium aluminum nitride (TiAlN) PVD coatings of the MC6025 type. The selected inserts feature a specific geometry optimized for steel turning applications, and their LP chip breaker geometry is specifically designed for light to medium turning operations, facilitating effective chip control and reducing cutting forces. The primary objective of these studies was to assess the performance and durability of the tools under controlled machining conditions using C45 steel. The study aimed to determine the influence of the coating type on tool life and machining efficiency, which are critical factors for optimizing machining processes and reducing production costs.\u003c/p\u003e\n\u003cp\u003eThe workpiece material chosen for the study was commercial C45 steel, designated according to PN-EN 10083-2. C45 steel is an unalloyed quality steel suitable for heat treatment, characterized by a medium carbon content. In its softened state, C45 steel exhibits a hardness of approximately 220 HB, while after heat treatment, its hardness can range from 55 to 60 HRC. Cylindrical bars with an initial length of 100 mm and a diameter of 30 mm were used for the experimental turning operations. The objective of the machining process was to reduce the diameter of these bars to 10 mm, allowing for observation of tool wear under controlled and consistent conditions.\u003c/p\u003e\n\u003cp\u003eAll turning experiments were performed on a DMG MORI CLX350V4 Computer Numerical Control (CNC) lathe. This machine tool is characterized by high precision and dynamic machining capabilities. The lathe is equipped with a main spindle capable of achieving a maximum rotational speed of 5000 rpm and a spindle drive power of 16.5 kW. The inherent stability and rigidity of this machine ensure consistent machining conditions, which are crucial for obtaining reliable and repeatable results in tool wear studies.\u003c/p\u003e\n\u003cp\u003eThe turning process was carried out using the following controlled parameters: cutting speed \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ec\u003c/em\u003e\u003c/sub\u003e = 100 m/min, feed rate \u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.15 mm/rev, depth of cut \u003cem\u003ea\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.5 mm. With a depth of cut of 1.5 mm per side, the total radial reduction was 10 mm (from a 15 mm radius to a 5 mm radius). This required 7 cutting passes. Consequently, the total cutting path traversed by the tool during the entire machining operation for one sample was 700 mm.\u003c/p\u003e\n\u003cp\u003eThe initial phase of our investigation focused on characterizing the delamination behavior of the PVD coating. We observed that the PVD coating was removed after just the first cutting pass (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e11\u003c/span\u003ea), while the 3D rGO coating remained intact. Visual observations, supplemented by microscopic analyses, were used to identify the exact point at which either the graphene or PVD coatings showed signs of damage or complete delamination.\u003c/p\u003e\n\u003cp\u003eThe tool wear criterion was established as reaching a flank wear value of 0.3 mm, significant deterioration of the machined surface quality, an increase in cutting forces, the onset of vibrations, or catastrophic tool failure. Regular measurements of tool wear and a comprehensive analysis of the machined surface quality allowed for continuous monitoring of wear progression. The data collected from this test enabled a direct comparison of tool life for both coating types, facilitating an assessment of the graphene coating's effectiveness in extending tool life under prolonged machining conditions.\u003c/p\u003e\n\u003cp\u003eThe established wear limit for the PVD-coated insert occurred after 14 cutting passes (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e11\u003c/span\u003eb).\u003c/p\u003e\n\u003cp\u003eIn contrast, the 3D rGO-coated insert wore out after 21 cutting passes. These results demonstrated that inserts incorporating the graphene coating exhibited increased wear resistance, leading to extended tool life and potentially reduced production costs. Considering their unique properties, such as high hardness, low friction coefficient, and chemical inertness, graphene coatings possess transformative potential to revolutionize machining technology. Their integration is expected to lead to significant performance improvements, a considerable reduction in tool wear, and an overall increase in the quality of machined surfaces, thereby pushing the boundaries of conventional manufacturing.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eA novel method for depositing 3D rGO onto metals has been developed, utilizing low-temperature atmospheric plasma combined with electropulse treatment. This method is fully scalable, has been applied to various metal alloys, and can be conducted under ambient conditions. The 3D rGO layer demonstrated strong adhesion to the substrate, as evidenced by TEM images, and exhibited a dense, pore-free structure with most rGO flakes oriented perpendicular to the surface. XPS analysis revealed that after plasma treatment, the carbon content on the Ti surface decreased significantly, while the oxygen content doubled. This indicates the formation of a thicker TiO\u003csub\u003e2\u003c/sub\u003e layer and increased surface oxygenation, enhancing the adhesion of the graphene-like coating. The C 1s spectra of both the pristine rGO flakes and the deposited 3D rGO layer exhibited striking similarities, suggesting a graphene-like structure for the coating and explaining its high hardness. Nanoindentation tests demonstrated a significant enhancement in the mechanical properties of the titanium substrate due to the 3D rGO coating. The average hardness and indentation modulus of the coated surface were higher than those of the uncoated substrate, indicating the contribution of the graphene layer to the increased stiffness and resistance to deformation. Notably, certain regions within the coating exhibited exceptionally high hardness and modulus values, aligning with those reported for high-quality graphene. The adhesion of 3D rGO coatings to various metal substrates was evaluated by scratch testing, which revealed strong adhesion without visible delamination. Sequential scratch testing on titanium samples demonstrated the excellent wear resistance and adhesion of the coating under repeated mechanical loading. To further understand the rGO-metal bond, tensile and compressive tests were conducted on the 3D rGO layer. The results confirmed a strong adhesion between the layer and the substrate, with the 3D rGO layer exhibiting a maximum strain of up to 30% before failure, without complete detachment from the metal. This suggests potential applications in various electronic sensors due to the layer's high sensitivity. The durable 3D rGO coatings produced using this scalable method offer numerous practical applications that leverage graphene's unique properties, particularly its exceptional mechanical strength. Potential applications include coatings for tools used in various manufacturing processes. It was experimentally demonstrated during the turning process that the tool wear of the 3D rGO-coated insert increased by 150% compared to the PVD-coated insert, which we consider a significant success. During the turning process, under sustained cyclic loading and high temperatures, the applied layer remains undamaged throughout the tool's full working cycle. The strong bond between graphene and metal has significant implications for engineering applications where graphene is first time used as a robust bulk layer rather than a previously used component of composite materials or porous structures.\u003c/p\u003e\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\u003cdiv id=\"Sec17\" class=\"Section3\"\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"Methods","content":"\u003ch2\u003eMaterials\u003c/h2\u003e\u003cp\u003eFew-layer graphene oxide was obtained from Nanomaterials (Poland), prepared by a modified Hummers method using commercially available natural graphite with 99.0% purity (Acros Organics, USA, 325 mesh). Reduced graphene oxide exhibited a stacked nanostructure with an average lateral dimension of approximately 8 nm and a height of approximately 1 nm, with an interlayer spacing of 0.4 nm between 2–3 graphene layers [\u003cspan citationid=\"CR71\" class=\"CitationRef\"\u003e71\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThis study used sheet samples of Grade 2 Commercial Pure Titanium (ASTM B 265) with a thickness of 2 mm (HWN titan GmbH, Germany), tool steel (1.2344) WCLV with a thickness of 3.6 mm, austenitic stainless steel AISI 304 with a thickness of 0.5 mm, and Ni90Cr10 (Chromel) wire with a diameter of 0.8 mm.\u003c/p\u003e\u003ch2\u003eCharacterization\u003c/h2\u003e\u003cp\u003eThe preparation of the sample for microstructural analysis was performed using a dual beam FIB-SEM/XE-PFIB FEI HELIOS G4 PFIB CXE. Observations were carried out using a Hitachi H800 transmission electron microscope equipped with a Qumesa CCD camera, a Keyence VHX-6000 optical microscope and a Sigma 500VP scanning electron microscope.\u003c/p\u003e\u003cp\u003eX-ray photoelectron spectroscopy (XPS) measurements were performed using a SPECS PHOIBOS 100 spectrometer. Both the Mg (1253.6 eV) and Al (1486.6 eV) anodes, operating at 250 W, were used for high-resolution spectra acquisition. The obtained spectra were fitted with Gaussian-Lorentzian curve profiles after subtracting a Shirley background using CasaXPS v.2.3.19 software. The reported binding energies have an accuracy of ± 0.1 eV. All binding energies were referenced to the C 1s peak at 284.8 eV. Additionally, the 3D structures of the surface layer were modelled using Quases™ 'Analyze' software [\u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e72\u003c/span\u003e]. A 'buried layer' model was employed to interpret the morphology of the analyzed layers. This class of 3D profiles can be used to model a wide variety of solids, including substrates with an overlayer, an overlayer on a substrate, a buried layer, and homogeneous solids.\u003c/p\u003e\u003cp\u003eRaman spectra were acquired using a Horiba Jovin Yvon HR800 UV spectrometer. All nanoindentation tests were performed using an Anton-Paar UNHT3 ultrananoindenter equipped with a Berkovich indenter tip. To achieve this, standardized adhesion testing methods were employed, specifically scratch testing using the Anton-Paar MCT3 apparatus equipped with a Rockwell diamond indenter with a spherical radius of 100 µm.\u003c/p\u003e\u003cp\u003eElectrical measurements were made using the following equipment: resistance – Agilent 34420A, voltages – Agilent 34401A, power supply – Hewlett Packard E3631A, oscilloscope – LeCroy LT224. Temperature measurements were acquired using a Hewlett-Packard 34970A with a type K thermocouple.\u003c/p\u003e\u003cp\u003eAll turning experiments were performed on a DMG MORI CLX350V4 Computer Numerical Control (CNC) lathe.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eFunding\u003c/h2\u003e\u003cp\u003eOpen access funding provided by Wroclaw University of Science and Technology.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eZ.Z. conceived the idea and supervised the project, fabricated devices and 3D rGO samples, performed a resistance measurement during tensile tests, and wrote the manuscript. W.T. performed XPS analysis. B.B. performed Raman measurements. M.P. carried out the mechanical testing and scratch test. M.R.G. performed the electron microscopy characterization. R.W. carried out the contact angle measurements. K.K. performed the turning process. D.D. performed a resistance measurement during tensile tests. All authors discussed and interpreted the results and contributed to the writing of the manuscript.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe main datasets generated and analysed during the current study are available in the repository [https://doi.org/10.18150/BMOIZM](https:/doi.org/10.18150/BMOIZM) , RepOD. More data are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eLee, C., Wei, X., Kysar, J. W. \u0026amp; Hone, J. Measurement of the elastic properties and intrinsic strength of monolayer graphene. \u003cem\u003eScience\u003c/em\u003e \u003cb\u003e321\u003c/b\u003e, 385\u0026ndash;388 (2008).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGeim, A. K. Graphene: status and prospects. \u003cem\u003eScience\u003c/em\u003e \u003cb\u003e324\u003c/b\u003e, 1530\u0026ndash;1534 (2009).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhu, Y. et al. Graphene and graphene oxide: synthesis, properties, and applications. \u003cem\u003eAdv. Mater.\u003c/em\u003e \u003cb\u003e22\u003c/b\u003e, 3906\u0026ndash;3924 (2010).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRamezani, M. J. \u0026amp; Rahmani, O. A review of recent progress in the graphene syntheses and its applications. \u003cem\u003eMech. Adv. Mater. Struct.\u003c/em\u003e, 1\u0026ndash;33 (2024).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eStrupiński, W. et al. Baranowski. Graphene epitaxy by Chemical Vapor Deposition on SiC. \u003cem\u003eNano Lett.\u003c/em\u003e \u003cb\u003e11\u003c/b\u003e, 1786\u0026ndash;1791 (2011).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYan, Z. et al. Toward the synthesis of wafer-scale single-crystal graphene on copper foils. \u003cem\u003eACS Nano\u003c/em\u003e. \u003cb\u003e6\u003c/b\u003e, 9110 (2012).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHao, Y. et al. The role of surface oxygen in the growth of large single-crystal graphene on copper. \u003cem\u003eScience\u003c/em\u003e \u003cb\u003e342\u003c/b\u003e, 720\u0026ndash;723 (2013).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLevy, N. et al. Crommie. Strain-induced pseudo magnetic fields greater than 300 Tesla in graphene nanobubbles. \u003cem\u003eScience\u003c/em\u003e \u003cb\u003e329\u003c/b\u003e, 544 (2010).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChen, W. \u0026amp; Yan, L. Situ Self-Assembly of Mild Chemical Reduction Graphene for Three-Dimensional Architectures. \u003cem\u003eNanoscale\u003c/em\u003e \u003cb\u003e3\u003c/b\u003e, 3132\u0026ndash;3137 (2011).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eEstevez, L., Kelarakis, A., Gong, Q., Da\u0026rsquo;as, E. H. \u0026amp; Giannelis, E. P. Multifunctional Graphene/Platinum/Nafion Hybrids via Ice Templating. \u003cem\u003eJ. Am. Chem. Soc.\u003c/em\u003e \u003cb\u003e133\u003c/b\u003e, 6122\u0026ndash;6125 (2011).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eXu, Z. \u0026amp; Gao, C. Graphene Chiral Liquid Crystals and Macroscopic Assembled Fibres. \u003cem\u003eNat. Commun.\u003c/em\u003e \u003cb\u003e2\u003c/b\u003e, 571 (2011).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLin, Y. M. et al. Ph. 100-GHz transistors from wafer-scale epitaxial graphene. \u003cem\u003eScience\u003c/em\u003e \u003cb\u003e327\u003c/b\u003e, 662 (2010).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChen, K. W., Chen, L. B., Chen, Y. Q., Bai, H. \u0026amp; Li, L. Three-Dimensional Porous Graphene-Based Composite Materials: Electrochemical Synthesis and Application. \u003cem\u003eJ. Mater. Chem.\u003c/em\u003e \u003cb\u003e22\u003c/b\u003e, 20968\u0026ndash;20976 (2012).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eEl-Kady, M. F., Strong, V., Dubin, S. \u0026amp; Kaner, R. B. Laser Scribing of High-Performance and Flexible Graphene-Based Electrochemical Capacitors. \u003cem\u003eScience\u003c/em\u003e \u003cb\u003e335\u003c/b\u003e, 1326\u0026ndash;1330 (2012).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJakus, A. E. et al. Three-Dimensional Printing of High-Content Graphene Scaffolds for Electronic and Biomedical Applications. \u003cem\u003eACS Nano\u003c/em\u003e. \u003cb\u003e9\u003c/b\u003e, 4636\u0026ndash;4648 (2015).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhang, Y. et al. Broadband and Tunable High-Performance Microwave Absorption of an Ultralight and Highly Compressible Graphene Foam. \u003cem\u003eAdv. Mater.\u003c/em\u003e \u003cb\u003e27\u003c/b\u003e, 2049\u0026ndash;2053 (2015).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhao, J. P., Ren, W. C. \u0026amp; Cheng, H. M. Graphene Sponge for Efficient and Repeatable Adsorption and Desorption of Water Contaminations. \u003cem\u003eJ. Mater. Chem.\u003c/em\u003e \u003cb\u003e22\u003c/b\u003e, 20197\u0026ndash;20202 (2012).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKou, L. et al. Wet-Spun, Porous, Orientational Graphene Hydrogel Films for High-Performance Supercapacitor Electrodes. \u003cem\u003eNanoscale\u003c/em\u003e \u003cb\u003e7\u003c/b\u003e, 4080\u0026ndash;4087 (2015).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhao, X., Yao, W., Gao, W., Chen, H. \u0026amp; Gao Wet-Spun, C. Superelastic Graphene Aerogel Millispheres with Group Effect. \u003cem\u003eAdv. Mater.\u003c/em\u003e \u003cb\u003e29\u003c/b\u003e, 1701482 (2017).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLuan, V. H. et al. Synthesis of a Highly Conductive and Large Surface Area Graphene Oxide Hydrogel and Its Use in a Supercapacitor. \u003cem\u003eJ. Mater. Chem.\u003c/em\u003e (2013). 1 A 208\u0026thinsp;\u0026ndash;\u0026thinsp;211.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePeng, Z., Lin, J., Ye, R., Samuel, E. L. \u0026amp; Tour, J. M. Flexible and Stackable Laser-Induced Graphene Supercapacitors. \u003cem\u003eACS Appl. Mater. Interfaces\u003c/em\u003e. \u003cb\u003e7\u003c/b\u003e, 3414\u0026ndash;3419 (2015).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSenyuk, B. et al. Three-dimensional patterning of solid microstructures through laser reduction of colloidal graphene oxide in liquid-crystalline dispersions. \u003cem\u003eNat. Commun.\u003c/em\u003e \u003cb\u003e6\u003c/b\u003e, 7157. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/ncomms8157\u003c/span\u003e\u003cspan address=\"10.1038/ncomms8157\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2015).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFu, K. et al. Graphene Oxide-Based Electrode Inks for 3D-Printed Lithium-Ion Batteries. \u003cem\u003eAdv. Mater.\u003c/em\u003e \u003cb\u003e28\u003c/b\u003e, 2587\u0026ndash;2594 (2016).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFu, K. et al. Graphene Oxide-Based Electrode Inks for 3D-Printed Lithium-Ion Batteries. \u003cem\u003eAdv. Mater.\u003c/em\u003e \u003cb\u003e28\u003c/b\u003e, 2587\u0026ndash;2594 (2016).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhao, Z., Lin, C. Y., Tang, J. \u0026amp; Xia, Z. Catalytic Mechanism and Design Principles for Heteroatom-Doped Graphene Catalysts in Dye-Sensitized Solar Cells. \u003cem\u003eNano Energy\u003c/em\u003e. \u003cb\u003e49\u003c/b\u003e, 193\u0026ndash;199 (2018).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWang, R., Lu, K. Q., Zhang, F., Tang, Z. R. \u0026amp; Xu, Y. J. 3D Carbon Quantum Dots/Graphene Aerogel as a Metal-Free Catalyst for Enhanced Photosensitization Efficiency. Appl. Catal. 233B, 11\u0026thinsp;\u0026ndash;\u0026thinsp;18 (2018).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRamadoss, A. et al. Fully Flexible, Lightweight Performance All-Solid- State Supercapacitor Based on 3-Dimensional-Graphene/Graphite-Paper. \u003cem\u003eJ. Power Sources\u003c/em\u003e. \u003cb\u003e337\u003c/b\u003e, 159\u0026ndash;165 (2017).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePolitou, M. et al. Transition Metal Contacts to Graphene. \u003cem\u003eAppl. Phys. Lett.\u003c/em\u003e \u003cb\u003e107\u003c/b\u003e, 153104 (2015).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHe, Q., Wu, S., Yin, Z. \u0026amp; Zhang, H. \u003cem\u003eGraphene-Based Electron. Sens. Chem. Sci.\u003c/em\u003e \u003cb\u003e3\u003c/b\u003e, 1764\u0026ndash;1772 (2012).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAtaca, C., Akt\u0026uuml;rk, E., Ciraci, S. \u0026amp; Ustunel, H. High-Capacity Hydrogen Storage by Metallized Graphene. \u003cem\u003eAppl. Phys. Lett.\u003c/em\u003e \u003cb\u003e93\u003c/b\u003e, 043123 (2008).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePark, H. \u0026amp; Park, J. M. Electrophoretic deposition of graphene oxide on mild carbon steel for anti-corrosion application. \u003cem\u003eSurf. Coat. Technol.\u003c/em\u003e \u003cb\u003e254\u003c/b\u003e, 167\u0026ndash;174 (2014).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBerman, D., Erdemir, A. \u0026amp; Sumant, A. V. Few layer graphene to reduce wear and friction on sliding steel surfaces. \u003cem\u003eCarbon\u003c/em\u003e \u003cb\u003e54\u003c/b\u003e (0), 454e459 (2013).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSnook, I. \u0026amp; Barnard, A. Theory, experiment and applications of graphene nano-flakes. \u003cem\u003eJ. Nanosci. Lett.\u003c/em\u003e \u003cb\u003e1\u003c/b\u003e, 50\u0026ndash;60 (2011).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKhomyakov, P. A. et al. First-Principles Study of the Interaction and Charge Transfer Between Graphene and Metals. \u003cem\u003ePhys. Rev. B: Condens. Matter Mater. Phys.\u003c/em\u003e \u003cb\u003e79\u003c/b\u003e, 195425 (2009).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWang, Q., Pang, R. \u0026amp; Shi, X. Molecular Precursor Induced Surface Reconstruction at Graphene/Pt(111) Interfaces. J. Phys. Chem. 119C, 22534\u0026thinsp;\u0026ndash;\u0026thinsp;22541 (2015).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBiswas, R. K., McGlynn, P., O'Connor, G. M. \u0026amp; Scully, P. and and Plasma enhanced planar crystal growth of laser induced graphene. \u003cem\u003eMater. Lett.\u003c/em\u003e \u003cb\u003e343\u003c/b\u003e (2023).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eConrad, H. Electroplasticity in metals and ceramics. \u003cem\u003eMater. Sci. Eng. 287 A\u003c/em\u003e 276\u0026ndash;287 (2000).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eXie, H. et al. \u003cem\u003eJ. Mater. Sci. Eng.\u003c/em\u003e \u003cb\u003e637A\u003c/b\u003e, 23\u0026ndash;28 (2015).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eQin, R. S. \u0026amp; Su, S. X. Thermodynamics of crack healing under electropulsing. \u003cem\u003eJ. Mater. Res.\u003c/em\u003e \u003cb\u003e17\u003c/b\u003e, 2048\u0026ndash;2052 (2002).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRahnama, A. \u0026amp; Qin, R. S. Electropulse-induced microstructural evolution in a 0.14% ferritic-pearlitic steel. \u003cem\u003eScripta Mater.\u003c/em\u003e \u003cb\u003e96\u003c/b\u003e, 17\u0026ndash;20 (2015).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi, D., Yu, E. \u0026amp; Liu, Z. Microscopic mechanism and numerical calculation of electroplastic effect on metal's flow stress. \u003cem\u003eMater. Sci. Eng.\u003c/em\u003e \u003cb\u003e580A\u003c/b\u003e, 410\u0026ndash;413 (2013).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGeim, A. K. \u0026amp; Novoselov, K. S. \u003cem\u003eNat. Mater.\u003c/em\u003e \u003cb\u003e6\u003c/b\u003e, 183 (2007).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZimniak, Z. Influence of high density electric currents pulses on plastic deformation. \u003cem\u003eSteel Res. Int.\u003c/em\u003e \u003cb\u003e81\u003c/b\u003e, 729\u0026ndash;732 (2010).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePearson, W. B. Tabulated Lattice Spacings and Data of Borides, Carbides, Hydrides, Nitrides, and Binary Oxides. In A Handbook of Lattice Spacings and Structures of Metals and Alloys; Elsevier: Amsterdam, The Netherlands, 218\u0026ndash;246, (1958).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eQUASES-IMFP-TPP2M Ver. 3.0 Inelastic electron mean free paths calculated from the TPP-2M formula; \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e\u003c/span\u003e\u003cspan address=\"http://www.quases.com\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eVincent Crist, B. Handbooks of Monochromatic XPS Spectra, v.1, The Elements and Native Oxides, XPS International, LLC, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e\u003c/span\u003e\u003cspan address=\"http://www.xpsdata.com\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGrinter, D. C. et al. Adsorption and activation of CO2 on Pt/CeOx/TiO2(110): Role of the Pt-CeOx interface. \u003cem\u003eSurf. Sci.\u003c/em\u003e \u003cb\u003e710\u003c/b\u003e, 121852. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.susc.2021.121852\u003c/span\u003e\u003cspan address=\"10.1016/j.susc.2021.121852\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2021).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eQUASES-Tougaard. Software for Quantitative XPS/AES of Surface Nano-structures. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e\u003c/span\u003e\u003cspan address=\"http://www.quases.com\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWagner, C. D. et al. Standard Reference Database 20, Version 3.4 (web version) (2003). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp:/srdata.nist.gov/xps/)\u003c/span\u003e\u003cspan address=\"http://srdata.nist.gov/xps/)\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBiesinger, M. C., Lau, L. W. M., Gerson, A. \u0026amp; Smart, R. S. C. Resolving Surface Chemical States in XPS Analysis of First Row Transition Metals, Oxides and Hydroxides: Sc, Ti, V, Cu and Zn. \u003cem\u003eAppl. Surf. Sci.\u003c/em\u003e \u003cb\u003e257\u003c/b\u003e, 887\u0026ndash;898 (2010).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBiesinger, M. C. Accessing the robustness of adventitious carbon for charge referencing (correction) purposes in XPS analysis: Insights from a multi-user facility data review. \u003cem\u003eAppl. Surf. Sci.\u003c/em\u003e \u003cb\u003e597\u003c/b\u003e, 153681. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.apsusc.2022.153681\u003c/span\u003e\u003cspan address=\"10.1016/j.apsusc.2022.153681\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2022).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePimenta, M. A., Dresselhaus, G., Dresselhaus, M. S., Cancado, L. G. \u0026amp; Jorioa, Saito, A. R. Studying disorder in graphite-based systems by Raman spectroscopy. \u003cem\u003ePhys. Chem. Chem. Phys.\u003c/em\u003e \u003cb\u003e9\u003c/b\u003e, 1276\u0026ndash;1291 (2007).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eStankovich, S. et al. Synthesis of graphene-based nanosheets via chemical reduction of exfoliated graphite oxide. \u003cem\u003eCarbon\u003c/em\u003e \u003cb\u003e45\u003c/b\u003e, 1558\u0026ndash;1565 (2007).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFerrari, A. C. Raman spectroscopy of graphene and graphite: Disorder, electron\u0026ndash;phonon coupling, doping and nonadiabatic effects. \u003cem\u003eSolid State Commun.\u003c/em\u003e \u003cb\u003e143\u003c/b\u003e, 47\u0026ndash;57 (2007).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKhan, Q. A., Shaur, A., Khan, T. A., Joya, Y. F. \u0026amp; Awan, M. S. Characterization of reduced graphene oxide produced through a modified Hoffman method. \u003cem\u003eCogent Chem.\u003c/em\u003e \u003cb\u003e3\u003c/b\u003e, 1298980 (2017).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMalard, L. M., Pimenta, M. A., Dresselhaus, G. \u0026amp; Dresselhaus, M. S. Raman spectroscopy in Graphene. \u003cem\u003ePhys. Rep.\u003c/em\u003e \u003cb\u003e473\u003c/b\u003e, 51\u0026ndash;87 (2009).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDovbeshko, G. et al. Raman modes and mapping of graphene nanoparticles on Si and photonic crystal substrates. \u003cem\u003eOpt. Materials: X\u003c/em\u003e. \u003cb\u003e15\u003c/b\u003e, 100163. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.omx.2022.100163\u003c/span\u003e\u003cspan address=\"10.1016/j.omx.2022.100163\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2022).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePark, J. H. \u0026amp; Park, J. M. Electrophoretic deposition of graphene oxide on mild carbon steel for anti-corrosion application. \u003cem\u003eSurf. Coat. Technol.\u003c/em\u003e \u003cb\u003e254\u003c/b\u003e, 167\u0026ndash;174 (2014).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhang, Y., Hao, H. \u0026amp; Wang, L. Effect of morphology and defect density on electron transfer ofelectrochemically reduced graphene oxide. \u003cem\u003eAppl. Surf. Sci.\u003c/em\u003e \u003cb\u003e390\u003c/b\u003e, 385\u0026ndash;392. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://dx.doi.org/10.1016/j.apsusc.2016.08.127\u003c/span\u003e\u003cspan address=\"10.1016/j.apsusc.2016.08.127\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2016).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHafiza, S. M. et al. A practical carbon dioxide gas sensor using room-temperaturehydrogen plasma reduced graphene oxide. \u003cem\u003eSens. Actuators\u003c/em\u003e. \u003cb\u003e193B\u003c/b\u003e, 692\u0026ndash;700 (2014).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFischer-Cripps, A. C. \u0026amp; Nanoindentation Springer. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.springer.com/gp/book/9780387220451\u003c/span\u003e\u003cspan address=\"https://www.springer.com/gp/book/9780387220451\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOliver, W. C. \u0026amp; Pharr, G. M. An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments. \u003cem\u003eJ. Mater. Res.\u003c/em\u003e \u003cb\u003e7\u003c/b\u003e (6), 1564\u0026ndash;1583 (1992).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBobko, C. \u0026amp; Ulm, F. J. The nano-mechanical morphology of shale. \u003cem\u003eMech. Mater.\u003c/em\u003e \u003cb\u003e40\u003c/b\u003e (4), 318\u0026ndash;337 (2008).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eConstantinides, G., Ulm, F. J. \u0026amp; Vliet, K. V. On the use of nanoindentation for cementitious materials. \u003cem\u003eMater. Struct.\u003c/em\u003e \u003cb\u003e36\u003c/b\u003e (3), 191\u0026ndash;196 (2003).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHuo, Z. et al. Nanoindentation of circular multilayer graphene allotropes. \u003cem\u003eSci. China Technol. Sci.\u003c/em\u003e \u003cb\u003e62\u003c/b\u003e, 269\u0026ndash;275 (2019).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLee, C., Wei, X., Kysar, J. W. \u0026amp; Hone, J. Measurement of the Elastic Properties and Intrinsic Strength of Monolayer Graphene.. \u003cem\u003eScience\u003c/em\u003e. \u003cb\u003e321\u003c/b\u003e (5887), 385\u0026ndash;388 (2008).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBudynas, R. G. \u0026amp; Nisbett, J. K. \u003cem\u003eShigley's mechanical engineering design ()\u003c/em\u003eVol. 9pp. 409\u0026ndash;473 (McGraw-Hill, 2011).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhang, B. X., Hou, Z. L., Yan, W., Zhao, Q. L. \u0026amp; Zhan, K. T. Multi-dimensional flexible reduced graphene oxide/polymer sponges for multiple forms of strain sensors. \u003cem\u003eCarbon\u003c/em\u003e \u003cb\u003e25\u003c/b\u003e, 199\u0026ndash;206 (2017).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSibilia, S. et al. G. and \u003cem\u003eTemperature-dependent Electr. resistivity macroscopic graphene nanoplatelet strips Nanatechnol.\u003c/em\u003e \u003cb\u003e32\u003c/b\u003e, 275701 (2021).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBenameur, M. et al. Electromechanical oscillations in bilayer graphene. \u003cem\u003eNat. Commun.\u003c/em\u003e \u003cb\u003e6\u003c/b\u003e, 8582 (2015).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eStobinski, L. et al. \u003cem\u003eJ. Electron Spectrosc. Relat. Phenom.\u003c/em\u003e \u003cb\u003e195\u003c/b\u003e, 145\u0026ndash;154 (2014).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTougaard, S. \u0026amp; QUASES\u0026trade; Version 4.4, Software for Quantitative XPS/AES of Surface Nano\u0026thinsp;\u0026ndash;\u0026thinsp;structures by Analysis of the Peak Shape, Background (2000).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-7741311/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7741311/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eBoth graphene, a single-atom-thick layer, and its derivative, reduced graphene oxide (rGO), are highly promising materials with a wide range of applications due to their exceptional mechanical, electrical, and thermal properties. However, the application of graphene in its natural form in engineering practice is challenging, which is why a three-dimensional structure is preferred. Additionally, a very strong bond with the metal substrate is highly desirable. Here, we present a method for obtaining such micrometer-thick 3D rGO coatings on various metal alloys. This bulk material coating inherits, to some extent, the exceptional properties of single-layer graphene. The method for obtaining 3D rGO is based on the preliminary preparation of the metal surface using an argon cold plasma and the application of rGO using a pulsed electric current. A good bond between the layer and the substrate has been demonstrated, confirmed both by TEM, where no porosity was found, and in a number of other studies, including XPS, nanoindentation, and scratch testing. To better determine the quality of the obtained bond with the substrate, a resistance measurement method was used during tensile-compression tests. The 3D rGO coating developed can be used in many practical engineering applications where the high strength or other remarkable properties of graphene are particularly desirable.\u003c/p\u003e","manuscriptTitle":"Three-dimensional bulk reduced graphene oxide coatings with strong metal adhesion via cold plasma and pulsed current","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-28 16:46:03","doi":"10.21203/rs.3.rs-7741311/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-10-30T05:19:12+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-25T07:28:39+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-25T07:24:53+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"203524370182078740217123206707429517590","date":"2025-10-16T13:23:59+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"114564682730034623753597164691355046854","date":"2025-10-16T06:56:40+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"228280890760738640533840511719562729321","date":"2025-10-16T02:55:53+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-14T10:19:32+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-13T13:29:40+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-10-13T12:49:55+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-08T10:39:22+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-10-08T10:34:27+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"51fa08d1-f88e-41e0-97c4-98f225725509","owner":[],"postedDate":"October 28th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":56857303,"name":"Physical sciences/Engineering"},{"id":56857304,"name":"Physical sciences/Materials science"},{"id":56857305,"name":"Physical sciences/Nanoscience and technology"}],"tags":[],"updatedAt":"2026-02-02T16:03:44+00:00","versionOfRecord":{"articleIdentity":"rs-7741311","link":"https://doi.org/10.1038/s41598-026-37227-1","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2026-01-29 15:58:35","publishedOnDateReadable":"January 29th, 2026"},"versionCreatedAt":"2025-10-28 16:46:03","video":"","vorDoi":"10.1038/s41598-026-37227-1","vorDoiUrl":"https://doi.org/10.1038/s41598-026-37227-1","workflowStages":[]},"version":"v1","identity":"rs-7741311","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7741311","identity":"rs-7741311","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}