Hybrid MXene Coatings: Unlocking Synergistic Lubrication Properties of Ti₃C₂Tₓ and Nb2CTx MXenes for Improved Tribological Performance

Hybrid MXene Coatings: Unlocking Synergistic Lubrication Properties of Ti₃C₂Tₓ and Nb2CTx MXenes for Improved Tribological Performance | 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 Hybrid MXene Coatings: Unlocking Synergistic Lubrication Properties of Ti₃C₂Tₓ and Nb 2 CT x MXenes for Improved Tribological Performance Christina Danecker, Sabine Schwarz, Marko Piljevic, Jakob Rath, and 7 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7574829/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 22 Dec, 2025 Read the published version in Scientific Reports → Version 1 posted 11 You are reading this latest preprint version Abstract The development of advanced solid lubricants is critical for enhancing energy efficiency and durability in mechanical systems. In this study, we investigate the tribological performance of hybrid solid lubricant coatings composed of two-dimensional titanium carbide (Ti₃C₂Tₓ)- and niobium carbide (Nb₂CTₓ)-based MXenes. Coatings were applied via spray deposition onto AISI 304 stainless steel substrates and tested under dry sliding conditions against Al₂O₃ counterbodies. While individual MXene coatings exhibited limited friction stability, the hybrid Ti₃C₂Tₓ/Nb₂CTₓ coating demonstrated a significantly reduced and stable coefficient of friction (COF < 0.2) throughout the test duration. Comprehensive surface and structural analyses of the wear tracks including SEM-EDS, Raman spectroscopy, and TEM revealed the formation of a compact, stratified tribofilm. We propose as a phenomenological model that under tribological stress, the hybrid system undergoes adaptive reconfiguration: Ti₃C₂Tₓ anchors to the substrate, enhancing adhesion and mechanical integrity, while Nb₂CTₓ migrates to the sliding interface, acting as a sacrificial layer. This dynamic redistribution results in a synergistic interaction that enhances tribochemical resilience and wear resistance. These findings establish hybrid MXene coatings as a promising strategy for engineering next-generation solid lubricants, offering new pathways for the design of high-performance, energy-efficient coatings in demanding industrial applications. Physical sciences/Engineering Physical sciences/Materials science Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction The transition to sustainable energy production and transportation is essential for reducing emissions and addressing climate change. Securing energy efficiency is equally important in the endeavour of achieving sustainability goals. The International Energy Agency (IEA) highlights that about 30% of cumulative CO₂ emission reductions can be achieved by promoting energy efficiency in technologies and the adoption of less energy-intensive materials and processes [ 1 ]. Tribology, the science of friction, wear and lubrication, plays a crucial role in enhancing the efficiency, reliability, and lifespan of mechanical systems. Indeed, tribological losses are responsible of approximately 23% of global energy consumption. Therefore, with almost all industry sectors depending on machines with moving components, reducing friction-related losses is fundamental to improving overall performances [ 2 ]. As friction and wear lead to considerable material and energy losses in mechanical systems [ 3 ], the simplest and most efficient solution is the application of a lubricant to separate the interacting surfaces [ 4 ]. Depending on the application and environmental conditions, various lubricants are used to reduce friction and wear, such as mineral- or synthetic oils [ 5 ], greases [ 6 ], ionic liquids [ 7 ], and solid lubricants [ 8 ]. However, as technological and industrial needs become more demanding for high performances in complex scenarios (e.g., aerospace), the scientific research is stirred toward evaluating the tribological performances of novel advanced materials. Among these, two-dimensional (2D) materials with layered structures have emerged as a highly researched class of solid lubricants, due to their exceptional mechanical, physical, chemical, and tribological properties [ 9 ], [ 10 ], [ 11 ]. 2D materials are thin, sheet-like structures that consist of one or a few atomic layers in thickness [ 11 ]. These layered materials can form easy-to-shear tribolayers, which separate sliding surfaces and help reduce friction and wear [ 12 ]. The functionality of 2D materials is based on weak van der Waals interactions between the layers, enabling them to slide under low shear forces. At the same time, strong in-plane covalent bonds hold the atoms together, allowing the layers to move easily without separating completely [ 13 ]. MXenes, 2D transition metal carbides, nitrides, and carbonitrides, have recently received considerable attention [ 14 ]. They are produced by removing the A-group layer atoms (e.g. Al) from M n+1 AX n or MAX phases [ 15 ]. After removing the A group elements, multilayered MXenes remain, described by the chemical formula M n+1 X n T x (n = 1 to 4). The surface is terminated with functional groups such as -O, -OH, -F and/or -Cl, collectively represented as 'Tₓ', depending on the specific etching route used (HF, MILD method, Electrochemistry or Molten Salt) [ 4 ], [ 14 ], [ 16 ], [ 17 ]. MXenes demonstrate application potential in several fields, such as energy storage [ 18 ], [ 19 ], catalysis [ 19 ] biomedical applications for biosensors [ 20 ] or drug delivery [ 21 ], [ 22 ]. One of the most well-known and extensively studied MXene is titanium carbide (Ti₃C₂Tₓ), produced by selective etching of Ti₃AlC₂. Its properties include high electrical conductivity [ 23 ], biocompatibility [ 24 ], antibacterial activity [ 25 ] and good mechanical characteristics such as tensile strength, elastic modulus, and fracture strain [ 26 ]. Due to their chemical and structural versatility combined with their easy-to-shear ability and strong interfacial bonding, Ti 3 C 2 T x have emerged as a promising material for tribological applications [ 27 ], [ 28 ], including their use as lubricant additives [ 29 ], [ 30 ] and solid lubricant coatings [ 31 ], [ 32 ]. Another notable member of the MXene family is niobium carbide (Nb 2 CT x ) [ 33 ]. Nb 2 CT x has been used in various energy applications due to its exceptional electrical conductivity, outstanding chemical stability and high electronic conductivity [ 34 ]. These applications include supercapacitors [ 35 ], rechargeable batteries [ 33 ], sensors [ 36 ], and even biomedical uses [ 37 ]. Beyond energy-related applications, recent studies have also explored the tribological potential of Nb based MXenes. By using Atomic Force Microscopy (AFM), it was observed that Nb 2 CT x MXenes exhibited lower friction and adhesion forces compared to Ti 3 C 2 T x , with both properties decreasing as the temperature increased [ 38 ]. The different behaviours in friction and adhesion were attributed to differences in surface dipole moment density, with Nb 2 CT x having a denser surface compared to Ti 3 C 2 T x [ 38 ]. Nb 2 C nanosheets with varying degrees of oxidation were applied as solid lubricant additives in water-based lubrication systems [ 39 ]. The results showed that a medium oxidation degree significantly reduced the coefficient of friction by 90.3% and the wear rate by 73.1% compared to pure water, demonstrating the added value of Nb 2 C [ 39 ]. These exceptional tribological characteristics of MXenes (Ti 3 C 2 T x and Nb 2 CT x alike) are strongly influenced by factors such as the number of nanosheets, the orientation of individual monolayers, the lateral flake size, the film thickness, the interlayer interactions, the substrate interaction, and surface terminations [ 8 ], [ 26 ] [ 40 ]. The latter, directly affect the adhesion of both the individual layer and at the interface with the substrate, as presented in a recent density functional theory (DFT) study taking iron and iron oxide as substrates [ 41 ]. DFT suggests that tuning the density of -OH and -F terminations may lead to a significant improvement in the friction and wear behaviour of MXenes [ 41 ], as proven in our recent work on the tribological performances of electrochemically synthesized MXenes [ 42 ]. The oxidation properties of MXenes in air, liquid, and solid environments reveals their strong susceptibility to degradation as a key challenge. For instance, Ti 3 C 2 T x flakes in liquids is prone to form TiO 2 , which reduces conductivity and limits long-term stability [ 43 ]. Similarly, at 20% relative humidity, the coefficient of friction of Ti 3 C 2 T x remains stable for about 4000 sliding cycles, whereas at higher humidity levels (approximately 80%), a significant rise in the coefficient of friction is observed [ 44 ]. Novel strategies are required to overcome specific challenges in MXene tribology such as oxidation stability and tribochemical resilience. The exploration of MXene hybrids is gathering interest owing to the possibility of igniting synergistic effects that may overcome limits of the singular species. For instance, a recent study has shown the ability to tailor the optical properties of Ti₃C₂Tₓ and Nb 2 CT x hybrids [ 45 ]. Similarly, Ti₃C₂Tₓ combined to MoS 2 has demonstrated great tribological performances, with a coefficient of friction as low as 0.14 and a wear rate of 0.49 x 10 − 5 mm³/Nm [ 46 ]. Inspired by these works, hereby we investigate the synergistic effect of combining Ti₃C₂Tₓ and Nb 2 CT x to form hybrids with advanced tribological performances. Specifically, we evaluate the tribological performance of a spray coated Nb₂CTₓ /Ti₃C₂Tₓ hybrid deposited onto AISI 304 steel substrates, which are then tested under linear sliding conditions against a Al 2 O 3 counterbody. Uncoated AISI 304 steel substrates, Ti₃C₂Tₓ, and Nb 2 CT x coatings were used as reference materials. Detailed post-experimental analysis of the coatings and the corresponding wear tracks provides insight into the underlying mechanisms of the observed tribological behaviour. The hybrid coating exhibited a stable coefficient of friction (COF) below 0.2, demonstrating excellent lubricity. This is attributed to the tribo-induced formation of a compact, patchy tribofilm, which effectively reduces the COF and protects the substrate from wear. Surface analysis of the wear tracks was conducted to investigate the underlying tribochemical processes, using techniques such as Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). In conclusion, we demonstrate that the Nb₂CTₓ/Ti₃C₂Tₓ hybrid coating provides superior tribological performance due to the synergistic interaction between the two MXene species. Under sliding conditions, Nb₂CTₓ and Ti₃C₂Tₓ undergo adaptive reconfiguration aimed at minimizing the COF. Nb₂CTₓ becomes more exposed to the sliding interface, acting as a sacrificial layer that undergoes oxidation, while Ti₃C₂Tₓ preferentially positions itself at the interface with the substrate, enhancing adhesion and contributing to the mechanical robustness of the tribofilm. This dynamic redistribution underscores the complementary roles of the two MXenes in forming a stable, low friction tribolayer. Our findings present a novel strategy for engineering MXene-based solid lubricant hybrid composites; wherein two-dimensional materials are designed to exhibit enhanced functional behaviour. This methodology leverages the vast compositional diversity of the MXene family and aligns with the growing interest in high-entropy systems. As such, it opens new avenues for both fundamental research in advanced materials and the development of innovative, application-driven solutions for industry. Materials and Methods Synthesis of Ti 3 AlC 2 and Nb 2 AlC MAX phases Elemental powders of titanium (Ti, -325 mesh, 99%, Thermo Scientific), aluminum (Al, -325 mesh, 99.5%, Thermo Scientific), and graphite (C, 7–11 µm, 99%, Alfa Aesar) were combined in a Ti:Al:C molar ratio of 3.00:1.20:1.88. The mixture was placed in a high-density polyethylene (HDPE) container along with ten 10 mm yttria-stabilized zirconia (YSZ) balls and mixed using a Turbula T2F mixer at 56 rpm for 3 h. It was then transferred to an alumina crucible and heated in a tube furnace under a continuous argon flow (0.2 L/min). The temperature was increased to 1600°C at a rate of 5°C/min and held for 2 h. After the reaction, the system was allowed to cool naturally to room temperature under inert atmosphere. The resulting lightly sintered Ti 3 AlC 2 brick was ground and sieved to obtain powders smaller than 45 µm. Synthesis of Nb 2 AlC MAX phase followed the same procedure however using elemental powders of niobium, aluminium, and graphite with molar ratios Nb:Al:C of 2.00:1.30:0.95C. After mixing, the mixture was pressed into green pellets 12–13 g/pellet. The pellets were sintered at 1600°C and held for 4 h. Synthesis of Ti 3 C 2 T x and Nb 2 C x MXene phases Ti 3 C 2 T x was obtained by selectively etching the aluminum layers from Ti₃AlC₂ using an in-situ HF-generating etchant composed of potassium fluoride (KF, 99%, Thermo Scientific) and hydrochloric acid (HCl, 9 M, Fisher Chemicals). The etching solution was prepared by mixing 20 mL of 9 M HCl per gram of Ti 3 AlC 2 with KF at a molar ratio of 9:1 (KF:Ti₃AlC₂). Ti₃AlC₂ powder was gradually added to the etchant under magnetic stirring at 500 rpm and maintained at 45°C for 48 hours. Following etching, the product was soaked in 9 M HCl for 18 hours to remove excess salts. The resulting powder was then washed by distributing it into 50 mL centrifuge tubes, using one tube per 0.5 g of precursor. Deionized (DI) water was added, followed by centrifugation at 3500 rpm for 2 minutes. The supernatant was discarded, fresh DI water was added, and the sediment was redispersed using a vortex mixer. This process was repeated until the pH of the supernatant exceeded 6. Nb 2 C x was produced by inserting Nb 2 AlC powders into hydroflouric acid (HF, 48–51%, Alfa Aesar) with a ratio of 1 g: 20 ml the sample was stirred at 40°C for 5 days. The washing and filtering steps were similar to that of Ti 3 C 2 T x . The morphology of the as-synthesised Ti₃C₂Tₓ and Nb 2 CT x MXenes was characterised by scanning electron microscopy (SEM, FEI Quanta 250 FEG) operated at an acceleration voltage of 5 kV. Secondary electron imaging was performed using an Everhart-Thornley detector (ETD). In addition, TEM (Tecnai F20) was performed at 200 kV acceleration voltage for higher-resolution imaging. In addition, X-ray diffraction (XRD) and Raman spectroscopy were performed on both MXene powders to gain further information about their surface terminations. XRD were carried out using a Malvern Panalytical X’Pert MPDII equipped with a X’Celerator semiconductor detector. Diffraction patterns were recorded over a 2θ range of 5° to 70°, with a total scan duration of 20 min. A LabRam Aramis Raman microscope (Horiba Jovin Yvon, Germany) is used to record Raman spectra of Ti 3 C 2 T x and Nb 2 CT x MXene powder. Red raman laser with wavelength of 632 nm and laser power of 2 mW is used to excite samples. Spectra were recorded from 100 to 2000 cm − 1 with a 1200 mm − 1 grid. Both powders are tested separately before applying on substrate. Data are evaluated in OriginPro 2023b software, where background is removed and peaks are normalized. Coating deposition Overall, four different samples were tested: one uncoated reference and three distinct coating systems — a pure Ti₃C₂Tₓ coating, a Nb 2 CT x coating, and a hybrid coating composed of a combination of both MXenes. For the hybrid coating Nb 2 CT x were first applied, followed by the same amount of Ti 3 C 2 T x , ensuring a uniform mixture of both materials. These coatings were applied to mirror-polished stainless-steel platelets (AISI 304) with dimensions of 15 x 15 x 2 mm³, a Young’s modulus of 200 GPa, a Poisson´s ratio of 0.29, and an initial roughness S q of about 0.18 µm. The solid lubricant coatings were deposited onto these substrates by using the airbrush spray-coating process. Uncoated plates and balls were also tested as reference materials. All MXenes were dispersed separately in ethanol at a concentration of 2 mg/mL, regardless of the composition (Table 1 ). Table 1 Overview of the deposited coatings, including their design, thickness and applied volume. Name Material / Coating Spray volume (mL) Thickness tribofilm (nm) reference AISI 304 - - Ti 3 C 2 T x MXene Ti 3 C 2 T x 4 1383.2 ± 142 Nb 2 CT x MXene Nb 2 CT x 4 202.1 ± 56 Hybrid Combination of Nb 2 CT x + Ti 3 C 2 T x 4 (2 + 2) 230.5 ± 82 The following steps were taken to prepare the dispersion. The dispersions were first homogenised using a shear mixer (T 25 basic IKA® ULTRA-TURRAX®) for 5 minutes at 11000 rpm. To improve the dispersion and distribution of the nanosheets, tip sonication (QSONICA CL-18 Sonicators) was applied for 1 h (5 s on, 5 s off, 50 W power), followed by 2 h of bath sonication. Directly afterwards, 4 mL of the dispersion was transferred via a syringe into a self-build spray coating set-up. The distance between nozzle and steel substrate was maintained at 10 cm, and the air pressure during spray-coating at 1,5 bar. To ensure rapid solvent evaporation, prevent droplet formation, and achieve uniform coatings the substrates were pre-heated and placed on a heating plate set to 80°C during deposition. To fabricate the hybrid coating, 2 mL of each MXene dispersion were sprayed onto the substrate, starting with Nb₂CT x followed by Ti₃C₂Tₓ, resulting in a total spray volume of 4 mL. To prevent cross-contamination and ensure material purity, two identical airbrushes of the same model were used - one for each dispersion. Tribological experiments The tribological performance of the different solid lubricant coatings were evaluated using a ball-on-disc tribometer (Rtec Instruments, MFT-2000A) in linear sliding mode. The counterbody material was Al 2 O 3 with a diameter of 6 mm. The linear sliding velocity was set to 1 mm/s, stroke length to 1 mm, the normal force to 0.25 N with a calculated hertzian contact pressure of 0.48 GPa, which is in the operating range of many machine elements such as journal bearings, and the test duration to 30 min. A case of moderate contact stresses is reflected in the initial contact pressure at the contact centre. The tests were carried out at room temperature between 20.2°C and 23.5°C and the relative humidity ranged between 20.5% and 25%. All experiments were performed three times to ensure reproducibility and statistical significance, as well as to calculate the mean values and error bars. Surface characterization of the wear track Before and after tribological experiments, all samples were analysed by confocal laser scanning microscopy (CLSM, Keyence VK-X1100). Surface morphology and wear tracks were analysed using a SEM equipped with an ETD detector. Imaging was carried out in conjunction with the preparation of cross sections and TEM lamellae prepared using a ThermoFisher Scios II dual beam system. Surface sensitive chemical characterisation was carried out using X-ray photoelectron spectroscopy (XPS, PHI Versa Probe III-spectrometer) equipped with a monochromatic Al-Kα X-ray source and a hemispherical analyser (acceptance angle: ±20°). Pass energies of 140 eV and 27 eV and step widths of 0.5 eV and 0.05 eV were used for survey and detail spectra, respectively. (Excitation energy: 1486.6 eV Beam energy and spot size: 2 W onto 100 µm; Mean electron takeoff angle: 45° to sample surface normal; Base pressure: 5x10 − 10 mbar, Pressure during measurements: <1 x 10 − 8 mbar). Samples were mounted on non-conductive tape. A combination of electronic and ionic charge compensation was used for all measurements (automatized as provided by PHI). Surface cleaning was performed by using a PHI Gas Cluster Ion Gun (GCIB) (5 kV for 300 s). Spectral analysis was carried out using CasaXPS, with corrections for instrument transmission and background removal via the Shirley background [ 47 ] and sensitivity factors provided by PHI [ 48 ]. Deconvolution of spectra was carried out by using a Voigtian lineshape if not stated otherwise. All content values shown are in units of relative atomic percent (at.-%), where the detection limit in survey measurements usually lies around 0.1–1 at.- %, depending on the element. Assignment of different components was primarily done using Refs. [ 49 ], [ 50 ]. Besides the powder characterization, Raman spectroscopy was employed to characterize the coatings and wear tracks. Hybrid MXenes wear scars were recorded in three different zones: reference coating, tribolayer and pile-up zone. Both wear scars of MXenes tested separately were recorded in two zones: tribolayer and pile-up zone. Settings used during measurement were: RTD exposure time of 1 s, exposure time of 100 s and Accumulation number of 2. All examined zones were measured without filter using a 50x Fluotar objective. The wear tracks were further analysed by scanning electron microscopy (SEM, Zeiss Eco 10, equipped with a tungsten cathode as an electron source) in combination with EDS. A Zeiss SmartEDS detector (silicon drift with a silicon nitride window) was employed for EDS measurements. The excitation energy was 20 kV, and the base system pressure was 1,3 x 10 − 4 mbar and during the measurements 5 x 10 − 5 mbar. The structure of the formed tribofilms was analyzed by transmission electron microscopy (TEM, FEI TECNAI F20). Energy dispersive X-ray spectroscopy (EDS) was performed within the TEM using an EDAX-AMETEK Apollo XLTW SDD system. For TEM, a thin lamella was prepared using a ThermoFisher Scios II Focused Ion Beam (FIB). The lamella measured approximately 20 × 10 µm² with a thickness less than 100 nm thick in the regions of interest. A protective layer of tungsten is deposited to protect the coating during the cutting process. Phase analysis was performed using Selected Area Electron Diffraction (SAED) patterns. In addition, high-resolution TEM (HR-TEM) imaging was used for phase analysis using lattice spacing measurements from the HR-TEM images. Results and discussion Structure and chemical characterization of the used MXenes The Ti 3 C 2 T x used in this study was synthesized by in situ HF etching of Ti 3 AlC 2 , while Nb 2 CT x was obtained from Nb 2 AlC 2 . Figure 1 (a) and (b) show the multi-layered flake structures imaged by scanning electron microscopy (SEM). Further details on the layered structure were revealed by transmission electron microscopy (TEM). Figure 1 (c) shows a single flake of the TEM image of a Ti 3 C 2 T x revealing an interlayer spacing in the z-direction of 1.04 ± 0.29 nm and 0.92 ± 0.37 nm for Nb 2 CT x , (Figure S1 , Supporting Information), which corresponds to the values reported in literature [ 51 ]. The TEM image of a Ti 3 C 2 T x flake is shown in Fig. 1 (c). A selected area diffraction pattern was recorded of position 1 Fig. 1 (c1)) confirms a crystalline structure, which could be identified as Ti 3 C 2 in zone axis (ZA) [441]. Figure 1 (d) and a larger magnification in (d1) shows the layered structure of the material with interlayer spacing of 1.28 nm (Figure S1 (c), Supporting Information). A TEM image of a Nb 2 CT x flake is presented Fig. 1 (e), with corresponding SAED pattern of position 2, (Fig. 1 (e1), confirming the crystalline structure of Nb 2 C in ZA [001]. High resolution TEM images of the structure are shown in (f) and enlarged (f1). The phase purity and structural characteristics of the synthesized MXene powder were confirmed by powder X-ray diffraction (Figure S2 (a), Supporting Information). The diffraction pattern displayed a sharp and intense (002) peak at low angles, characteristic of well-ordered MXene layers with increased interlayer spacing, indicating successful etching and delamination of the MAX phase. The absence of residual MAX phase reflections further confirms the high purity of the final product. Figure S2 (b), Supporting Information illustrates the Raman spectra for two MXenes: Ti 3 C 2 T x (black) and Nb 2 CT x (red). The Ti-MXenes show typical peak at 207cm − 1 corresponding to an out of the plane Ti-C vibration A 1g . Peak at 374 cm − 1 indicates vibrations coming from the surface terminal groups of MXene, while peak at 626 cm − 1 indicates carbon vibrations. Two peaks D and G, coming from carbon vibrations are located at around 1380 and 1546 cm − 1 . Small peak at 160 cm − 1 indicates Ti-O bond vibration [ 17 ]. The Nb-MXene Raman spectrum shows peaks which are in good agreement with those reported in literature. The peaks at 133 and 267 cm − 1 represent in-plane and out-of-plane Nb vibrations (Nb–O), respectively. Peaks detected at 251, 435 and 639 cm − 1 represent OH, F and O surface termination vibrations, respectively. D and G carbon peaks are present at around 1363 and 1600 cm − 1 [ 52 ]. Frictional performance of MXenes The tribological performance of the different MXene coated samples was evaluated using a ball-on-disk tribometer operating in linear sliding mode. Coefficient of friction (COF) values were recorded for Ti₃C₂Tx, Nb₂CTx and their hybrid coating in contact with a Al 2 O 3 counterbody, as illustrated in Fig. 2 (a). Their frictional behaviour is compared to that of an uncoated steel reference sample, tested without any lubrication. In the case of the uncoated steel sample against the Al 2 O 3 counterbody, the typical behaviour under dry sliding conditions with a ceramic counterpart is observed, with noticeable fluctuations during the running-in phase and a rapid increase in the COF, regardless of the test conditions [ 53 ]. More specifically, the initial COF for the steel reference (steel REF), is approximately 0.25, which quickly increases to almost 0.7 within the first 400 s, after which a steady state value of around 0.8 is reached. The observed friction behaviour corresponds to the typical running-in phase of dry, uncoated metal-ceramic contact under ambient conditions. The significant increase and variability in the COF are primarily attributed to the progressive removal of microscopic surface roughness caused by abrasion and shear at the contact interface [ 54 ]. Additionally, ongoing mechanical wear and material transformation generate wear debris, which further contributes to fluctuations and variations in the COF [ 55 ]. In contrast, the Ti 3 C 2 T x coated sample held the COF to 0.2 in the first 200 seconds, to then rapidly diverge to 0.8. The evolution in time of the COF for the Nb 2 CT x coating reveals a different trend. The COF started at 0.17, followed by a gradual increase to around 0.5, where it remained stable until around 1200 seconds before further rising to 0.8. Compared to the reference and Ti 3 C 2 T x , the Nb 2 CT x coating showed a larger standard deviation, indicating greater variability in friction behaviour. A possible interpretation of the COF vs time curve suggests that under the applied tribological conditions, the contact pressure of 0.48 GPa led to the removal of the MXene coatings from the contact zone, resulting in material accumulation at the turning points of the wear track. This detachment facilitated the formation of debris and oxides, which acted as abrasives and contributed to the observed increase in COF. A significant reduction and stability in time of the COF was observed for the hybrid coating. Starting at 0.14, the friction reduction remains consistent and stable throughout the entire test duration, without noticeable fluctuations. By the end of the test, the COF stabilizes at 0.17, demonstrating that the hybrid coating retains its beneficial friction-reducing effects. The results surpass the previous tests, with the hybrid coating achieving 82% reduction in COF with respect to the references. Panels (b), (c), and (d) of Fig. 2 present the wear track morphologies after the tribological tests for Ti 3 C 2 T x , Nb 2 CT x and the hybrid coating respectively. The wear track morphology of the hybrid coating differs significantly from those of the individual MXene coatings. For the hybrid coating (Fig. 2 (d)), a tribofilm formed by dark patchy traces is observed. In contrast, the wear tracks of the individual MXene coatings (Fig. 2 (b) and (c)) show an uneven film formation, particularly at the track edges and reversal points. Surface analytics is required to clarify the underlying tribological mechanism. To this goal, we carried out various post-test analyses of the substrate surfaces after the friction test. To gain insight into the chemical and structural properties, the results of XPS, Raman, and TEM as well as TEM-EDS analysis are presented in the following sections. Since the most promising behaviour was observed on the hybrid coating, our analysis focuses primarily on this coating. Surface analysis of the wear tracks. SEM EDS analysis was carried out on different regions of the wear tracks. For the Ti 3 C 2 T x coated sample, no detectable Ti was found in the central region of the wear track (area 4, Figure S4 (a), Supporting Information), whereas a small amount of detectable Nb was identified in the corresponding region of the Nb 2 CT x coated sample (area 4, Figure S4 (b), Supporting Information). These results suggest that both Ti 3 C 2 T x and Nb 2 CT x were pushed away from the contact zone and accumulated at the edges, indicating partial coating failure due to lack of adhesion. We applied Raman spectroscopy to characterize the tribofilms found in the obtained wear tracks (see Fig. 3 ). The spectra exhibit vibrational modes corresponding to characteristic peaks of MXene powders (see Figure S2 (b), Supporting Information), indicating the chemical stability of the formed tribolayer. In contrast, the pile-up zone reveals a weak Ti-O vibrational mode, which suggests that the MXene is partially oxidised. Additionally, the D and G bands exhibit significantly higher intensity in the pile-up region than the Ti out of-the-plane vibration, indicating an increased carbonaceous contribution. The sharp peak at 659 cm − 1 may be due to intensified carbon vibrations or potential contributions from Fe 3 O 4 [ 56 ]; however, the overlap of these two signals makes it difficult to identify the individual contributions precisely. The Raman spectrum of Nb-MXene shows the same characteristic peaks as the powder sample, though with altered intensity ratios (Figure S2 (b), Supporting Information). A pronounced peak at 675 cm − 1 is observed in the tribolayer region, which corresponds to Nb-O bond vibrations. The peak intensity is more dominant than the one found in Ti 3 C 2 T x , suggesting that Nb-based MXene is more prone to oxidation with respect to the Ti counterpart. The results suggest that the tribological test has induced partial chemical instability of the Nb-MXene. In contrast, the pile-up zone exhibits spectral features consistent with those of the original powder, possibly indicating that the MXene flakes that remain in the contact area undergo harsh tribochemical processes, while those able to slide toward the pile-up zone can maintain a less oxidised state. Finally, Fig. 4 shows the Raman spectra of the hybrid coating evaluated in three points on the surface. The tribolayer (red), the pile-up zone (green), and the untested coating (black). Only Ti-based MXenes were detected in the reference zone of the hybrid coating, with no peaks corresponding to Nb-MXenes vibrations. Notably, no peaks indicating oxidation of MXene were found, suggesting good oxidation stability of the hybrid coating. The tribolayer in the hybrid MXenes indicates the presence of both types of MXene due to distinct peaks appearing at 203 and 258 cm − 1 , representing Ti and Nb vibrations, respectively. The relatively low intensity of the D and G bands indicates a reduced degree of carbon disorder within the tribolayer. Additionally, a new vibrational mode observed at 770 cm⁻¹, attributed to the A₁g(C) phonon, emerges in the Raman spectrum. Notably, this feature is absent in both the pristine MXene powders (see Figure S2 (b), Supporting Information) and the singly MXene-coated samples (Figure S3, Supporting Information), which exhibit pronounced carbon-related vibrations but lack the 770 cm⁻¹ peak. This distinction suggests that the Raman signature reflects a synergistic effect arising from the hybrid coating, surpassing the characteristics of the single-coated configurations. Specifically, the diminished D and G band contributions, coupled with the appearance of the A₁g(C) mode, imply a surface restructuring within the tribolayer. This restructuring likely results in better ordering or exposure of MXene flakes. It is proposed that the kinetic energy imparted during tribological stress facilitates this transformation by reducing carbon disorder and promoting the alignment of MXene flakes at the interface with the counterbody. Analysis of the pile-up zone reveals a weak Nb-O peak, which is also present in the reference powder. This suggests that partially oxidised Nb-MXenes are being ejected from the contact zone into the pile-up zone by the oscillatory motion of the counterbody, while unoxidised particles form a stable tribological film. X-ray photoelectron spectroscopy (XPS) was conducted on both the as-deposited coating (reference) and the wear track (tribolayer) to further examine the oxidation state of niobium. Specifically, we analysed the C 1s, F 1s, Nb 3d, O 1s, and Ti 2p core levels (see Figure S10, Supporting Information). The tribolayer exhibited a higher concentration of oxides, particularly TiO₂ and Nb₂O₅, compared to the reference surface. Quantitative analysis revealed that the oxide-to-carbide ratio for Nb 3d exceeded unity in both the reference and tribolayer regions, whereas for Ti 2p, this ratio remained below one (see Table S3, Supporting Information). These findings suggest that Nb-based MXenes are more susceptible to oxidation under tribological stress, while Ti-based MXenes retain a more carbide-like character. This trend is consistent with the Raman spectroscopy results, which also indicated a higher degree of structural preservation in the Ti-based components. Transmission electron microscopy (TEM) Analysis. To gain deeper insight into the structure and composition of the tribofilms formed in the MXene hybrid coating, transmission electron microscopy (TEM) was employed to examine the wear track. A focused ion beam (FIB) was used to extract a cross-sectional TEM lamella from the edge region of the hybrid coating, approximately at the centre of the wear track (see Figure S4, Supporting Information). The cross-sectional TEM image reveals a compact, flat tribofilm with an average thickness of approximately 230.5 ± 82 nm following tribological testing (Figure S5 (h)-(i), Supporting Information). To further investigate the elemental distribution within the tribolayer and assess compositional changes induced by sliding, energy-dispersive X-ray spectroscopy (EDS) mapping was performed. The elemental maps show a relatively uniform distribution of Ti and Nb throughout the tribofilm (Fig. 5 (a3) and Fig. 5 (a4)). Notably, the oxygen signal (Fig. 5 (a6)) closely follows the Ti distribution, consistent with the presence of oxygen-containing surface terminations on Ti-based MXenes. Interestingly, the cross-sectional analysis reveals a stratified structure within the tribofilm: Ti-rich regions are predominantly located near the substrate, while Nb-rich regions are concentrated toward the top surface. This stratification does not correspond to the original sequential deposition of the coating layers, suggesting that it results from tribologically induced redistribution during sliding. TEM was used to examine the microstructure of two distinct regions within the tribofilm (Zone 1 and Zone 2), and selected area electron diffraction (SAED) patterns were acquired for the evaluation and determination of the crystal phase after the deformation caused by the tribo-tests see Fig. 6 ). In Zone 1, TEM images (Fig. 6 (a2)) reveal that the tribofilm possesses a mixed microstructure. A TEM image with a lager magnification taken at position 1 highlights the layered structure of the MXene flakes (Fig. 6 (a4)). Figure 6 (a3) confirms nanocrystallinity, indicated by the formation from spots to rings. Further, the diffraction patterns show a spread in the radio of the diffraction spots, which is due to a slight but continuously change in the crystal lattice parameters. In contrast, the pre-tested MXene flakes shown in Fig. 1 (c1) and (e1) indicate a pure single crystal structure. Thus, it can be concluded that this change in the crystal structure is caused by the tribological tests. In Zone 1, an amorphous ring is clearly visible in the diffraction pattern. It is stemming from the left and right outer part in the selected area diffraction aperture – see Fig. 6 (a2). The amorphous regions indicate a complete destruction of the crystallinity of the Nb and Ti flakes, caused by the tribological tests. The diffraction pattern shown in Fig. 6 (b3) shows the crystalline structure of Ti 3 C 2 T x . More details are available in the Supporting Information (Figure S7 and S8). Moreover, Fig. 6 (b4), shows the area of Zone 2 at higher magnification in a high-resolution TEM image, where crystalline and amorphous regions can be identified immediately. For Nb 2 CT x and Ti 3 C 2 T x MXenes (crystal structure confirmed by mean lattice spacing distances) an area named “MX” is defined, where MXene-layers are visible but not clearly identifiable. Moreover, an amorphous region runs through the centre of the picture. Details on the calculated lattice distances are reported in Figure S9 (Supporting Information). It could not be observed any gap between the different areas, suggesting that the MXene-flakes are compacted together in different configurations after the tribological tests. The diffraction patterns could be clearly identified as the phases Nb 2 C and Ti 3 C 2 , confirming that a part of the tribofilm maintains the initial crystallinity of the unencumbered flakes. Tribological mechanism of Nb-Ti MXene hybrid coating The developed hybrid coating shows exceptional COF performances (Fig. 2 ), and the surface analytics confirm the presence of both MXenes types in the wear tracks (Fig. 4 , Fig. 5 ), where they present diverse crystallographic structures (Fig. 6 ). Interestingly, the cross-section investigation by TEM-EDS presents a different arrangement of the MXene flakes with respect to the initial application sequence: the hybrid coating is prepared by depositing first the Nb 2 CT x solution followed by the Ti 3 C 2 T x solution, creating a mixture of the two materials which could not be confirmed after the tribological test. Hereby we propose an adaptive reconfiguration as a possible tribological mechanism. Upon the onset of tribological stress, the system self-organizes into a configuration that minimizes friction and wear. Thus, Ti₃C₂Tₓ, which has a better chemical affinity to the substrate with respect to Nb₂CTₓ due to the stable Ti-Fe interfacial bonding, is displaced at the substrate interface, forming a stable and adherent layer. Consequently, the sliding interface transitions to one dominated by Nb₂CTₓ vs. Ti₃C₂Tₓ flake interactions, which lowers the COF due to interlayer shearing between the MXenes species. Notably, Raman spectroscopy indicates that the pile-up zone is predominantly composed of oxidised Nb₂CTₓ, confirming that in this adaptive configuration, Nb-based MXenes migrate to the counterbody interface and are subsequently transported out of the contact zone. However, due to the poor chemical stability of Nb₂CTₓ, it collapses to its oxidised form as showed by XPS. Both TEM and Raman spectroscopy highlight the significant role of carbon: Raman reveals distinct differences in carbon vibrational modes between the wear track and the pile-up zone (Fig. 4 ), while TEM shows amorphous regions (Fig. 6 ) and TEM-EDS a broad distribution of carbon within the wear track (Fig. 5 ). Additionally, XPS analysis indicates that Ti₃C₂Tₓ retains its carbide nature even after tribological stress, rather than converting to an oxide. In summary, under tribological stress, the hybrid coating undergoes a dynamic reorganization that leverages the distinct properties of its components. The Nb₂CTₓ phase, owing to its high tribochemical reactivity, contributes to the formation of an initial sacrificial surface layer. Meanwhile, the Ti₃C₂Tₓ phase, thanks to the strong mechanical stability and the better chemical affinity to the substrate, sustains a low COF by forming a robust layer on which Nb₂CTₓ can slide. Importantly, Nb₂CTₓ is not entirely consumed in the sacrificial process; it remains active within the wear track and continues to facilitate sliding in conjunction with Ti₃C₂Tₓ. This stress-induced redistribution results in a synergistic interaction between the two MXenes, enabling superior tribological performance that neither material achieves on its own, as demonstrated in Fig. 2 . Conclusion This study presented a systematic investigation into the tribological behaviour of MXene hybrid coatings (Nb₂CTₓ and Ti₃C₂Tₓ) under dry sliding conditions. Through a multi-technique characterization approach including SEM-EDS, Raman spectroscopy, XPS, and TEM, we demonstrate that the hybrid MXene coating significantly outperforms the individual components in terms of friction reduction and wear resistance. The hybrid coating exhibits a stable and low coefficient of friction (COF < 0.2), attributed to the formation of a compact, patchy tribofilm. The low and stable COF found at the selected contact pressure (0.48 GPa) makes the hybrid coating competitive in the framework of different solid lubricants (see the list in Table S2). These performances are attributed to the tribofilm forming from a stress-induced adaptive reconfiguration, wherein Ti₃C₂Tₓ preferentially anchors to the substrate due to its superior interfacial bonding, while Nb₂CTₓ migrates toward the sliding interface, acting as a sacrificial layer. This dynamic redistribution results in a stratified tribolayer with enhanced mechanical integrity and tribochemical resilience. Raman and XPS analyses confirm that within the hybrid tribofilm, Ti₃C₂Tₓ retains its carbide nature under tribological stress, while Nb₂CTₓ undergoes partial oxidation, contributing to the formation of a lubricious oxide-rich surface. TEM imaging reveals a nanostructured tribofilm with both crystalline and amorphous domains, further supporting the hypothesis of synergistic interaction between the two MXenes. These findings highlight the potential of hybrid MXenes as a powerful strategy for designing next-generation solid lubricants. By leveraging the complementary properties of different MXene species, it is possible to engineer coatings with tailored tribological performance, opening new avenues for advanced applications in energy-efficient and high-performance mechanical systems. Declarations Acknowledgements The authors thank Ms. Bianca Aigner and AC2T Research GmbH for providing access to laboratory equipment and for their valuable support in the preparation of the coatings. Funding The authors gratefully acknowledge the Austrian Research Promotion Agency (FFG) for funding the infrastructure “ELSA” under grant number 884672. We further acknowledge FFG for funding within the LASER2D project. We also thank the TU Wien Library for its financial support through the Open Access Publishing Fund. Part of this work was carried out as part of the COMET Centre InTribology (FFG no. 906860), a project of the “Excellence Centre for Tribology” (AC2T research GmbH). In Tribology is funded within the COMET – Competence Centres for Excellent Technologies Programme by the federal ministries BMIMI and BMWET as well as the federal states of Niederösterreich and Vorarlberg based on financial support from the project partners involved. COMET is managed by The Austrian Research Promotion Agency (FFG). The authors acknowledge ”Gesellschaft für Forschungsförderung Niederösterreich m.b.H.” through its FTI PhD Funding Programme (FTI22‐D‐018). Author contributions Christina Danecker: Experiments, Analyzation, Characterizations, first draft, Writing Sabine Schwarz: FIB / TEM measurements Marko Piljevic: Raman, Writing Jakob Rath: XPS measurements Martin Nastran, Bernhard Bayer-Skoff: XRD measurements Michael Naguib, Ahmad Majed, Karamullah Eisawi: MXene synthesis, writing Pierluigi Bilotto: Supervision, Writing Carsten Gachot: Supervision, Writing Data availability statement Data will be available upon sensible request Competing interests No competing interests to declare Additional information (Correspondence) References „Energy Technology Perspectives 2020 – Analysis, IEA. Zugegriffen: 21. März 2025. [Online]. Verfügbar unter: https://www.iea.org/reports/energy-technology-perspectives-2020 Holmberg, K. & Erdemir, A. „Influence of tribology on global energy consumption, costs and emissions, Friction , Bd. 5, Nr. 3, S. 263–284, Sep. (2017). 10.1007/s40544-017-0183-5 Wang, H. et al. „Tribological Behavior of NiAl-Layered Double Hydroxide Nanoplatelets as Oil-Based Lubricant Additives, ACS Appl. Mater. Interfaces , Bd. 9, Nr. 36, S. 30891–30899, Sep. (2017). 10.1021/acsami.7b10515 Naguib, M., Mochalin, V. N., Barsoum, M. W. & Gogotsi, Y. „25th Anniversary Article: MXenes: A New Family of Two-Dimensional Materials. Adv. Mater. Bd. 26 (Nr. 7), 992–1005. 10.1002/adma.201304138 (2014). Reeves, C. J., Siddaiah, A. & Menezes, P. L. „A Review on the Science and Technology of Natural and Synthetic Biolubricants, J. Bio- Tribo-Corros. , Bd. 3, Nr. 1, S. 11, Jan. (2017). 10.1007/s40735-016-0069-5 Lugt, P. M. „A Review on Grease Lubrication in Rolling Bearings. Tribol Trans. Bd. 52 (Nr. 4), 470–480. 10.1080/10402000802687940 (Juni 2009). Cai, M., Zhao, Z., Liang, Y., Zhou, F. & Liu, W. „Alkyl Imidazolium Ionic Liquids as Friction Reduction and Anti-Wear Additive in Polyurea Grease for Steel/Steel Contacts. Tribol Lett. Bd. 40 (Nr. 2), 215–224. 10.1007/s11249-010-9624-2 (Nov. 2010). Rosenkranz, A. „Multi-layer Ti3C2Tx-nanoparticles (MXenes) as solid lubricants – Role of surface terminations and intercalated water. Appl. Surf. Sci. Bd. 494 , 13–21. 10.1016/j.apsusc.2019.07.171 (Nov. 2019). D. Akinwande u. a. , „A review on mechanics and mechanical properties of 2D materials—Graphene and beyond. Extreme Mech. Lett , Bd. 13 , S. 42–77, Mai (2017). 10.1016/j.eml.2017.01.008 S. B. Mitta u. a. , „Electrical characterization of 2D materials-based field-effect transistors, 2D Mater. , Bd. 8, Nr. 1, S. 012002, Nov. (2020). 10.1088/2053-1583/abc187 Zhang, S., Ma, T., Erdemir, A. & Li, Q. „Tribology of two-dimensional materials: From mechanisms to modulating strategies. Mater. Today . Bd. 26 , 67–86. 10.1016/j.mattod.2018.12.002 (Juni 2019). Lian, W., Mai, Y., Liu, C., Zhang, L. & Li, S. Jie, „Two-dimensional Ti3C2 coating as an emerging protective solid-lubricant for tribology. Ceram. Int. Bd. 44 , 20154–20162. 10.1016/j.ceramint.2018.07.309 (Nov. 2018). Wu, F. B., Zhou, S. J., Ouyang, J. H., Wang, S. Q. & Chen, L. „Structural Superlubricity of Two-Dimensional Materials: Mechanisms, Properties, Influencing Factors, and Applications, Lubricants , Bd. 12, Nr. 4, Art. Nr. 4, Apr. (2024). 10.3390/lubricants12040138 M. Naguib u. a. , „Two-Dimensional Nanocrystals Produced by Exfoliation of Ti3AlC2. Adv Mater , Bd. 23 , Nr. 37, S. 4248–4253, (2011). 10.1002/adma.201102306 Sokol, M., Natu, V., Kota, S. & Barsoum, M. W. „On the Chemical Diversity of the MAX Phases, Trends Chem. , Bd. 1, Nr. 2, S. 210–223, Mai (2019). 10.1016/j.trechm.2019.02.016 Naguib, M., Barsoum, M. W. & Gogotsi, Y. „Ten Years of Progress in the Synthesis and Development of MXenes. Adv. Mater. Bd. 33 , 2103393. 10.1002/adma.202103393 (2021). M. Ostermann u. a. , „Pulsed Electrochemical Exfoliation for an HF-Free Sustainable MXene Synthesis, Small , Bd. 21, Nr. 22, S. 2500807, (2025). 10.1002/smll.202500807 Hantanasirisakul, K. & Gogotsi, Y. „Electronic and Optical Properties of 2D Transition Metal Carbides and Nitrides (MXenes). Adv. Mater. Bd. 30 , 1804779. 10.1002/adma.201804779 (2018). Gao, G., O’Mullane, A. P. & Du, A. „2D MXenes: A New Family of Promising Catalysts for the Hydrogen Evolution Reaction. ACS Catal. Bd. 7 (Nr. 1), 494–500. 10.1021/acscatal.6b02754 (Jan. 2017). Mojtabavi, M., VahidMohammadi, A., Liang, W. & Beidaghi, M. März, und M. Wanunu, „Single-Molecule Sensing Using Nanopores in Two-Dimensional Transition Metal Carbide (MXene) Membranes, ACS Nano , Bd. 13 , Nr. 3, S. 3042–3053, (2019). 10.1021/acsnano.8b08017 Li, Z. et al. „Surface Nanopore Engineering of 2D MXenes for Targeted and Synergistic Multitherapies of Hepatocellular Carcinoma. Adv. Mater. Bd. 30 , 1706981. 10.1002/adma.201706981 (2018). Nr. 25. Sundaram, A. „Engineering of 2D transition metal carbides and nitrides MXenes for cancer therapeutics and diagnostics. J. Mater. Chem. B . Bd. 8 , 4990–5013. 10.1039/D0TB00251H (Juni 2020). M. R. Lukatskaya u. a. , „Ultra-high-rate pseudocapacitive energy storage in two-dimensional transition metal carbides. Nat Energy , Bd. 6 , (2017). 10.1038/nenergy.2017.105 Xing, C. „Two-Dimensional MXene (Ti3C2)-Integrated Cellulose Hydrogels: Toward Smart Three-Dimensional Network Nanoplatforms Exhibiting Light-Induced Swelling and Bimodal Photothermal/Chemotherapy Anticancer Activity. ACS Appl. Mater. Interfaces . Bd. 10 , 27631–27643. 10.1021/acsami.8b08314 (2018). Rasool, K. et al. „Antibacterial Activity of Ti3C2Tx MXene. ACS Nano . Bd. 10 (Nr. 3), 3674–3684. 10.1021/acsnano.6b00181 (März 2016). S. Luo u. a. , „Tensile behaviors of Ti3C2Tx (MXene) films, Nanotechnology , Bd. 31, Nr. 39, S. 395704, Juli (2020). 10.1088/1361-6528/ab94dd Rosenkranz, A., Righi, M. C., Sumant, A. V., Anasori, B. & Mochalin, V. N. „Perspectives of 2D MXene Tribology. Adv. Mater. Bd. 35 (Nr. 5), 2207757. 10.1002/adma.202207757 (2023). Marian, M. „Mxene nanosheets as an emerging solid lubricant for machine elements – Towards increased energy efficiency and service life. Appl. Surf. Sci. Bd. 523 10.1016/j.apsusc.2020.146503 (2020). Wyatt, B. C., Rosenkranz, A. & Anasori, B. „2D MXenes: Tunable Mechanical and Tribological Properties. Adv. Mater. Bd. 33 , 10.1002/adma.202007973 (2021). Nr. 17, S. 2007973. Feng, Q. et al. „Enhancing the tribological performance of Ti3C2 MXene modified with tetradecylphosphonic acid. Colloids Surf. Physicochem Eng. Asp . Bd. 625 , 126903. 10.1016/j.colsurfa.2021.126903 (Sep. 2021). P. G. Grützmacher u. a. , „Superior Wear-Resistance of Ti3C2Tx Multilayer Coatings, ACS Nano , Bd. 15, Nr. 5, S. 8216–8224, Mai (2021). 10.1021/acsnano.1c01555 Boidi, G. „Influence of ex-situ annealing on the friction and wear performance of multi-layer Ti3C2T x coatings. Appl. Mater. Today . Bd. 36 10.1016/j.apmt.2023.102020 (2024). S. 102020, Feb. Naguib, M. et al. „New Two-Dimensional Niobium and Vanadium Carbides as Promising Materials for Li-Ion Batteries, J. Am. Chem. Soc. , Bd. 135, Nr. 43, S. 15966–15969, Okt. (2013). 10.1021/ja405735d Ponnalagar, D., Hang, D. R., Islam, S. E., Liang, C. T. & Chou, M. M. C. „Recent progress in two-dimensional Nb2C MXene for applications in energy storage and conversion. Mater. Des. Bd. 231 , 112046. 10.1016/j.matdes.2023.112046 (Juli 2023). Nasrin, K., Sudharshan, V., Arunkumar, M. & Sathish, M. „2D/2D Nanoarchitectured Nb2C/Ti3C2 MXene Heterointerface for High-Energy Supercapacitors with Sustainable Life Cycle. ACS Appl. Mater. Interfaces . Bd. 14 , 21038–21049. 10.1021/acsami.2c02871 (Mai 2022). Bi, M., Miao, Y., Li, W. & Yao, J. „Niobium carbide MXene-optics fiber-sensor for high sensitivity humidity detection, Appl. Phys. Lett. , Bd. 120, Nr. 2, S. 021103, Jan. (2022). 10.1063/5.0064005 J. Yin u. a. , „Nb2C MXene-Functionalized Scaffolds Enables Osteosarcoma Phototherapy and Angiogenesis/Osteogenesis of Bone Defects. Nano-Micro Lett , Bd. 13 , Nr. 1, S. 30, Jan. (2021). 10.1007/s40820-020-00547-6 Zhou, X., Guo, Y., Wang, D. & Xu, Q. „Nano friction and adhesion properties on Ti3C2 and Nb2C MXene studied by AFM. Tribol Int. Bd. 153 , 106646. 10.1016/j.triboint.2020.106646 (Jan. 2021). Cheng, H. & Zhao, W. „Regulating the Nb2C nanosheets with different degrees of oxidation in water lubricated sliding toward an excellent tribological performance, Friction , Bd. 10, Nr. 3, S. 398–410, März (2022). 10.1007/s40544-020-0469-x Chhattal, M. „Unveiling the tribological potential of MXenes-current understanding and future perspectives. Adv. Colloid Interface Sci. Bd. 321 10.1016/j.cis.2023.103021 (2023). S. 103021, Nov. Marquis, E., Cutini, M., Anasori, B., Rosenkranz, A. & Righi, M. C. „Nanoscale MXene Interlayer and Substrate Adhesion for Lubrication: A Density Functional Theory Study, ACS Appl. Nano Mater. , Bd. 5, Nr. 8, S. 10516–10527, Aug. (2022). 10.1021/acsanm.2c01847 M. Piljević u. a. , „Evaluation of O-terminated sustainable EC-MXene as solid lubricant, 28. ChemRxiv . Mai (2025). 10.26434/chemrxiv-2025-tzhc7 Habib, T. et al. „Oxidation stability of Ti3C2Tx MXene nanosheets in solvents and composite films, Npj 2D Mater. Appl. , Bd. 3, Nr. 1, S. 1–6, Feb. (2019). 10.1038/s41699-019-0089-3 Marian, M. „Effective usage of 2D MXene nanosheets as solid lubricant – Influence of contact pressure and relative humidity. Appl. Surf. Sci. Bd. 531 10.1016/j.apsusc.2020.147311 (2020). S. 147311, Nov. J. Simon u. a. , „Tailoring optical response of MXene thin films. Nanophotonics Apr (2025). 10.1515/nanoph-2024-0769 158295, S. & Dez Zambrano-Mera u. a. , „Solid lubrication performance of sandwich Ti3C2Tx-MoS2 composite coatings. Appl. Surf. Sci. Bd. 640 10.1016/j.apsusc.2023.158295 (2023). Shirley, D. A. „High-resolution x-ray photoemission spectrum of the valence bands of gold, Phys. Rev. B , Bd. 5, Nr. 12, S. 4709–4714, (1972). 10.1103/PhysRevB.5.4709 Scofield, J. H. „Hartree-Slater subshell photoionization cross-sections at 1254 and 1487 eV. J. Electron. Spectrosc. Relat. Phenom. Bd. 8 (Nr. 2), 129–137. 10.1016/0368-2048(76)80015-1 (Jan. 1976). „More Molybdenum Values. Zugegriffen: 8. Mai 2025. [Online]. Verfügbar unter: http://www.xpsfitting.com/2014/05/more-molybdenum-values.html Beamson, G. & Briggs, D. R. „High Resolution XPS of Organic Polymers: The Scienta ESCA300 Database, 1992. [Online]. Verfügbar unter: https://api.semanticscholar.org/CorpusID:92946956 Liu, Y., Zhang, X., Dong, S., Ye, Z. & Wei, Y. „Synthesis and tribological property of Ti3C2TXnanosheets. J. Mater. Sci. Bd. 52 (Nr. 4), 2200–2209. 10.1007/s10853-016-0509-0 (Feb. 2017). A. N. Giordano u. a. , „Raman Spectroscopy and Laser-Induced Surface Modification of Nb2CTx MXene, ACS Mater. Lett. , Bd. 6, Nr. 8, S. 3264–3271, Aug. (2024). 10.1021/acsmaterialslett.4c00922 Blau, P. J. „On the nature of running-in, Tribol. Int. , Bd. 38, Nr. 11, S. 1007–1012, Nov. (2005). 10.1016/j.triboint.2005.07.020 M. Chhattal u. a. , „Solid lubrication performance of Ti2CTx coatings with reduced friction and extended durability. Tribol Int , Bd. 194 , S. 109535, Juni (2024). 10.1016/j.triboint.2024.109535 Hwang, D. H., Kim, D. E. & Lee, S. J. „Influence of wear particle interaction in the sliding interface on friction of metals. Wear 225–229. 10.1016/S0043-1648(98)00371-8 (1999). Nr. I. Mansour, H. et al. „Structural, optical, magnetic and electrical properties of hematite (α-Fe2O3) nanoparticles synthesized by two methods: polyol and precipitation, Appl. Phys. A , Bd. 123, Nr. 12, S. 787, Nov. (2017). 10.1007/s00339-017-1408-1 Additional Declarations No competing interests reported. Supplementary Files SuportiveInformationPaperNb2CTxTi3C2Txv8.docx Cite Share Download PDF Status: Published Journal Publication published 22 Dec, 2025 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 30 Sep, 2025 Reviews received at journal 29 Sep, 2025 Reviews received at journal 25 Sep, 2025 Reviewers agreed at journal 21 Sep, 2025 Reviewers agreed at journal 20 Sep, 2025 Reviewers agreed at journal 19 Sep, 2025 Reviewers invited by journal 18 Sep, 2025 Editor invited by journal 18 Sep, 2025 Editor assigned by journal 17 Sep, 2025 Submission checks completed at journal 12 Sep, 2025 First submitted to journal 09 Sep, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7574829","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":522380873,"identity":"f90a5cee-6265-4ed9-8307-923145210015","order_by":0,"name":"Christina Danecker","email":"","orcid":"","institution":"TU Wien","correspondingAuthor":false,"prefix":"","firstName":"Christina","middleName":"","lastName":"Danecker","suffix":""},{"id":522380874,"identity":"de45704e-52f9-4df3-901d-9d7ed89955a5","order_by":1,"name":"Sabine Schwarz","email":"","orcid":"","institution":"TU Wien","correspondingAuthor":false,"prefix":"","firstName":"Sabine","middleName":"","lastName":"Schwarz","suffix":""},{"id":522380875,"identity":"e5475604-6f78-43aa-82ed-24e0756a49cc","order_by":2,"name":"Marko Piljevic","email":"","orcid":"","institution":"AC2T research GmbH","correspondingAuthor":false,"prefix":"","firstName":"Marko","middleName":"","lastName":"Piljevic","suffix":""},{"id":522380876,"identity":"182495ff-9004-44eb-9eea-e9eacd5687aa","order_by":3,"name":"Jakob Rath","email":"","orcid":"","institution":"TU Wien","correspondingAuthor":false,"prefix":"","firstName":"Jakob","middleName":"","lastName":"Rath","suffix":""},{"id":522380877,"identity":"0e6783a8-7651-4e3d-9861-c3801981b625","order_by":4,"name":"Martin Nastran","email":"","orcid":"","institution":"TU Wien","correspondingAuthor":false,"prefix":"","firstName":"Martin","middleName":"","lastName":"Nastran","suffix":""},{"id":522380878,"identity":"797014b4-1055-4faa-bcc8-de528128109e","order_by":5,"name":"Bernhard Bayer-Skoff","email":"","orcid":"","institution":"TU Wien","correspondingAuthor":false,"prefix":"","firstName":"Bernhard","middleName":"","lastName":"Bayer-Skoff","suffix":""},{"id":522380879,"identity":"19a64bc0-9ce0-41e5-ae3b-3d57a66c6685","order_by":6,"name":"Michael Naguib","email":"","orcid":"","institution":"Tulane University","correspondingAuthor":false,"prefix":"","firstName":"Michael","middleName":"","lastName":"Naguib","suffix":""},{"id":522380880,"identity":"2c3b60a9-eb41-4323-b5c3-3ccd0742c1d9","order_by":7,"name":"Ahmad Majed","email":"","orcid":"","institution":"Tulane University","correspondingAuthor":false,"prefix":"","firstName":"Ahmad","middleName":"","lastName":"Majed","suffix":""},{"id":522380881,"identity":"4d632994-0dfb-44e3-a7a8-b3227b5c64be","order_by":8,"name":"Karamullah Eisawi","email":"","orcid":"","institution":"Tulane University","correspondingAuthor":false,"prefix":"","firstName":"Karamullah","middleName":"","lastName":"Eisawi","suffix":""},{"id":522380882,"identity":"e3289817-f782-43f8-936f-8720c1c21080","order_by":9,"name":"Pierluigi Bilotto","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABKElEQVRIie2QMUsDMRSAXwncLdGsOSr6Fx7coGK5/pWEwE2HCIJ0KgfCuVRdK/6ZK4FO4mxx6SE4FTxwqXCgiVVamgNXh3zwkpDHl/deADye/wgxMQcOAVAo5/YmzM2CfyjiVxGAHKjeVES7trqm9mAUrtzcJochmdayOEpuYGdSikEzZNHbtEvPeqcQ6jl8LB3l+DJQY1lwVcCuKMUD8uheBV2K6TnQFDsjtwpqGoNVzCxYygI5PhslQy1zyEy3bQp731Jm2iqfMmcL6DStVYhVkrXyRKxSypxnQFqqmFliEI9cBOR7lji6G6n4pEFl3nlFvZe6P8b0C9QXw/7B1bWu68E+Y+Gkmo2bRN4yVVWLntvYzy5zsp0KTJSOsFb6LTmPx+PxrPgCOqFfcgSmbRcAAAAASUVORK5CYII=","orcid":"","institution":"TU Wien","correspondingAuthor":true,"prefix":"","firstName":"Pierluigi","middleName":"","lastName":"Bilotto","suffix":""},{"id":522380883,"identity":"8a2a7d7d-ce03-40ec-aa96-11c6db0f707e","order_by":10,"name":"Carsten Gachot","email":"","orcid":"","institution":"TU Wien","correspondingAuthor":false,"prefix":"","firstName":"Carsten","middleName":"","lastName":"Gachot","suffix":""}],"badges":[],"createdAt":"2025-09-09 14:23:26","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7574829/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7574829/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-025-32533-6","type":"published","date":"2025-12-22T15:58:07+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":92507972,"identity":"5a51faf0-404b-4377-a5fd-c04ecd4ae18d","added_by":"auto","created_at":"2025-09-30 12:54:35","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":6189994,"visible":true,"origin":"","legend":"","description":"","filename":"PaperNb2CTxTi3C2Txv9.docx","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/d1c9129fcd80a69d180f58fa.docx"},{"id":92507967,"identity":"9ba194d2-90ee-457e-8b3b-7d4df02eaed1","added_by":"auto","created_at":"2025-09-30 12:54:35","extension":"json","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":11452,"visible":true,"origin":"","legend":"","description":"","filename":"e0e6f50a79c743ee98928f7926de0100.json","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/e3d8b5784de12521029fb5b9.json"},{"id":92509471,"identity":"58aa0dcc-f521-44c0-80ce-498f6629f965","added_by":"auto","created_at":"2025-09-30 13:10:36","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":28363035,"visible":true,"origin":"","legend":"","description":"","filename":"SuportiveInformationPaperNb2CTxTi3C2Txv8.docx","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/9900cad80a39d974bc994396.docx"},{"id":92507973,"identity":"262a4d42-c498-42a8-8680-94243179cd27","added_by":"auto","created_at":"2025-09-30 12:54:35","extension":"xml","order_by":3,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":137564,"visible":true,"origin":"","legend":"","description":"","filename":"e0e6f50a79c743ee98928f7926de01001enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/0314cdacf480d2e8e413330f.xml"},{"id":92508389,"identity":"40e1385a-6465-4fc0-855e-c484949cefdd","added_by":"auto","created_at":"2025-09-30 13:02:35","extension":"png","order_by":4,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":1737996,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/6076fcf79ae9aedc091f91b1.png"},{"id":92507976,"identity":"4c3c9f40-0081-476a-8dbd-207e1be92104","added_by":"auto","created_at":"2025-09-30 12:54:35","extension":"jpeg","order_by":5,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":849416,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/ce3610c0e2e8146f84a98d76.jpeg"},{"id":92508390,"identity":"b805ad29-42d5-41ad-a2bf-cced090e80e5","added_by":"auto","created_at":"2025-09-30 13:02:35","extension":"png","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":322047,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/73c1955b6287b5494537622d.png"},{"id":92508391,"identity":"018f63fe-718a-49ff-82a8-fc144332ee13","added_by":"auto","created_at":"2025-09-30 13:02:36","extension":"png","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":934777,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/6de2975999eb127234c32d6c.png"},{"id":92508392,"identity":"ba629ee4-b305-47bd-b0a4-d1c2ff2e2f3d","added_by":"auto","created_at":"2025-09-30 13:02:36","extension":"jpeg","order_by":8,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":1310858,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/aa76c58926dd556d6f24697f.jpeg"},{"id":92508393,"identity":"935a5759-97e5-4fb1-b3a5-7226d157c5da","added_by":"auto","created_at":"2025-09-30 13:02:36","extension":"png","order_by":9,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":919802,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/bb85e1d9ecc112a919609d00.png"},{"id":92507980,"identity":"5de433ca-9f50-4ff0-8794-e0af038b58b6","added_by":"auto","created_at":"2025-09-30 12:54:35","extension":"png","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":217312,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/4228a5b6e8f00528f1cb304b.png"},{"id":92507986,"identity":"94cad12f-7064-4760-be93-3ea7352a1a81","added_by":"auto","created_at":"2025-09-30 12:54:36","extension":"png","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":102513,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/b245b6795bc6d404f8bb0c7e.png"},{"id":92507984,"identity":"fcdd7910-af2f-4d1c-9b52-345b5276f33f","added_by":"auto","created_at":"2025-09-30 12:54:36","extension":"png","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":47045,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/fd8c18c3abeafd18b025f4c4.png"},{"id":92507981,"identity":"86fc8a2d-4cc7-4db2-b892-a43c60c46074","added_by":"auto","created_at":"2025-09-30 12:54:35","extension":"png","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":210211,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/8f854958f7a4d77831f4fcc0.png"},{"id":92507989,"identity":"d7e80ce4-667c-41b2-8aa6-49f0d7c9890f","added_by":"auto","created_at":"2025-09-30 12:54:36","extension":"png","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":135580,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/39d61a419dbd25f415b912da.png"},{"id":92507990,"identity":"3ad0d824-9004-4b84-963d-f7724464be64","added_by":"auto","created_at":"2025-09-30 12:54:36","extension":"png","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":203236,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/d64928007326c51fd7613b23.png"},{"id":92507991,"identity":"133e8fa9-0f97-41ce-abcc-5cca0905017f","added_by":"auto","created_at":"2025-09-30 12:54:36","extension":"xml","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":138839,"visible":true,"origin":"","legend":"","description":"","filename":"e0e6f50a79c743ee98928f7926de01001structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/91aad66bca33223e037d7ffd.xml"},{"id":92507983,"identity":"8696bf2e-bf39-4610-9b7a-1a2f05101f8b","added_by":"auto","created_at":"2025-09-30 12:54:36","extension":"html","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":148182,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/d967d3c0fbe2b9d94ce9389a.html"},{"id":92507969,"identity":"a03b5fa4-b0b5-4e7d-9fc9-4d09bcabb5db","added_by":"auto","created_at":"2025-09-30 12:54:35","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":641262,"visible":true,"origin":"","legend":"\u003cp\u003eSEM and TEM images of the as-synthesized MXenes Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e and Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e. (a) SEM image of Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e flakes and (b) corresponding morphology of Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e. (c) TEM image of a Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e and the corresponding SAED pattern from position 1 in (c1). (d) High-resolution TEM bright field imaging showing the layered structure of Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e, with increased magnification (d1), providing an interlayer spacing of 1.28 nm. (e) and (e1) show TEM and SAED images of Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e. (f) and (f1) show a different region of Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e illustrating the layered structure.\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/4311e477d58488a22bc17a0b.png"},{"id":92508388,"identity":"27aa8fe7-9c44-4503-acb0-d69283f531a7","added_by":"auto","created_at":"2025-09-30 13:02:35","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":406695,"visible":true,"origin":"","legend":"\u003cp\u003eTime-dependent behaviour of the coefficients of friction (a) for all MXene coated steel samples against an Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e counterbody. The average values of three replicates are represented by the solid line, with the corresponding standard deviations indicated by the shaded area. The corresponding wear tracks are shown in for (b) Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e, (c) Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e, and (d) the hybrid coating.\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/530b4cb400bfe9feb28e7092.png"},{"id":92507971,"identity":"e42cc943-6bcb-46a9-9489-3b54a2d67578","added_by":"auto","created_at":"2025-09-30 12:54:35","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":306802,"visible":true,"origin":"","legend":"\u003cp\u003eAverage Raman spectra measured on wear tracks after tribological tests using different MXenes (n≥2): (a) Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e, (b) Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/4c87c77150abe0ad4ca82fb3.png"},{"id":92507970,"identity":"18d2e0b9-7cc7-4c83-aaa2-84ed9245d962","added_by":"auto","created_at":"2025-09-30 12:54:35","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":413169,"visible":true,"origin":"","legend":"\u003cp\u003e(a) SEM micrograph of the substrates wear scar after tribological tests on Hybrid MXene coating, (b) Average Raman spectra measured on counterbody areas identified by SEM (same colour code): n ≥ 3, n=number of tests\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/9a5682f4e93acb0a6b9de092.png"},{"id":92507978,"identity":"c27cc86b-4996-45e1-b47a-4f681c11da6b","added_by":"auto","created_at":"2025-09-30 12:54:35","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":461051,"visible":true,"origin":"","legend":"\u003cp\u003eScanning transmission electron microscopy (STEM)-EDS analysis of the wear track for the hybrid coated sample. (a1) shows the STEM HAADF image and (a2) the corresponding EDS elemental overlay image, respectively, with colour-coded distributions. Elemental maps are shown individually for (a3) titanium, (a4) niobium, (a5) carbon, (a6) oxygen and (a7) iron. (A localized dark green signal in the left region of (a2) corresponds to tungsten (W), which was applied as a protective layer during FIB sample preparation.)\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/826bf8d6efed89038d4f0b74.png"},{"id":92507977,"identity":"6a82de93-2be9-4261-a393-72159e3d156a","added_by":"auto","created_at":"2025-09-30 12:54:35","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":351190,"visible":true,"origin":"","legend":"\u003cp\u003eTEM analysis of the wear track of the hybrid coating. (a1) shows a TEM overview image of the lamella with marked regions Zone 1 and Zone 2. For more detailed analysis, (a2) presents a bright field TEM image of the tribofilm in Zone 1, while (a3) displays the corresponding selected area electron diffraction (SAED) pattern at position 1, confirming nanocrystallinity. A high-resolution TEM image in (a4) further reveals the layered structure at position 1. (b1) displays a magnified overview of Zone 2, while (b2) shows a higher-magnification TEM image of this zone. The corresponding SAED pattern of position 2 is shown in (b3) and confirms the single crystallinity of the Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003e-MXenes, which is also discussed in more detail in the Supportive Information in Figure S7. The high-resolution TEM image in (b4) provides further insights into the nanoscale layering and its arrangement within the tribofilm at this location.\u003c/p\u003e","description":"","filename":"image6.png","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/dd7f554a081929ac0aae1782.png"},{"id":99172640,"identity":"026f9f31-4a08-4e5b-891e-261f0aa26ca6","added_by":"auto","created_at":"2025-12-29 16:11:13","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3415215,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/0d49703c-f321-4667-b581-6baac4ecfebb.pdf"},{"id":92507992,"identity":"e3f4cb06-c27d-4111-a3b1-a5cc90e00903","added_by":"auto","created_at":"2025-09-30 12:54:36","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":28363035,"visible":true,"origin":"","legend":"","description":"","filename":"SuportiveInformationPaperNb2CTxTi3C2Txv8.docx","url":"https://assets-eu.researchsquare.com/files/rs-7574829/v1/bc2918c3b90c4f7e2555b4f4.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eHybrid MXene Coatings: Unlocking Synergistic Lubrication Properties of Ti₃C₂Tₓ and Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e MXenes for Improved Tribological Performance\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe transition to sustainable energy production and transportation is essential for reducing emissions and addressing climate change. Securing energy efficiency is equally important in the endeavour of achieving sustainability goals. The International Energy Agency (IEA) highlights that about 30% of cumulative CO₂ emission reductions can be achieved by promoting energy efficiency in technologies and the adoption of less energy-intensive materials and processes [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eTribology, the science of friction, wear and lubrication, plays a crucial role in enhancing the efficiency, reliability, and lifespan of mechanical systems. Indeed, tribological losses are responsible of approximately 23% of global energy consumption. Therefore, with almost all industry sectors depending on machines with moving components, reducing friction-related losses is fundamental to improving overall performances [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAs friction and wear lead to considerable material and energy losses in mechanical systems [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], the simplest and most efficient solution is the application of a lubricant to separate the interacting surfaces [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Depending on the application and environmental conditions, various lubricants are used to reduce friction and wear, such as mineral- or synthetic oils [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], greases [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], ionic liquids [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e], and solid lubricants [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. However, as technological and industrial needs become more demanding for high performances in complex scenarios (e.g., aerospace), the scientific research is stirred toward evaluating the tribological performances of novel advanced materials.\u003c/p\u003e\u003cp\u003eAmong these, two-dimensional (2D) materials with layered structures have emerged as a highly researched class of solid lubricants, due to their exceptional mechanical, physical, chemical, and tribological properties [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. 2D materials are thin, sheet-like structures that consist of one or a few atomic layers in thickness [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. These layered materials can form easy-to-shear tribolayers, which separate sliding surfaces and help reduce friction and wear [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The functionality of 2D materials is based on weak van der Waals interactions between the layers, enabling them to slide under low shear forces. At the same time, strong in-plane covalent bonds hold the atoms together, allowing the layers to move easily without separating completely [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eMXenes, 2D transition metal carbides, nitrides, and carbonitrides, have recently received considerable attention [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. They are produced by removing the A-group layer atoms (e.g. Al) from M\u003csub\u003en+1\u003c/sub\u003eAX\u003csub\u003en\u003c/sub\u003e or MAX phases [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. After removing the A group elements, multilayered MXenes remain, described by the chemical formula M\u003csub\u003en+1\u003c/sub\u003eX\u003csub\u003en\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e (n\u0026thinsp;=\u0026thinsp;1 to 4). The surface is terminated with functional groups such as -O, -OH, -F and/or -Cl, collectively represented as 'Tₓ', depending on the specific etching route used (HF, MILD method, Electrochemistry or Molten Salt) [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. MXenes demonstrate application potential in several fields, such as energy storage [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], catalysis [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] biomedical applications for biosensors [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] or drug delivery [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. One of the most well-known and extensively studied MXene is titanium carbide (Ti₃C₂Tₓ), produced by selective etching of Ti₃AlC₂. Its properties include high electrical conductivity [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], biocompatibility [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], antibacterial activity [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] and good mechanical characteristics such as tensile strength, elastic modulus, and fracture strain [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Due to their chemical and structural versatility combined with their easy-to-shear ability and strong interfacial bonding, Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e have emerged as a promising material for tribological applications [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e], [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e], including their use as lubricant additives [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e], [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] and solid lubricant coatings [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e], [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAnother notable member of the MXene family is niobium carbide (Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e) [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e has been used in various energy applications due to its exceptional electrical conductivity, outstanding chemical stability and high electronic conductivity [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. These applications include supercapacitors [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e], rechargeable batteries [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e], sensors [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e], and even biomedical uses [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eBeyond energy-related applications, recent studies have also explored the tribological potential of Nb based MXenes. By using Atomic Force Microscopy (AFM), it was observed that Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e MXenes exhibited lower friction and adhesion forces compared to Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e, with both properties decreasing as the temperature increased [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. The different behaviours in friction and adhesion were attributed to differences in surface dipole moment density, with Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e having a denser surface compared to Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eNb\u003csub\u003e2\u003c/sub\u003eC nanosheets with varying degrees of oxidation were applied as solid lubricant additives in water-based lubrication systems [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. The results showed that a medium oxidation degree significantly reduced the coefficient of friction by 90.3% and the wear rate by 73.1% compared to pure water, demonstrating the added value of Nb\u003csub\u003e2\u003c/sub\u003eC [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThese exceptional tribological characteristics of MXenes (Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e and Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e alike) are strongly influenced by factors such as the number of nanosheets, the orientation of individual monolayers, the lateral flake size, the film thickness, the interlayer interactions, the substrate interaction, and surface terminations [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. The latter, directly affect the adhesion of both the individual layer and at the interface with the substrate, as presented in a recent density functional theory (DFT) study taking iron and iron oxide as substrates [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. DFT suggests that tuning the density of -OH and -F terminations may lead to a significant improvement in the friction and wear behaviour of MXenes [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e], as proven in our recent work on the tribological performances of electrochemically synthesized MXenes [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe oxidation properties of MXenes in air, liquid, and solid environments reveals their strong susceptibility to degradation as a key challenge. For instance, Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e flakes in liquids is prone to form TiO\u003csub\u003e2\u003c/sub\u003e, which reduces conductivity and limits long-term stability [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]. Similarly, at 20% relative humidity, the coefficient of friction of Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e remains stable for about 4000 sliding cycles, whereas at higher humidity levels (approximately 80%), a significant rise in the coefficient of friction is observed [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eNovel strategies are required to overcome specific challenges in MXene tribology such as oxidation stability and tribochemical resilience. The exploration of MXene hybrids is gathering interest owing to the possibility of igniting synergistic effects that may overcome limits of the singular species. For instance, a recent study has shown the ability to tailor the optical properties of Ti₃C₂Tₓ and Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e hybrids [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]. Similarly, Ti₃C₂Tₓ combined to MoS\u003csub\u003e2\u003c/sub\u003e has demonstrated great tribological performances, with a coefficient of friction as low as 0.14 and a wear rate of 0.49 x 10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003e mm\u0026sup3;/Nm [\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eInspired by these works, hereby we investigate the synergistic effect of combining Ti₃C₂Tₓ and Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e to form hybrids with advanced tribological performances.\u003c/p\u003e\u003cp\u003eSpecifically, we evaluate the tribological performance of a spray coated Nb₂CTₓ /Ti₃C₂Tₓ hybrid deposited onto AISI 304 steel substrates, which are then tested under linear sliding conditions against a Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e counterbody. Uncoated AISI 304 steel substrates, Ti₃C₂Tₓ, and Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e coatings were used as reference materials. Detailed post-experimental analysis of the coatings and the corresponding wear tracks provides insight into the underlying mechanisms of the observed tribological behaviour. The hybrid coating exhibited a stable coefficient of friction (COF) below 0.2, demonstrating excellent lubricity. This is attributed to the tribo-induced formation of a compact, patchy tribofilm, which effectively reduces the COF and protects the substrate from wear. Surface analysis of the wear tracks was conducted to investigate the underlying tribochemical processes, using techniques such as Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM).\u003c/p\u003e\u003cp\u003eIn conclusion, we demonstrate that the Nb₂CTₓ/Ti₃C₂Tₓ hybrid coating provides superior tribological performance due to the synergistic interaction between the two MXene species. Under sliding conditions, Nb₂CTₓ and Ti₃C₂Tₓ undergo adaptive reconfiguration aimed at minimizing the COF. Nb₂CTₓ becomes more exposed to the sliding interface, acting as a sacrificial layer that undergoes oxidation, while Ti₃C₂Tₓ preferentially positions itself at the interface with the substrate, enhancing adhesion and contributing to the mechanical robustness of the tribofilm. This dynamic redistribution underscores the complementary roles of the two MXenes in forming a stable, low friction tribolayer.\u003c/p\u003e\u003cp\u003eOur findings present a novel strategy for engineering MXene-based solid lubricant hybrid composites; wherein two-dimensional materials are designed to exhibit enhanced functional behaviour. This methodology leverages the vast compositional diversity of the MXene family and aligns with the growing interest in high-entropy systems. As such, it opens new avenues for both fundamental research in advanced materials and the development of innovative, application-driven solutions for industry.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eSynthesis of Ti\u003csub\u003e3\u003c/sub\u003eAlC\u003csub\u003e2\u003c/sub\u003e and Nb\u003csub\u003e2\u003c/sub\u003eAlC MAX phases\u003c/p\u003e\u003cp\u003eElemental powders of titanium (Ti, -325 mesh, 99%, Thermo Scientific), aluminum (Al, -325 mesh, 99.5%, Thermo Scientific), and graphite (C, 7\u0026ndash;11 \u0026micro;m, 99%, Alfa Aesar) were combined in a Ti:Al:C molar ratio of 3.00:1.20:1.88. The mixture was placed in a high-density polyethylene (HDPE) container along with ten 10 mm yttria-stabilized zirconia (YSZ) balls and mixed using a Turbula T2F mixer at 56 rpm for 3 h. It was then transferred to an alumina crucible and heated in a tube furnace under a continuous argon flow (0.2 L/min). The temperature was increased to 1600\u0026deg;C at a rate of 5\u0026deg;C/min and held for 2 h. After the reaction, the system was allowed to cool naturally to room temperature under inert atmosphere. The resulting lightly sintered Ti\u003csub\u003e3\u003c/sub\u003eAlC\u003csub\u003e2\u003c/sub\u003e brick was ground and sieved to obtain powders smaller than 45 \u0026micro;m. Synthesis of Nb\u003csub\u003e2\u003c/sub\u003eAlC MAX phase followed the same procedure however using elemental powders of niobium, aluminium, and graphite with molar ratios Nb:Al:C of 2.00:1.30:0.95C. After mixing, the mixture was pressed into green pellets 12\u0026ndash;13 g/pellet. The pellets were sintered at 1600\u0026deg;C and held for 4 h.\u003c/p\u003e\u003cp\u003eSynthesis of Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e and Nb\u003csub\u003e2\u003c/sub\u003eC\u003csub\u003ex\u003c/sub\u003e MXene phases\u003c/p\u003e\u003cp\u003eTi\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e was obtained by selectively etching the aluminum layers from Ti₃AlC₂ using an \u003cem\u003ein-situ\u003c/em\u003e HF-generating etchant composed of potassium fluoride (KF, 99%, Thermo Scientific) and hydrochloric acid (HCl, 9 M, Fisher Chemicals). The etching solution was prepared by mixing 20 mL of 9 M HCl per gram of Ti\u003csub\u003e3\u003c/sub\u003eAlC\u003csub\u003e2\u003c/sub\u003e with KF at a molar ratio of 9:1 (KF:Ti₃AlC₂). Ti₃AlC₂ powder was gradually added to the etchant under magnetic stirring at 500 rpm and maintained at 45\u0026deg;C for 48 hours. Following etching, the product was soaked in 9 M HCl for 18 hours to remove excess salts. The resulting powder was then washed by distributing it into 50 mL centrifuge tubes, using one tube per 0.5 g of precursor. Deionized (DI) water was added, followed by centrifugation at 3500 rpm for 2 minutes. The supernatant was discarded, fresh DI water was added, and the sediment was redispersed using a vortex mixer. This process was repeated until the pH of the supernatant exceeded 6. Nb\u003csub\u003e2\u003c/sub\u003eC\u003csub\u003ex\u003c/sub\u003e was produced by inserting Nb\u003csub\u003e2\u003c/sub\u003eAlC powders into hydroflouric acid (HF, 48\u0026ndash;51%, Alfa Aesar) with a ratio of 1 g: 20 ml the sample was stirred at 40\u0026deg;C for 5 days. The washing and filtering steps were similar to that of Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e.\u003c/p\u003e\u003cp\u003eThe morphology of the as-synthesised Ti₃C₂Tₓ and Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e MXenes was characterised by scanning electron microscopy (SEM, FEI Quanta 250 FEG) operated at an acceleration voltage of 5 kV. Secondary electron imaging was performed using an Everhart-Thornley detector (ETD). In addition, TEM (Tecnai F20) was performed at 200 kV acceleration voltage for higher-resolution imaging.\u003c/p\u003e\u003cp\u003eIn addition, X-ray diffraction (XRD) and Raman spectroscopy were performed on both MXene powders to gain further information about their surface terminations. XRD were carried out using a Malvern Panalytical X\u0026rsquo;Pert MPDII equipped with a X\u0026rsquo;Celerator semiconductor detector. Diffraction patterns were recorded over a 2θ range of 5\u0026deg; to 70\u0026deg;, with a total scan duration of 20 min.\u003c/p\u003e\u003cp\u003eA LabRam Aramis Raman microscope (Horiba Jovin Yvon, Germany) is used to record Raman spectra of Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e and Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e MXene powder. Red raman laser with wavelength of 632 nm and laser power of 2 mW is used to excite samples. Spectra were recorded from 100 to 2000 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e with a 1200 mm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e grid. Both powders are tested separately before applying on substrate. Data are evaluated in OriginPro 2023b software, where background is removed and peaks are normalized.\u003c/p\u003e\u003cp\u003eCoating deposition\u003c/p\u003e\u003cp\u003eOverall, four different samples were tested: one uncoated reference and three distinct coating systems \u0026mdash; a pure Ti₃C₂Tₓ coating, a Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e coating, and a hybrid coating composed of a combination of both MXenes. For the hybrid coating Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e were first applied, followed by the same amount of Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e, ensuring a uniform mixture of both materials. These coatings were applied to mirror-polished stainless-steel platelets (AISI 304) with dimensions of 15 x 15 x 2 mm\u0026sup3;, a Young\u0026rsquo;s modulus of 200 GPa, a Poisson\u0026acute;s ratio of 0.29, and an initial roughness S\u003csub\u003eq\u003c/sub\u003e of about 0.18 \u0026micro;m. The solid lubricant coatings were deposited onto these substrates by using the airbrush spray-coating process. Uncoated plates and balls were also tested as reference materials. All MXenes were dispersed separately in ethanol at a concentration of 2 mg/mL, regardless of the composition (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eOverview of the deposited coatings, including their design, thickness and applied volume.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eName\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMaterial / Coating\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSpray volume (mL)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThickness tribofilm (nm)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ereference\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAISI 304\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTi\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMXene Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1383.2\u0026nbsp;\u0026plusmn;\u0026nbsp;142\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMXene Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e202.1\u0026nbsp;\u0026plusmn;\u0026nbsp;56\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHybrid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCombination of Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e\u0026nbsp;+\u0026nbsp;Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4 (2\u0026nbsp;+\u0026nbsp;2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e230.5\u0026nbsp;\u0026plusmn;\u0026nbsp;82\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe following steps were taken to prepare the dispersion. The dispersions were first homogenised using a shear mixer (T 25 basic IKA\u0026reg; ULTRA-TURRAX\u0026reg;) for 5 minutes at 11000 rpm. To improve the dispersion and distribution of the nanosheets, tip sonication (QSONICA CL-18 Sonicators) was applied for 1 h (5 s on, 5 s off, 50 W power), followed by 2 h of bath sonication. Directly afterwards, 4 mL of the dispersion was transferred via a syringe into a self-build spray coating set-up. The distance between nozzle and steel substrate was maintained at 10 cm, and the air pressure during spray-coating at 1,5 bar. To ensure rapid solvent evaporation, prevent droplet formation, and achieve uniform coatings the substrates were pre-heated and placed on a heating plate set to 80\u0026deg;C during deposition.\u003c/p\u003e\u003cp\u003eTo fabricate the hybrid coating, 2 mL of each MXene dispersion were sprayed onto the substrate, starting with Nb₂CT\u003csub\u003ex\u003c/sub\u003e followed by Ti₃C₂Tₓ, resulting in a total spray volume of 4 mL. To prevent cross-contamination and ensure material purity, two identical airbrushes of the same model were used - one for each dispersion.\u003c/p\u003e\u003cp\u003eTribological experiments\u003c/p\u003e\u003cp\u003eThe tribological performance of the different solid lubricant coatings were evaluated using a ball-on-disc tribometer (Rtec Instruments, MFT-2000A) in linear sliding mode. The counterbody material was Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e with a diameter of 6 mm. The linear sliding velocity was set to 1 mm/s, stroke length to 1 mm, the normal force to 0.25 N with a calculated hertzian contact pressure of 0.48 GPa, which is in the operating range of many machine elements such as journal bearings, and the test duration to 30 min. A case of moderate contact stresses is reflected in the initial contact pressure at the contact centre. The tests were carried out at room temperature between 20.2\u0026deg;C and 23.5\u0026deg;C and the relative humidity ranged between 20.5% and 25%. All experiments were performed three times to ensure reproducibility and statistical significance, as well as to calculate the mean values and error bars.\u003c/p\u003e\u003cp\u003eSurface characterization of the wear track\u003c/p\u003e\u003cp\u003eBefore and after tribological experiments, all samples were analysed by confocal laser scanning microscopy (CLSM, Keyence VK-X1100).\u003c/p\u003e\u003cp\u003eSurface morphology and wear tracks were analysed using a SEM equipped with an ETD detector. Imaging was carried out in conjunction with the preparation of cross sections and TEM lamellae prepared using a ThermoFisher Scios II dual beam system.\u003c/p\u003e\u003cp\u003eSurface sensitive chemical characterisation was carried out using X-ray photoelectron spectroscopy (XPS, PHI Versa Probe III-spectrometer) equipped with a monochromatic Al-Kα X-ray source and a hemispherical analyser (acceptance angle: \u0026plusmn;20\u0026deg;). Pass energies of 140 eV and 27 eV and step widths of 0.5 eV and 0.05 eV were used for survey and detail spectra, respectively. (Excitation energy: 1486.6 eV Beam energy and spot size: 2 W onto 100 \u0026micro;m; Mean electron takeoff angle: 45\u0026deg; to sample surface normal; Base pressure: 5x10\u003csup\u003e\u0026minus;\u0026thinsp;10\u003c/sup\u003e mbar, Pressure during measurements: \u0026lt;1 x 10\u003csup\u003e\u0026minus;\u0026thinsp;8\u003c/sup\u003e mbar). Samples were mounted on non-conductive tape. A combination of electronic and ionic charge compensation was used for all measurements (automatized as provided by PHI). Surface cleaning was performed by using a PHI Gas Cluster Ion Gun (GCIB) (5 kV for 300 s). Spectral analysis was carried out using CasaXPS, with corrections for instrument transmission and background removal via the Shirley background [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e] and sensitivity factors provided by PHI [\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e]. Deconvolution of spectra was carried out by using a Voigtian lineshape if not stated otherwise. All content values shown are in units of relative atomic percent (at.-%), where the detection limit in survey measurements usually lies around 0.1\u0026ndash;1 at.- %, depending on the element. Assignment of different components was primarily done using Refs. [\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e], [\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eBesides the powder characterization, Raman spectroscopy was employed to characterize the coatings and wear tracks. Hybrid MXenes wear scars were recorded in three different zones: reference coating, tribolayer and pile-up zone. Both wear scars of MXenes tested separately were recorded in two zones: tribolayer and pile-up zone. Settings used during measurement were: RTD exposure time of 1 s, exposure time of 100 s and Accumulation number of 2. All examined zones were measured without filter using a 50x Fluotar objective.\u003c/p\u003e\u003cp\u003eThe wear tracks were further analysed by scanning electron microscopy (SEM, Zeiss Eco 10, equipped with a tungsten cathode as an electron source) in combination with EDS. A Zeiss SmartEDS detector (silicon drift with a silicon nitride window) was employed for EDS measurements. The excitation energy was 20 kV, and the base system pressure was 1,3 x 10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e mbar and during the measurements 5 x 10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003e mbar.\u003c/p\u003e\u003cp\u003eThe structure of the formed tribofilms was analyzed by transmission electron microscopy (TEM, FEI TECNAI F20). Energy dispersive X-ray spectroscopy (EDS) was performed within the TEM using an EDAX-AMETEK Apollo XLTW SDD system. For TEM, a thin lamella was prepared using a ThermoFisher Scios II Focused Ion Beam (FIB). The lamella measured approximately 20 \u0026times; 10 \u0026micro;m\u0026sup2; with a thickness less than 100 nm thick in the regions of interest. A protective layer of tungsten is deposited to protect the coating during the cutting process. Phase analysis was performed using Selected Area Electron Diffraction (SAED) patterns. In addition, high-resolution TEM (HR-TEM) imaging was used for phase analysis using lattice spacing measurements from the HR-TEM images.\u003c/p\u003e"},{"header":"Results and discussion","content":"\u003cp\u003eStructure and chemical characterization of the used MXenes\u003c/p\u003e\u003cp\u003eThe Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e used in this study was synthesized by in situ HF etching of Ti\u003csub\u003e3\u003c/sub\u003eAlC\u003csub\u003e2\u003c/sub\u003e, while Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e was obtained from Nb\u003csub\u003e2\u003c/sub\u003eAlC\u003csub\u003e2\u003c/sub\u003e. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e (a) and (b) show the multi-layered flake structures imaged by scanning electron microscopy (SEM). Further details on the layered structure were revealed by transmission electron microscopy (TEM). Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e (c) shows a single flake of the TEM image of a Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e revealing an interlayer spacing in the z-direction of 1.04\u0026thinsp;\u0026plusmn;\u0026thinsp;0.29 nm and 0.92\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37 nm for Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e, (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e, Supporting Information), which corresponds to the values reported in literature [\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e]. The TEM image of a Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e flake is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e (c). A selected area diffraction pattern was recorded of position 1 Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e (c1)) confirms a crystalline structure, which could be identified as Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003e in zone axis (ZA) [441]. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e (d) and a larger magnification in (d1) shows the layered structure of the material with interlayer spacing of 1.28 nm (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e (c), Supporting Information). A TEM image of a Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e flake is presented Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e (e), with corresponding SAED pattern of position 2, (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e (e1), confirming the crystalline structure of Nb\u003csub\u003e2\u003c/sub\u003eC in ZA [001]. High resolution TEM images of the structure are shown in (f) and enlarged (f1).\u003c/p\u003e\u003cp\u003eThe phase purity and structural characteristics of the synthesized MXene powder were confirmed by powder X-ray diffraction (Figure S2 (a), Supporting Information). The diffraction pattern displayed a sharp and intense (002) peak at low angles, characteristic of well-ordered MXene layers with increased interlayer spacing, indicating successful etching and delamination of the MAX phase. The absence of residual MAX phase reflections further confirms the high purity of the final product.\u003c/p\u003e\u003cp\u003eFigure S2 (b), Supporting Information illustrates the Raman spectra for two MXenes: Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e (black) and Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e (red). The Ti-MXenes show typical peak at 207cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e corresponding to an out of the plane Ti-C vibration A\u003csub\u003e1g\u003c/sub\u003e. Peak at 374 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e indicates vibrations coming from the surface terminal groups of MXene, while peak at 626 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e indicates carbon vibrations. Two peaks D and G, coming from carbon vibrations are located at around 1380 and 1546 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Small peak at 160 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e indicates Ti-O bond vibration [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe Nb-MXene Raman spectrum shows peaks which are in good agreement with those reported in literature. The peaks at 133 and 267 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e represent in-plane and out-of-plane Nb vibrations (Nb\u0026ndash;O), respectively. Peaks detected at 251, 435 and 639 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e represent OH, F and O surface termination vibrations, respectively. D and G carbon peaks are present at around 1363 and 1600 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e [\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFrictional performance of MXenes\u003c/p\u003e\u003cp\u003eThe tribological performance of the different MXene coated samples was evaluated using a ball-on-disk tribometer operating in linear sliding mode. Coefficient of friction (COF) values were recorded for Ti₃C₂Tx, Nb₂CTx and their hybrid coating in contact with a Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e counterbody, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e (a). Their frictional behaviour is compared to that of an uncoated steel reference sample, tested without any lubrication.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eIn the case of the uncoated steel sample against the Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e counterbody, the typical behaviour under dry sliding conditions with a ceramic counterpart is observed, with noticeable fluctuations during the running-in phase and a rapid increase in the COF, regardless of the test conditions [\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e]. More specifically, the initial COF for the steel reference (steel REF), is approximately 0.25, which quickly increases to almost 0.7 within the first 400 s, after which a steady state value of around 0.8 is reached. The observed friction behaviour corresponds to the typical running-in phase of dry, uncoated metal-ceramic contact under ambient conditions. The significant increase and variability in the COF are primarily attributed to the progressive removal of microscopic surface roughness caused by abrasion and shear at the contact interface [\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e]. Additionally, ongoing mechanical wear and material transformation generate wear debris, which further contributes to fluctuations and variations in the COF [\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn contrast, the Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e coated sample held the COF to 0.2 in the first 200 seconds, to then rapidly diverge to 0.8. The evolution in time of the COF for the Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e coating reveals a different trend. The COF started at 0.17, followed by a gradual increase to around 0.5, where it remained stable until around 1200 seconds before further rising to 0.8. Compared to the reference and Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e, the Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e coating showed a larger standard deviation, indicating greater variability in friction behaviour.\u003c/p\u003e\u003cp\u003eA possible interpretation of the COF vs time curve suggests that under the applied tribological conditions, the contact pressure of 0.48 GPa led to the removal of the MXene coatings from the contact zone, resulting in material accumulation at the turning points of the wear track. This detachment facilitated the formation of debris and oxides, which acted as abrasives and contributed to the observed increase in COF.\u003c/p\u003e\u003cp\u003eA significant reduction and stability in time of the COF was observed for the hybrid coating. Starting at 0.14, the friction reduction remains consistent and stable throughout the entire test duration, without noticeable fluctuations. By the end of the test, the COF stabilizes at 0.17, demonstrating that the hybrid coating retains its beneficial friction-reducing effects. The results surpass the previous tests, with the hybrid coating achieving 82% reduction in COF with respect to the references.\u003c/p\u003e\u003cp\u003ePanels (b), (c), and (d) of Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e present the wear track morphologies after the tribological tests for Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e, Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e and the hybrid coating respectively. The wear track morphology of the hybrid coating differs significantly from those of the individual MXene coatings. For the hybrid coating (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e (d)), a tribofilm formed by dark patchy traces is observed. In contrast, the wear tracks of the individual MXene coatings (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e (b) and (c)) show an uneven film formation, particularly at the track edges and reversal points. Surface analytics is required to clarify the underlying tribological mechanism. To this goal, we carried out various post-test analyses of the substrate surfaces after the friction test. To gain insight into the chemical and structural properties, the results of XPS, Raman, and TEM as well as TEM-EDS analysis are presented in the following sections. Since the most promising behaviour was observed on the hybrid coating, our analysis focuses primarily on this coating.\u003c/p\u003e\u003cp\u003eSurface analysis of the wear tracks.\u003c/p\u003e\u003cp\u003eSEM EDS analysis was carried out on different regions of the wear tracks. For the Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e coated sample, no detectable Ti was found in the central region of the wear track (area 4, Figure S4 (a), Supporting Information), whereas a small amount of detectable Nb was identified in the corresponding region of the Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e coated sample (area 4, Figure S4 (b), Supporting Information). These results suggest that both Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e and Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e were pushed away from the contact zone and accumulated at the edges, indicating partial coating failure due to lack of adhesion.\u003c/p\u003e\u003cp\u003eWe applied Raman spectroscopy to characterize the tribofilms found in the obtained wear tracks (see Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The spectra exhibit vibrational modes corresponding to characteristic peaks of MXene powders (see Figure S2 (b), Supporting Information), indicating the chemical stability of the formed tribolayer. In contrast, the pile-up zone reveals a weak Ti-O vibrational mode, which suggests that the MXene is partially oxidised. Additionally, the D and G bands exhibit significantly higher intensity in the pile-up region than the Ti out of-the-plane vibration, indicating an increased carbonaceous contribution. The sharp peak at 659 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e may be due to intensified carbon vibrations or potential contributions from Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e [\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e]; however, the overlap of these two signals makes it difficult to identify the individual contributions precisely.\u003c/p\u003e\u003cp\u003eThe Raman spectrum of Nb-MXene shows the same characteristic peaks as the powder sample, though with altered intensity ratios (Figure S2 (b), Supporting Information). A pronounced peak at 675 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is observed in the tribolayer region, which corresponds to Nb-O bond vibrations. The peak intensity is more dominant than the one found in Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e, suggesting that Nb-based MXene is more prone to oxidation with respect to the Ti counterpart. The results suggest that the tribological test has induced partial chemical instability of the Nb-MXene. In contrast, the pile-up zone exhibits spectral features consistent with those of the original powder, possibly indicating that the MXene flakes that remain in the contact area undergo harsh tribochemical processes, while those able to slide toward the pile-up zone can maintain a less oxidised state.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFinally, Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows the Raman spectra of the hybrid coating evaluated in three points on the surface. The tribolayer (red), the pile-up zone (green), and the untested coating (black). Only Ti-based MXenes were detected in the reference zone of the hybrid coating, with no peaks corresponding to Nb-MXenes vibrations. Notably, no peaks indicating oxidation of MXene were found, suggesting good oxidation stability of the hybrid coating.\u003c/p\u003e\u003cp\u003eThe tribolayer in the hybrid MXenes indicates the presence of both types of MXene due to distinct peaks appearing at 203 and 258 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, representing Ti and Nb vibrations, respectively.\u003c/p\u003e\u003cp\u003eThe relatively low intensity of the D and G bands indicates a reduced degree of carbon disorder within the tribolayer. Additionally, a new vibrational mode observed at 770 cm⁻\u0026sup1;, attributed to the A₁g(C) phonon, emerges in the Raman spectrum. Notably, this feature is absent in both the pristine MXene powders (see Figure S2 (b), Supporting Information) and the singly MXene-coated samples (Figure S3, Supporting Information), which exhibit pronounced carbon-related vibrations but lack the 770 cm⁻\u0026sup1; peak. This distinction suggests that the Raman signature reflects a synergistic effect arising from the hybrid coating, surpassing the characteristics of the single-coated configurations.\u003c/p\u003e\u003cp\u003eSpecifically, the diminished D and G band contributions, coupled with the appearance of the A₁g(C) mode, imply a surface restructuring within the tribolayer. This restructuring likely results in better ordering or exposure of MXene flakes. It is proposed that the kinetic energy imparted during tribological stress facilitates this transformation by reducing carbon disorder and promoting the alignment of MXene flakes at the interface with the counterbody. Analysis of the pile-up zone reveals a weak Nb-O peak, which is also present in the reference powder. This suggests that partially oxidised Nb-MXenes are being ejected from the contact zone into the pile-up zone by the oscillatory motion of the counterbody, while unoxidised particles form a stable tribological film.\u003c/p\u003e\u003cp\u003eX-ray photoelectron spectroscopy (XPS) was conducted on both the as-deposited coating (reference) and the wear track (tribolayer) to further examine the oxidation state of niobium. Specifically, we analysed the C 1s, F 1s, Nb 3d, O 1s, and Ti 2p core levels (see Figure S10, Supporting Information). The tribolayer exhibited a higher concentration of oxides, particularly TiO₂ and Nb₂O₅, compared to the reference surface. Quantitative analysis revealed that the oxide-to-carbide ratio for Nb 3d exceeded unity in both the reference and tribolayer regions, whereas for Ti 2p, this ratio remained below one (see Table S3, Supporting Information).\u003c/p\u003e\u003cp\u003eThese findings suggest that Nb-based MXenes are more susceptible to oxidation under tribological stress, while Ti-based MXenes retain a more carbide-like character. This trend is consistent with the Raman spectroscopy results, which also indicated a higher degree of structural preservation in the Ti-based components.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eTransmission electron microscopy (TEM) Analysis.\u003c/p\u003e\u003cp\u003eTo gain deeper insight into the structure and composition of the tribofilms formed in the MXene hybrid coating, transmission electron microscopy (TEM) was employed to examine the wear track. A focused ion beam (FIB) was used to extract a cross-sectional TEM lamella from the edge region of the hybrid coating, approximately at the centre of the wear track (see Figure S4, Supporting Information). The cross-sectional TEM image reveals a compact, flat tribofilm with an average thickness of approximately 230.5\u0026thinsp;\u0026plusmn;\u0026thinsp;82 nm following tribological testing (Figure S5 (h)-(i), Supporting Information).\u003c/p\u003e\u003cp\u003eTo further investigate the elemental distribution within the tribolayer and assess compositional changes induced by sliding, energy-dispersive X-ray spectroscopy (EDS) mapping was performed. The elemental maps show a relatively uniform distribution of Ti and Nb throughout the tribofilm (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e (a3) and Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e (a4)). Notably, the oxygen signal (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e (a6)) closely follows the Ti distribution, consistent with the presence of oxygen-containing surface terminations on Ti-based MXenes.\u003c/p\u003e\u003cp\u003eInterestingly, the cross-sectional analysis reveals a stratified structure within the tribofilm: Ti-rich regions are predominantly located near the substrate, while Nb-rich regions are concentrated toward the top surface. This stratification does not correspond to the original sequential deposition of the coating layers, suggesting that it results from tribologically induced redistribution during sliding.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eTEM was used to examine the microstructure of two distinct regions within the tribofilm (Zone 1 and Zone 2), and selected area electron diffraction (SAED) patterns were acquired for the evaluation and determination of the crystal phase after the deformation caused by the tribo-tests see Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn Zone 1, TEM images (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e (a2)) reveal that the tribofilm possesses a mixed microstructure. A TEM image with a lager magnification taken at position 1 highlights the layered structure of the MXene flakes (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e (a4)). Figure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e (a3) confirms nanocrystallinity, indicated by the formation from spots to rings. Further, the diffraction patterns show a spread in the radio of the diffraction spots, which is due to a slight but continuously change in the crystal lattice parameters.\u003c/p\u003e\u003cp\u003eIn contrast, the pre-tested MXene flakes shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e (c1) and (e1) indicate a pure single crystal structure. Thus, it can be concluded that this change in the crystal structure is caused by the tribological tests.\u003c/p\u003e\u003cp\u003eIn Zone 1, an amorphous ring is clearly visible in the diffraction pattern. It is stemming from the left and right outer part in the selected area diffraction aperture \u0026ndash; see Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e (a2). The amorphous regions indicate a complete destruction of the crystallinity of the Nb and Ti flakes, caused by the tribological tests. The diffraction pattern shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e (b3) shows the crystalline structure of Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e. More details are available in the Supporting Information (Figure S7 and S8).\u003c/p\u003e\u003cp\u003eMoreover, Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e (b4), shows the area of Zone 2 at higher magnification in a high-resolution TEM image, where crystalline and amorphous regions can be identified immediately.\u003c/p\u003e\u003cp\u003eFor Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e and Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e MXenes (crystal structure confirmed by mean lattice spacing distances) an area named \u0026ldquo;MX\u0026rdquo; is defined, where MXene-layers are visible but not clearly identifiable. Moreover, an amorphous region runs through the centre of the picture. Details on the calculated lattice distances are reported in Figure S9 (Supporting Information). It could not be observed any gap between the different areas, suggesting that the MXene-flakes are compacted together in different configurations after the tribological tests. The diffraction patterns could be clearly identified as the phases Nb\u003csub\u003e2\u003c/sub\u003eC and Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003e, confirming that a part of the tribofilm maintains the initial crystallinity of the unencumbered flakes.\u003c/p\u003e\u003cp\u003eTribological mechanism of Nb-Ti MXene hybrid coating\u003c/p\u003e\u003cp\u003eThe developed hybrid coating shows exceptional COF performances (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), and the surface analytics confirm the presence of both MXenes types in the wear tracks (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e), where they present diverse crystallographic structures (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). Interestingly, the cross-section investigation by TEM-EDS presents a different arrangement of the MXene flakes with respect to the initial application sequence: the hybrid coating is prepared by depositing first the Nb\u003csub\u003e2\u003c/sub\u003eCT\u003csub\u003ex\u003c/sub\u003e solution followed by the Ti\u003csub\u003e3\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eT\u003csub\u003ex\u003c/sub\u003e solution, creating a mixture of the two materials which could not be confirmed after the tribological test.\u003c/p\u003e\u003cp\u003eHereby we propose an adaptive reconfiguration as a possible tribological mechanism. Upon the onset of tribological stress, the system self-organizes into a configuration that minimizes friction and wear. Thus, Ti₃C₂Tₓ, which has a better chemical affinity to the substrate with respect to Nb₂CTₓ due to the stable Ti-Fe interfacial bonding, is displaced at the substrate interface, forming a stable and adherent layer. Consequently, the sliding interface transitions to one dominated by Nb₂CTₓ vs. Ti₃C₂Tₓ flake interactions, which lowers the COF due to interlayer shearing between the MXenes species.\u003c/p\u003e\u003cp\u003eNotably, Raman spectroscopy indicates that the pile-up zone is predominantly composed of oxidised Nb₂CTₓ, confirming that in this adaptive configuration, Nb-based MXenes migrate to the counterbody interface and are subsequently transported out of the contact zone. However, due to the poor chemical stability of Nb₂CTₓ, it collapses to its oxidised form as showed by XPS. Both TEM and Raman spectroscopy highlight the significant role of carbon: Raman reveals distinct differences in carbon vibrational modes between the wear track and the pile-up zone (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e), while TEM shows amorphous regions (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e) and TEM-EDS a broad distribution of carbon within the wear track (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). Additionally, XPS analysis indicates that Ti₃C₂Tₓ retains its carbide nature even after tribological stress, rather than converting to an oxide.\u003c/p\u003e\u003cp\u003eIn summary, under tribological stress, the hybrid coating undergoes a dynamic reorganization that leverages the distinct properties of its components. The Nb₂CTₓ phase, owing to its high tribochemical reactivity, contributes to the formation of an initial sacrificial surface layer. Meanwhile, the Ti₃C₂Tₓ phase, thanks to the strong mechanical stability and the better chemical affinity to the substrate, sustains a low COF by forming a robust layer on which Nb₂CTₓ can slide. Importantly, Nb₂CTₓ is not entirely consumed in the sacrificial process; it remains active within the wear track and continues to facilitate sliding in conjunction with Ti₃C₂Tₓ. This stress-induced redistribution results in a synergistic interaction between the two MXenes, enabling superior tribological performance that neither material achieves on its own, as demonstrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study presented a systematic investigation into the tribological behaviour of MXene hybrid coatings (Nb₂CTₓ and Ti₃C₂Tₓ) under dry sliding conditions. Through a multi-technique characterization approach including SEM-EDS, Raman spectroscopy, XPS, and TEM, we demonstrate that the hybrid MXene coating significantly outperforms the individual components in terms of friction reduction and wear resistance.\u003c/p\u003e\u003cp\u003eThe hybrid coating exhibits a stable and low coefficient of friction (COF\u0026thinsp;\u0026lt;\u0026thinsp;0.2), attributed to the formation of a compact, patchy tribofilm. The low and stable COF found at the selected contact pressure (0.48 GPa) makes the hybrid coating competitive in the framework of different solid lubricants (see the list in Table S2). These performances are attributed to the tribofilm forming from a stress-induced adaptive reconfiguration, wherein Ti₃C₂Tₓ preferentially anchors to the substrate due to its superior interfacial bonding, while Nb₂CTₓ migrates toward the sliding interface, acting as a sacrificial layer. This dynamic redistribution results in a stratified tribolayer with enhanced mechanical integrity and tribochemical resilience.\u003c/p\u003e\u003cp\u003eRaman and XPS analyses confirm that within the hybrid tribofilm, Ti₃C₂Tₓ retains its carbide nature under tribological stress, while Nb₂CTₓ undergoes partial oxidation, contributing to the formation of a lubricious oxide-rich surface. TEM imaging reveals a nanostructured tribofilm with both crystalline and amorphous domains, further supporting the hypothesis of synergistic interaction between the two MXenes.\u003c/p\u003e\u003cp\u003eThese findings highlight the potential of hybrid MXenes as a powerful strategy for designing next-generation solid lubricants. By leveraging the complementary properties of different MXene species, it is possible to engineer coatings with tailored tribological performance, opening new avenues for advanced applications in energy-efficient and high-performance mechanical systems.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eAcknowledgements\u003c/p\u003e\n\u003cp\u003eThe authors thank Ms. Bianca Aigner and AC2T Research GmbH for providing access to laboratory equipment and for their valuable support in the preparation of the coatings.\u003c/p\u003e\n\u003cp\u003eFunding\u003c/p\u003e\n\u003cp\u003eThe authors gratefully acknowledge the Austrian Research Promotion Agency (FFG) for funding the infrastructure \u0026ldquo;ELSA\u0026rdquo; under grant number 884672. We further acknowledge FFG for funding within the LASER2D project. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eWe also thank the TU Wien Library for its financial support through the Open Access Publishing Fund.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePart of this work was carried out as part of the COMET Centre InTribology (FFG no. 906860), a project of the \u0026ldquo;Excellence Centre for Tribology\u0026rdquo; (AC2T research GmbH). In Tribology is funded within the COMET \u0026ndash; Competence Centres for Excellent Technologies Programme by the federal ministries BMIMI and BMWET as well as the federal states of Nieder\u0026ouml;sterreich and Vorarlberg based on financial support from the project partners involved. COMET is managed by The Austrian Research Promotion Agency (FFG).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe authors acknowledge \u0026rdquo;Gesellschaft f\u0026uuml;r Forschungsf\u0026ouml;rderung Nieder\u0026ouml;sterreich m.b.H.\u0026rdquo; through its FTI PhD Funding Programme (FTI22‐D‐018).\u003c/p\u003e\n\u003cp id=\"_Toc206775683\"\u003eAuthor contributions\u003c/p\u003e\n\u003cp\u003eChristina Danecker: Experiments, Analyzation, Characterizations, first draft, Writing\u003c/p\u003e\n\u003cp\u003eSabine Schwarz: FIB / TEM measurements\u003c/p\u003e\n\u003cp\u003eMarko Piljevic: Raman, Writing\u003c/p\u003e\n\u003cp\u003eJakob Rath: XPS measurements\u003c/p\u003e\n\u003cp\u003eMartin Nastran, Bernhard Bayer-Skoff: XRD measurements\u003c/p\u003e\n\u003cp\u003eMichael Naguib, Ahmad Majed, Karamullah Eisawi: MXene synthesis, writing\u003c/p\u003e\n\u003cp\u003ePierluigi Bilotto: Supervision, Writing\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCarsten Gachot: Supervision, Writing\u003c/p\u003e\n\u003cp id=\"_Toc206775684\"\u003eData availability statement\u003c/p\u003e\n\u003cp\u003eData will be available upon sensible request\u003c/p\u003e\n\u003cp id=\"_Toc206775685\"\u003eCompeting interests\u003c/p\u003e\n\u003cp\u003eNo competing interests to declare\u003c/p\u003e\n\u003cp id=\"_Toc206775686\"\u003eAdditional information (Correspondence)\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003e\u0026bdquo;Energy Technology Perspectives 2020 \u0026ndash; Analysis, IEA. Zugegriffen: 21. M\u0026auml;rz 2025. [Online]. Verf\u0026uuml;gbar unter: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.iea.org/reports/energy-technology-perspectives-2020\u003c/span\u003e\u003cspan address=\"https://www.iea.org/reports/energy-technology-perspectives-2020\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHolmberg, K. \u0026amp; Erdemir, A. \u0026bdquo;Influence of tribology on global energy consumption, costs and emissions, \u003cem\u003eFriction\u003c/em\u003e, Bd. 5, Nr. 3, S. 263\u0026ndash;284, Sep. (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s40544-017-0183-5\u003c/span\u003e\u003cspan address=\"10.1007/s40544-017-0183-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWang, H. et al. \u0026bdquo;Tribological Behavior of NiAl-Layered Double Hydroxide Nanoplatelets as Oil-Based Lubricant Additives, \u003cem\u003eACS Appl. Mater. Interfaces\u003c/em\u003e, Bd. 9, Nr. 36, S. 30891\u0026ndash;30899, Sep. (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1021/acsami.7b10515\u003c/span\u003e\u003cspan address=\"10.1021/acsami.7b10515\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNaguib, M., Mochalin, V. N., Barsoum, M. W. \u0026amp; Gogotsi, Y. \u0026bdquo;25th Anniversary Article: MXenes: A New Family of Two-Dimensional Materials. \u003cem\u003eAdv. Mater.\u003c/em\u003e \u003cb\u003eBd. 26\u003c/b\u003e (Nr. 7), 992\u0026ndash;1005. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/adma.201304138\u003c/span\u003e\u003cspan address=\"10.1002/adma.201304138\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2014).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eReeves, C. J., Siddaiah, A. \u0026amp; Menezes, P. L. \u0026bdquo;A Review on the Science and Technology of Natural and Synthetic Biolubricants, \u003cem\u003eJ. Bio- Tribo-Corros.\u003c/em\u003e, Bd. 3, Nr. 1, S. 11, Jan. (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s40735-016-0069-5\u003c/span\u003e\u003cspan address=\"10.1007/s40735-016-0069-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLugt, P. M. \u0026bdquo;A Review on Grease Lubrication in Rolling Bearings. \u003cem\u003eTribol Trans.\u003c/em\u003e \u003cb\u003eBd. 52\u003c/b\u003e (Nr. 4), 470\u0026ndash;480. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1080/10402000802687940\u003c/span\u003e\u003cspan address=\"10.1080/10402000802687940\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (Juni 2009).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCai, M., Zhao, Z., Liang, Y., Zhou, F. \u0026amp; Liu, W. \u0026bdquo;Alkyl Imidazolium Ionic Liquids as Friction Reduction and Anti-Wear Additive in Polyurea Grease for Steel/Steel Contacts. \u003cem\u003eTribol Lett.\u003c/em\u003e \u003cb\u003eBd. 40\u003c/b\u003e (Nr. 2), 215\u0026ndash;224. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s11249-010-9624-2\u003c/span\u003e\u003cspan address=\"10.1007/s11249-010-9624-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (Nov. 2010).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRosenkranz, A. \u0026bdquo;Multi-layer Ti3C2Tx-nanoparticles (MXenes) as solid lubricants \u0026ndash; Role of surface terminations and intercalated water. \u003cem\u003eAppl. Surf. Sci.\u003c/em\u003e \u003cb\u003eBd. 494\u003c/b\u003e, 13\u0026ndash;21. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.apsusc.2019.07.171\u003c/span\u003e\u003cspan address=\"10.1016/j.apsusc.2019.07.171\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (Nov. 2019).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eD. Akinwande \u003cem\u003eu. a.\u003c/em\u003e, \u0026bdquo;A review on mechanics and mechanical properties of 2D materials\u0026mdash;Graphene and beyond. \u003cem\u003eExtreme Mech. Lett\u003c/em\u003e, Bd. \u003cb\u003e13\u003c/b\u003e, S. 42\u0026ndash;77, Mai (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.eml.2017.01.008\u003c/span\u003e\u003cspan address=\"10.1016/j.eml.2017.01.008\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eS. B. Mitta \u003cem\u003eu. a.\u003c/em\u003e, \u0026bdquo;Electrical characterization of 2D materials-based field-effect transistors, \u003cem\u003e2D Mater.\u003c/em\u003e, Bd. 8, Nr. 1, S. 012002, Nov. (2020). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1088/2053-1583/abc187\u003c/span\u003e\u003cspan address=\"10.1088/2053-1583/abc187\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhang, S., Ma, T., Erdemir, A. \u0026amp; Li, Q. \u0026bdquo;Tribology of two-dimensional materials: From mechanisms to modulating strategies. \u003cem\u003eMater. Today\u003c/em\u003e. \u003cb\u003eBd. 26\u003c/b\u003e, 67\u0026ndash;86. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.mattod.2018.12.002\u003c/span\u003e\u003cspan address=\"10.1016/j.mattod.2018.12.002\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (Juni 2019).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLian, W., Mai, Y., Liu, C., Zhang, L. \u0026amp; Li, S. Jie, \u0026bdquo;Two-dimensional Ti3C2 coating as an emerging protective solid-lubricant for tribology. \u003cem\u003eCeram. Int.\u003c/em\u003e \u003cb\u003eBd. 44\u003c/b\u003e, 20154\u0026ndash;20162. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.ceramint.2018.07.309\u003c/span\u003e\u003cspan address=\"10.1016/j.ceramint.2018.07.309\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (Nov. 2018).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWu, F. B., Zhou, S. J., Ouyang, J. H., Wang, S. Q. \u0026amp; Chen, L. \u0026bdquo;Structural Superlubricity of Two-Dimensional Materials: Mechanisms, Properties, Influencing Factors, and Applications, \u003cem\u003eLubricants\u003c/em\u003e, Bd. 12, Nr. 4, Art. Nr. 4, Apr. (2024). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3390/lubricants12040138\u003c/span\u003e\u003cspan address=\"10.3390/lubricants12040138\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eM. Naguib \u003cem\u003eu. a.\u003c/em\u003e, \u0026bdquo;Two-Dimensional Nanocrystals Produced by Exfoliation of Ti3AlC2. \u003cem\u003eAdv Mater\u003c/em\u003e, Bd. \u003cb\u003e23\u003c/b\u003e, Nr. 37, S. 4248\u0026ndash;4253, (2011). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/adma.201102306\u003c/span\u003e\u003cspan address=\"10.1002/adma.201102306\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSokol, M., Natu, V., Kota, S. \u0026amp; Barsoum, M. W. \u0026bdquo;On the Chemical Diversity of the MAX Phases, \u003cem\u003eTrends Chem.\u003c/em\u003e, Bd. 1, Nr. 2, S. 210\u0026ndash;223, Mai (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.trechm.2019.02.016\u003c/span\u003e\u003cspan address=\"10.1016/j.trechm.2019.02.016\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNaguib, M., Barsoum, M. W. \u0026amp; Gogotsi, Y. \u0026bdquo;Ten Years of Progress in the Synthesis and Development of MXenes. \u003cem\u003eAdv. Mater.\u003c/em\u003e \u003cb\u003eBd. 33\u003c/b\u003e, 2103393. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/adma.202103393\u003c/span\u003e\u003cspan address=\"10.1002/adma.202103393\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2021).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eM. Ostermann \u003cem\u003eu. a.\u003c/em\u003e, \u0026bdquo;Pulsed Electrochemical Exfoliation for an HF-Free Sustainable MXene Synthesis, \u003cem\u003eSmall\u003c/em\u003e, Bd. 21, Nr. 22, S. 2500807, (2025). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/smll.202500807\u003c/span\u003e\u003cspan address=\"10.1002/smll.202500807\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHantanasirisakul, K. \u0026amp; Gogotsi, Y. \u0026bdquo;Electronic and Optical Properties of 2D Transition Metal Carbides and Nitrides (MXenes). \u003cem\u003eAdv. Mater.\u003c/em\u003e \u003cb\u003eBd. 30\u003c/b\u003e, 1804779. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/adma.201804779\u003c/span\u003e\u003cspan address=\"10.1002/adma.201804779\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2018).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGao, G., O\u0026rsquo;Mullane, A. P. \u0026amp; Du, A. \u0026bdquo;2D MXenes: A New Family of Promising Catalysts for the Hydrogen Evolution Reaction. \u003cem\u003eACS Catal.\u003c/em\u003e \u003cb\u003eBd. 7\u003c/b\u003e (Nr. 1), 494\u0026ndash;500. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1021/acscatal.6b02754\u003c/span\u003e\u003cspan address=\"10.1021/acscatal.6b02754\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (Jan. 2017).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMojtabavi, M., VahidMohammadi, A., Liang, W. \u0026amp; Beidaghi, M. M\u0026auml;rz, und M. Wanunu, \u0026bdquo;Single-Molecule Sensing Using Nanopores in Two-Dimensional Transition Metal Carbide (MXene) Membranes, \u003cem\u003eACS Nano\u003c/em\u003e, Bd. \u003cb\u003e13\u003c/b\u003e, Nr. 3, S. 3042\u0026ndash;3053, (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1021/acsnano.8b08017\u003c/span\u003e\u003cspan address=\"10.1021/acsnano.8b08017\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi, Z. et al. \u0026bdquo;Surface Nanopore Engineering of 2D MXenes for Targeted and Synergistic Multitherapies of Hepatocellular Carcinoma. \u003cem\u003eAdv. Mater.\u003c/em\u003e \u003cb\u003eBd. 30\u003c/b\u003e, 1706981. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/adma.201706981\u003c/span\u003e\u003cspan address=\"10.1002/adma.201706981\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2018). Nr. 25.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSundaram, A. \u0026bdquo;Engineering of 2D transition metal carbides and nitrides MXenes for cancer therapeutics and diagnostics. \u003cem\u003eJ. Mater. Chem. B\u003c/em\u003e. \u003cb\u003eBd. 8\u003c/b\u003e, 4990\u0026ndash;5013. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1039/D0TB00251H\u003c/span\u003e\u003cspan address=\"10.1039/D0TB00251H\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (Juni 2020).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eM. R. Lukatskaya \u003cem\u003eu. a.\u003c/em\u003e, \u0026bdquo;Ultra-high-rate pseudocapacitive energy storage in two-dimensional transition metal carbides. \u003cem\u003eNat Energy\u003c/em\u003e, Bd. \u003cb\u003e6\u003c/b\u003e, (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/nenergy.2017.105\u003c/span\u003e\u003cspan address=\"10.1038/nenergy.2017.105\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eXing, C. \u0026bdquo;Two-Dimensional MXene (Ti3C2)-Integrated Cellulose Hydrogels: Toward Smart Three-Dimensional Network Nanoplatforms Exhibiting Light-Induced Swelling and Bimodal Photothermal/Chemotherapy Anticancer Activity. \u003cem\u003eACS Appl. Mater. Interfaces\u003c/em\u003e. \u003cb\u003eBd. 10\u003c/b\u003e, 27631\u0026ndash;27643. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1021/acsami.8b08314\u003c/span\u003e\u003cspan address=\"10.1021/acsami.8b08314\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2018).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRasool, K. et al. \u0026bdquo;Antibacterial Activity of Ti3C2Tx MXene. \u003cem\u003eACS Nano\u003c/em\u003e. \u003cb\u003eBd. 10\u003c/b\u003e (Nr. 3), 3674\u0026ndash;3684. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1021/acsnano.6b00181\u003c/span\u003e\u003cspan address=\"10.1021/acsnano.6b00181\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (M\u0026auml;rz 2016).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eS. Luo \u003cem\u003eu. a.\u003c/em\u003e, \u0026bdquo;Tensile behaviors of Ti3C2Tx (MXene) films, \u003cem\u003eNanotechnology\u003c/em\u003e, Bd. 31, Nr. 39, S. 395704, Juli (2020). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1088/1361-6528/ab94dd\u003c/span\u003e\u003cspan address=\"10.1088/1361-6528/ab94dd\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRosenkranz, A., Righi, M. C., Sumant, A. V., Anasori, B. \u0026amp; Mochalin, V. N. \u0026bdquo;Perspectives of 2D MXene Tribology. \u003cem\u003eAdv. Mater.\u003c/em\u003e \u003cb\u003eBd. 35\u003c/b\u003e (Nr. 5), 2207757. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/adma.202207757\u003c/span\u003e\u003cspan address=\"10.1002/adma.202207757\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2023).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMarian, M. \u0026bdquo;Mxene nanosheets as an emerging solid lubricant for machine elements \u0026ndash; Towards increased energy efficiency and service life. \u003cem\u003eAppl. Surf. Sci.\u003c/em\u003e \u003cb\u003eBd. 523\u003c/b\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.apsusc.2020.146503\u003c/span\u003e\u003cspan address=\"10.1016/j.apsusc.2020.146503\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2020).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWyatt, B. C., Rosenkranz, A. \u0026amp; Anasori, B. \u0026bdquo;2D MXenes: Tunable Mechanical and Tribological Properties. \u003cem\u003eAdv. Mater.\u003c/em\u003e \u003cb\u003eBd. 33\u003c/b\u003e, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/adma.202007973\u003c/span\u003e\u003cspan address=\"10.1002/adma.202007973\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2021). Nr. 17, S. 2007973.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFeng, Q. et al. \u0026bdquo;Enhancing the tribological performance of Ti3C2 MXene modified with tetradecylphosphonic acid. \u003cem\u003eColloids Surf. Physicochem Eng. Asp\u003c/em\u003e. \u003cb\u003eBd. 625\u003c/b\u003e, 126903. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.colsurfa.2021.126903\u003c/span\u003e\u003cspan address=\"10.1016/j.colsurfa.2021.126903\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (Sep. 2021).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eP. G. Gr\u0026uuml;tzmacher \u003cem\u003eu. a.\u003c/em\u003e, \u0026bdquo;Superior Wear-Resistance of Ti3C2Tx Multilayer Coatings, \u003cem\u003eACS Nano\u003c/em\u003e, Bd. 15, Nr. 5, S. 8216\u0026ndash;8224, Mai (2021). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1021/acsnano.1c01555\u003c/span\u003e\u003cspan address=\"10.1021/acsnano.1c01555\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBoidi, G. \u0026bdquo;Influence of \u003cem\u003eex-situ\u003c/em\u003e annealing on the friction and wear performance of multi-layer Ti3C2T\u003cem\u003ex\u003c/em\u003e coatings. \u003cem\u003eAppl. Mater. Today\u003c/em\u003e. \u003cb\u003eBd. 36\u003c/b\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.apmt.2023.102020\u003c/span\u003e\u003cspan address=\"10.1016/j.apmt.2023.102020\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2024). S. 102020, Feb.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNaguib, M. et al. \u0026bdquo;New Two-Dimensional Niobium and Vanadium Carbides as Promising Materials for Li-Ion Batteries, \u003cem\u003eJ. Am. Chem. Soc.\u003c/em\u003e, Bd. 135, Nr. 43, S. 15966\u0026ndash;15969, Okt. (2013). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1021/ja405735d\u003c/span\u003e\u003cspan address=\"10.1021/ja405735d\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePonnalagar, D., Hang, D. R., Islam, S. E., Liang, C. T. \u0026amp; Chou, M. M. C. \u0026bdquo;Recent progress in two-dimensional Nb2C MXene for applications in energy storage and conversion. \u003cem\u003eMater. Des.\u003c/em\u003e \u003cb\u003eBd. 231\u003c/b\u003e, 112046. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.matdes.2023.112046\u003c/span\u003e\u003cspan address=\"10.1016/j.matdes.2023.112046\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (Juli 2023).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNasrin, K., Sudharshan, V., Arunkumar, M. \u0026amp; Sathish, M. \u0026bdquo;2D/2D Nanoarchitectured Nb2C/Ti3C2 MXene Heterointerface for High-Energy Supercapacitors with Sustainable Life Cycle. \u003cem\u003eACS Appl. Mater. Interfaces\u003c/em\u003e. \u003cb\u003eBd. 14\u003c/b\u003e, 21038\u0026ndash;21049. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1021/acsami.2c02871\u003c/span\u003e\u003cspan address=\"10.1021/acsami.2c02871\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (Mai 2022).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBi, M., Miao, Y., Li, W. \u0026amp; Yao, J. \u0026bdquo;Niobium carbide MXene-optics fiber-sensor for high sensitivity humidity detection, \u003cem\u003eAppl. Phys. Lett.\u003c/em\u003e, Bd. 120, Nr. 2, S. 021103, Jan. (2022). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1063/5.0064005\u003c/span\u003e\u003cspan address=\"10.1063/5.0064005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJ. Yin \u003cem\u003eu. a.\u003c/em\u003e, \u0026bdquo;Nb2C MXene-Functionalized Scaffolds Enables Osteosarcoma Phototherapy and Angiogenesis/Osteogenesis of Bone Defects. \u003cem\u003eNano-Micro Lett\u003c/em\u003e, Bd. \u003cb\u003e13\u003c/b\u003e, Nr. 1, S. 30, Jan. (2021). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s40820-020-00547-6\u003c/span\u003e\u003cspan address=\"10.1007/s40820-020-00547-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhou, X., Guo, Y., Wang, D. \u0026amp; Xu, Q. \u0026bdquo;Nano friction and adhesion properties on Ti3C2 and Nb2C MXene studied by AFM. \u003cem\u003eTribol Int.\u003c/em\u003e \u003cb\u003eBd. 153\u003c/b\u003e, 106646. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.triboint.2020.106646\u003c/span\u003e\u003cspan address=\"10.1016/j.triboint.2020.106646\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (Jan. 2021).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCheng, H. \u0026amp; Zhao, W. \u0026bdquo;Regulating the Nb2C nanosheets with different degrees of oxidation in water lubricated sliding toward an excellent tribological performance, \u003cem\u003eFriction\u003c/em\u003e, Bd. 10, Nr. 3, S. 398\u0026ndash;410, M\u0026auml;rz (2022). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s40544-020-0469-x\u003c/span\u003e\u003cspan address=\"10.1007/s40544-020-0469-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChhattal, M. \u0026bdquo;Unveiling the tribological potential of MXenes-current understanding and future perspectives. \u003cem\u003eAdv. Colloid Interface Sci.\u003c/em\u003e \u003cb\u003eBd. 321\u003c/b\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.cis.2023.103021\u003c/span\u003e\u003cspan address=\"10.1016/j.cis.2023.103021\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2023). S. 103021, Nov.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMarquis, E., Cutini, M., Anasori, B., Rosenkranz, A. \u0026amp; Righi, M. C. \u0026bdquo;Nanoscale MXene Interlayer and Substrate Adhesion for Lubrication: A Density Functional Theory Study, \u003cem\u003eACS Appl. Nano Mater.\u003c/em\u003e, Bd. 5, Nr. 8, S. 10516\u0026ndash;10527, Aug. (2022). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1021/acsanm.2c01847\u003c/span\u003e\u003cspan address=\"10.1021/acsanm.2c01847\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eM. Piljević \u003cem\u003eu. a.\u003c/em\u003e, \u0026bdquo;Evaluation of O-terminated sustainable EC-MXene as solid lubricant, 28. \u003cem\u003eChemRxiv\u003c/em\u003e. Mai (2025). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.26434/chemrxiv-2025-tzhc7\u003c/span\u003e\u003cspan address=\"10.26434/chemrxiv-2025-tzhc7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHabib, T. et al. \u0026bdquo;Oxidation stability of Ti3C2Tx MXene nanosheets in solvents and composite films, \u003cem\u003eNpj 2D Mater. Appl.\u003c/em\u003e, Bd. 3, Nr. 1, S. 1\u0026ndash;6, Feb. (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/s41699-019-0089-3\u003c/span\u003e\u003cspan address=\"10.1038/s41699-019-0089-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMarian, M. \u0026bdquo;Effective usage of 2D MXene nanosheets as solid lubricant \u0026ndash; Influence of contact pressure and relative humidity. \u003cem\u003eAppl. Surf. Sci.\u003c/em\u003e \u003cb\u003eBd. 531\u003c/b\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.apsusc.2020.147311\u003c/span\u003e\u003cspan address=\"10.1016/j.apsusc.2020.147311\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2020). S. 147311, Nov.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJ. Simon \u003cem\u003eu. a.\u003c/em\u003e, \u0026bdquo;Tailoring optical response of MXene thin films. \u003cem\u003eNanophotonics Apr\u003c/em\u003e (2025). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1515/nanoph-2024-0769\u003c/span\u003e\u003cspan address=\"10.1515/nanoph-2024-0769\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003e158295, S. \u0026amp; Dez Zambrano-Mera \u003cem\u003eu. a.\u003c/em\u003e, \u0026bdquo;Solid lubrication performance of sandwich Ti3C2Tx-MoS2 composite coatings. \u003cem\u003eAppl. Surf. Sci.\u003c/em\u003e \u003cb\u003eBd. 640\u003c/b\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.apsusc.2023.158295\u003c/span\u003e\u003cspan address=\"10.1016/j.apsusc.2023.158295\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2023).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShirley, D. A. \u0026bdquo;High-resolution x-ray photoemission spectrum of the valence bands of gold, \u003cem\u003ePhys. Rev. B\u003c/em\u003e, Bd. 5, Nr. 12, S. 4709\u0026ndash;4714, (1972). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1103/PhysRevB.5.4709\u003c/span\u003e\u003cspan address=\"10.1103/PhysRevB.5.4709\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eScofield, J. H. \u0026bdquo;Hartree-Slater subshell photoionization cross-sections at 1254 and 1487 eV. \u003cem\u003eJ. Electron. Spectrosc. Relat. Phenom.\u003c/em\u003e \u003cb\u003eBd. 8\u003c/b\u003e (Nr. 2), 129\u0026ndash;137. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/0368-2048(76)80015-1\u003c/span\u003e\u003cspan address=\"10.1016/0368-2048(76)80015-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (Jan. 1976).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003e\u0026bdquo;More Molybdenum Values. Zugegriffen: 8. Mai 2025. [Online]. Verf\u0026uuml;gbar unter: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://www.xpsfitting.com/2014/05/more-molybdenum-values.html\u003c/span\u003e\u003cspan address=\"http://www.xpsfitting.com/2014/05/more-molybdenum-values.html\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBeamson, G. \u0026amp; Briggs, D. R. \u0026bdquo;High Resolution XPS of Organic Polymers: The Scienta ESCA300 Database, 1992. [Online]. Verf\u0026uuml;gbar unter: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://api.semanticscholar.org/CorpusID:92946956\u003c/span\u003e\u003cspan address=\"https://api.semanticscholar.org/CorpusID:92946956\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLiu, Y., Zhang, X., Dong, S., Ye, Z. \u0026amp; Wei, Y. \u0026bdquo;Synthesis and tribological property of Ti3C2TXnanosheets. \u003cem\u003eJ. Mater. Sci.\u003c/em\u003e \u003cb\u003eBd. 52\u003c/b\u003e (Nr. 4), 2200\u0026ndash;2209. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s10853-016-0509-0\u003c/span\u003e\u003cspan address=\"10.1007/s10853-016-0509-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (Feb. 2017).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eA. N. Giordano \u003cem\u003eu. a.\u003c/em\u003e, \u0026bdquo;Raman Spectroscopy and Laser-Induced Surface Modification of Nb2CTx MXene, \u003cem\u003eACS Mater. Lett.\u003c/em\u003e, Bd. 6, Nr. 8, S. 3264\u0026ndash;3271, Aug. (2024). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1021/acsmaterialslett.4c00922\u003c/span\u003e\u003cspan address=\"10.1021/acsmaterialslett.4c00922\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBlau, P. J. \u0026bdquo;On the nature of running-in, \u003cem\u003eTribol. Int.\u003c/em\u003e, Bd. 38, Nr. 11, S. 1007\u0026ndash;1012, Nov. (2005). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.triboint.2005.07.020\u003c/span\u003e\u003cspan address=\"10.1016/j.triboint.2005.07.020\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eM. Chhattal \u003cem\u003eu. a.\u003c/em\u003e, \u0026bdquo;Solid lubrication performance of Ti2CTx coatings with reduced friction and extended durability. \u003cem\u003eTribol Int\u003c/em\u003e, Bd. \u003cb\u003e194\u003c/b\u003e, S. 109535, Juni (2024). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.triboint.2024.109535\u003c/span\u003e\u003cspan address=\"10.1016/j.triboint.2024.109535\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHwang, D. H., Kim, D. E. \u0026amp; Lee, S. J. \u0026bdquo;Influence of wear particle interaction in the sliding interface on friction of metals. \u003cem\u003eWear\u003c/em\u003e 225\u0026ndash;229. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/S0043-1648(98)00371-8\u003c/span\u003e\u003cspan address=\"10.1016/S0043-1648(98)00371-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (1999). Nr. I.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMansour, H. et al. \u0026bdquo;Structural, optical, magnetic and electrical properties of hematite (α-Fe2O3) nanoparticles synthesized by two methods: polyol and precipitation, \u003cem\u003eAppl. Phys. A\u003c/em\u003e, Bd. 123, Nr. 12, S. 787, Nov. (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00339-017-1408-1\u003c/span\u003e\u003cspan address=\"10.1007/s00339-017-1408-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\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-7574829/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7574829/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe development of advanced solid lubricants is critical for enhancing energy efficiency and durability in mechanical systems. In this study, we investigate the tribological performance of hybrid solid lubricant coatings composed of two-dimensional titanium carbide (Ti₃C₂Tₓ)- and niobium carbide (Nb₂CTₓ)-based MXenes. Coatings were applied via spray deposition onto AISI 304 stainless steel substrates and tested under dry sliding conditions against Al₂O₃ counterbodies. While individual MXene coatings exhibited limited friction stability, the hybrid Ti₃C₂Tₓ/Nb₂CTₓ coating demonstrated a significantly reduced and stable coefficient of friction (COF\u0026thinsp;\u0026lt;\u0026thinsp;0.2) throughout the test duration.\u003c/p\u003e\u003cp\u003eComprehensive surface and structural analyses of the wear tracks including SEM-EDS, Raman spectroscopy, and TEM revealed the formation of a compact, stratified tribofilm. We propose as a phenomenological model that under tribological stress, the hybrid system undergoes adaptive reconfiguration: Ti₃C₂Tₓ anchors to the substrate, enhancing adhesion and mechanical integrity, while Nb₂CTₓ migrates to the sliding interface, acting as a sacrificial layer. This dynamic redistribution results in a synergistic interaction that enhances tribochemical resilience and wear resistance.\u003c/p\u003e\u003cp\u003eThese findings establish hybrid MXene coatings as a promising strategy for engineering next-generation solid lubricants, offering new pathways for the design of high-performance, energy-efficient coatings in demanding industrial applications.\u003c/p\u003e","manuscriptTitle":"Hybrid MXene Coatings: Unlocking Synergistic Lubrication Properties of Ti₃C₂Tₓ and Nb2CTx MXenes for Improved Tribological Performance","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-30 12:54:30","doi":"10.21203/rs.3.rs-7574829/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-09-30T13:31:24+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-29T15:39:31+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-26T03:26:29+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"111957638687752412640148699257742332805","date":"2025-09-21T05:40:35+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"93473439279324980327805172851751242290","date":"2025-09-21T02:14:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"313180514204600672635331017835431487877","date":"2025-09-19T08:27:01+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-19T01:22:26+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-09-18T16:47:23+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-17T11:41:48+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-09-12T11:29:38+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-09-09T14:16:20+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":"9057c763-2be2-4cdc-b0d8-af7298e17f5e","owner":[],"postedDate":"September 30th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":55580049,"name":"Physical sciences/Engineering"},{"id":55580050,"name":"Physical sciences/Materials science"}],"tags":[],"updatedAt":"2025-12-29T16:08:00+00:00","versionOfRecord":{"articleIdentity":"rs-7574829","link":"https://doi.org/10.1038/s41598-025-32533-6","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2025-12-22 15:58:07","publishedOnDateReadable":"December 22nd, 2025"},"versionCreatedAt":"2025-09-30 12:54:30","video":"","vorDoi":"10.1038/s41598-025-32533-6","vorDoiUrl":"https://doi.org/10.1038/s41598-025-32533-6","workflowStages":[]},"version":"v1","identity":"rs-7574829","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7574829","identity":"rs-7574829","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}