{"paper_id":"470ff82b-87d5-43e6-84df-a24656c9632b","body_text":"Facile synthesis of Samarium (Sm 3+ ) doped Cobalt-iron oxide nano ferrite as an advanced electrode material for supercapacitor applications | 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 Research Article Facile synthesis of Samarium (Sm 3+ ) doped Cobalt-iron oxide nano ferrite as an advanced electrode material for supercapacitor applications Syed Khasim, APSAR PASHA, Ramakrishna BN, Prathibha B.S, Koushalya P.R This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4177651/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Herein, we present the design and fabrication of samarium (Sm 3+ ) doped cobalt-iron oxide ferrites nanocomposites for utilization as an efficient energy storage material. We have employed a simple, low cost and quick one step solution combustion method used to synthesize CoFe 2 − x Sm x O 4 (x = 0.0, 0.050, 0.075 and 0.1) ferrites composites. The synthesized CoFe 2 − x Sm x O 4 NPs undergo different analytical and spectroscopic characterizations methods like scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and ultraviolet visible (UV-visible) analytical and spectroscopic methods that used to confirm the morphological and structural properties of the synthesized NPs. The electrochemical properties synthesized ferrites composites were significantly improved after inclusion of rare earth (RE) metal such as samaniuim (Sm 3+ ) nanoparticles (NPs) into the host cobalt-iron-oxide. It was notice that the creation of single phase in pure CoFe 2 − x Sm x O 4 ferrite remains unaltered by the mechanism of doping even in the ferrites composite. Nevertheless, doping of RE metal significantly influences over the morphological and structural properties, further more enhancement in the electrochemical performance of samarium doped CoFe 2 − x Sm x O 4 ferrite composite. The highest specific capacity about 850 F/g was achieved for CoFe 2 − x Sm x O 4 (x = 0.1) composite electrode material, which shows more superior in compare to pure CoFe 2 − x Sm x O 4 (x = 0) which is about 340 F/g. However, CoFe 2 − x Sm x O 4 (x = 0.1) composite shows a superior capacitance retention of the order of 98% even after 5000 cycles of operation at a scan rate of 250 mV/s. The electrode material fabricated by using CoFe 2 − x Sm x O 4 ferrite composites behave as positive electrode and at the same time activated nickel behave as negative electrode which is render an energy density of 30.16 Wh/kg at a power density of 400 Wh/kg. The results obtained in presented studies offer a hopeful way for the fabrication high-performance electrode material for supercapacitor which is more suitable for light weight electronic devices, electric vehicles, and forthcoming generation supercapacitor applications. Rare earth (RE) Samarium NPs Solution combustion method Ferrite nanocomposite Electrochemical analysis Electrode materials and Supercapacitor Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 1. Introduction The quickly enhancing prices of non-renewable fuels, environmental pollution, geothermal and global warming issues have become more severe problems and some of the major challenges were facing for the human progress. In these contests many research has been dedicated for the development of renewable and clean energy for energy storage devices [ 1 ]. To meet the increasing energy storage requirement in modern society, the number energy storage equipment’s available like supercapacitor, lithium-ion batteries, and lead acid batteries etc [ 2 – 3 ]. Amid of all supercapacitors (SCs) have been appeared as suitable candidates for forthcoming generation energy storage device due to their unique features like more power density, fast charging and discharging process, stability in long cycles, more reversible mechanism, and ecofriendly nature [ 4 – 5 ]. As per the energy storage system is concern, the energy storage electrode materials could be split into two types viz. electric double layer capacitor (EDLCs), which stored charges via formation of electric double layer and pseudo capacitor which can stored charges via Faradic process take place between the electrode and electrolytic solution [ 6 – 8 ]. In comparison with the EDLCs, generally pseudo capacitor exhibits superior specific capacitance and power density, nevertheless the lower conductivity and long-term cycle stability are greatly influences on their device performance in the real time practical applications [ 9 – 10 ]. Thus, many efforts have been paid to fabricate of the composites that can rendered improved charge density and stability in long cycles of operations. Presently, transition metal oxides (TMOs) nanocomposites have gained much interest for researchers across the globe to utilize as an active electrode material for supercapacitors and battery applications owing to their superior redox properties, large specific capacitance, ecologically friendly nature, and easy accessibility [ 11 – 13 ]. Amid the many TMOs, cobalt-iron oxide is deliberated a most suitable electrode materials for supercapacitor practical relevance’s due to their many oxidations state (Co 3+ /Co 2+ ), superior theoretical capacity, tuneable electrochemical properties, and good level of thermal stability [ 14 – 15 ]. Therefore, in majority of the cases reported in the earlier literature, the value of the specific capacity recorded for cobalt-iron oxide ferrite electrode is extremely lower in compare to theoretical calculated capacity value. At present, it is great challenge to fabricate a novel nano ferrites composite that is treated as preferable material for gain higher electrochemical performance [ 16 ]. The perovskite-based ferrite nanocomposites were very prominence in the studies on energy storage applications because of their originality in their structure as well properties. This kind of geometry has been greatly examined in different applications in gas sensors, solar cells, electronics, and in supercapacitors [ 17 ]. The chemical formula we used to represent the perovskite geometry is ABO 3 , here A and B shows the rare earth (RE) sites like lanthanum, samarium, caesium, neodymium, and yttrium etc and transition metals like iron, cobalt, nickel, and cobalt in order [ 18 – 19 ]. The plenty of vacancies in oxygen lattice in crystal structure play a vital role in the electric charge storage kinetics mechanism [ 20 ]. Recently, rare-earth metal oxide materials have been interested notable attention because of their exceptional features in variable electrochemical sites [ 21 – 22 ]. Recently, Shyamli Ashok C et al. synthesized Co x Ni 1−x O ferrites composites of variable concentration of cobalt and nickel NPs via solution combustion method. The synthesized ferrite NPs were characterized through different analytical and spectroscopic methods. In these studies, they found that doping of NPs into the ferrites, the electrochemical properties were significantly improved. The Co x Ni 1−x O composites at 0.5A/g exhibited highest specific capacity about 325 C/kg with superior level of capability, improved charging and discharging and stability in long cycles [ 23 ]. Bablu Mordina et al. fabricated NiFe 2 O 4 ferrites composite for possible energy storage applications. The ferrite composites were prepared via co-precipitation technique and performed XRD analysis for the single-phase confirmation in the synthesized ferrite composites. The specific capacity was found to be 400 C/g for highest NPs doping sample at current density of 2.5 A/g. The energy density and power density of 27.71 Wh/kg and 14.49 kW/kg are attained at 1 and 20 A/g current density values respectively. This research group drawn the conclusion that, by doping suitable rare earth NPs into the NiFe 2 O 4 ferrites, the electrochemical properties significantly improved could be utilized as an electrode material for the fabrication of supercapacitors [ 24 ]. Vidyadevi A. Jundale et al. prepared cobalt ferrite thin films electrode material by using chemical spray pyrolysis method for supercapacitor application. The prepared CoFe 2 O 4 thin films were characterized via SEM, UV-visible and XRD for morphological and confirmation cubical phases in the synthesized ferrites samples. The specific capacitance of the synthesized CoFe 2 O 4 thin film was recorded to be 369 F/g at a scan rate of 2 mVs − 1 . This group confirms that, the prepared electrode material is pseudocapacitive nature with quick charging and discharging rates. The higher NPs doping ferrite thin film shows that improved power density and energy density in the order of 27.14 Wh/kg and 28.74 kW/kg respectively at constant current density of 2 mA/g [ 25 ]. The above-mentioned previously published literatures motivated us to carry out the present studies in cobalt-iron-oxide ferrite system for possible utilization of electrode materials in supercapacitor. In the presented research work, we are interested to enhance the electrochemical performance of CoFe 2 − x Sm x O 4 ferrite by inclusion of samarium NPs. We employed very simple, low cost and one step solution combustion method to synthesis samarium (RE) doped cobalt-iron-oxide ferrites composites. The other methods such as hydrothermal, chemical vapor deposition, and electrodeposition that need improved instruments and operating condition, but the solution combustion technique could be manageable method to gain porous nature of ferrite NPs [ 26 ]. In the presented work, we have systematically demonstrated a simple method used to fabricate high performance samarium doped CoFe 2 − x Sm x O 4 ferrite composites electrode materials for supercapacitor applications prepared via solution combustion method. We have systematically studied the surface morphology, structural and electrochemical properties of samarium doped CoFe 2 − x Sm x O 4 ferrite and effects of samarium dopant concentration in the characteristics features of CoFe 2 − x O 4 composites was investigated in detail. We have seen that inclusion of samarium NPs in to the CoFe 2 − x O 4 ferrite, there is a significantly improved the electrochemical features of CoFe 2 − x Sm x O 4 ferrite composites and excellent electrochemical work function was shown by the CoFe 2 − x Sm x O 4 (x = 0.1) composite as they have given specific capacity of 850 F/g at constant 50 mV/s, this value almost three folds larger than the pure CoFe 2 − x Sm x O 4 (x = 0.0) ferrite sample. However, the prepared CoFe 2 − x Sm x O 4 (x = 0.1) composite sample exhibited 98% of capacitance retention even after the running of 5000 cycles of operations. By measuring the parameters like cyclic voltammetry, prolonged charging and discharging cycles and impedance spectroscopy results were employed to judge the performance of the electrode materials tested for the supercapacitors applications and all these parameters represented by using appropriate mathematical equations [ 27 ]. Hence, this current research work suggests a simple method to synthesized more porous samarium doped CoFe 2 − x O 4 ferrites in search of excellent electrode materials based on the hybrid transition metal oxides (TMOs) for new generation supercapacitors. Intend, this presented study will guide the researchers and device technocrats across the world, how the features of the electrode materials could be recognized and their superior electrochemical performance should be offered by prudent utilization of proper electrode materials for supercapacitor application. 2. Experimental 2.1. Materials and Methods: 2.2 Synthesis of samarium doped cobalt iron ferrites nanocomposite: The routine solution combustion method was utilized to prepare CoFe 2 − x Sm x O 4 (x = 0.0, 0.050, 0.075 and 0.1) ferrite NPs. The chemicals like cobalt nitrate hexahydrate [Co (NO3)2.6H2O], ferrous based nitrate nano hydrate [Fe (NO3)3.9H2O], samarium nitrate [Sm (NO3)3], urea [CO(NH2)2] and glucose [C6H12O6] are procured from Sigma Aldrich (India). During preparation, the metal nitrate powder salt act as an oxidizing agent while urea and glucose behave as reducing agents during the synthesis process. In 500 mL round bottom conical flask was taken stoichiometric ratio of two oxidising and reducing agent materials are mixed thoroughly and added deionized water into the beaker to achieve the superior quality of ferrite NPs. The achieve highly pure nanocomposite solution was uniformly mixed up to a time duration of 10 hours with the help of magnetic stirrer and rotation speed was maintained about 2000 rpm to achieve homogenously dispersed nano ferrite solution. The prepared nano ferrite solution was shifted into the muffle furnace and kept at a temperature of nearly 500 o C. The fine mixed nano ferrite solution was permitted to boil at high temperature to eliminate all types of poisonous gases and rest mass of nano ferrite was dried to achieve the final yield product [ 28 ]. The detailed flow chart of synthesis method of the novel CoFe 2 − x Sm x O 4 ferrite NPs was shown in the Figure. 1. The product of ferrite nano powder was attained in the type of black puffy colured and light foamy in mass. This nano ferrite powder was shifted into the agate mortar, and fine grinded to achieve fine ferrite nano powder. Therefore, the synthesized ferrite NPs powder was utilized to execute different analytical and spectroscopic characterization. To measure electrochemical parameters, we have prepared the ferrite composite electrode on nickel mesh towards the testing of supercapacitors applications. 2.3 Preparation of electrode material for supercapacitor testing: To fabricate CoFe 2 − x Sm x O 4 as working electrode, 80% CoFe 2 − x Sm x O 4 nano ferrite powder, 15% of pure graphene powder and 5% of PTFE solution which act as a binder was well grinded in an agate motor for a duration of 1 hour to achieve a homogeneous thin sheet. This prepared sheet was pasted over the nickel mesh. After the coated with the paste, these pasted electrodes were compressed at 20 MPa for the duration of 5 minutes to ensure the electrical contact between the nickel mesh and the active material. The back side of the electrode and the contact wire was tightly insulated by employing a Teflon tape to achieve an electrode with an active area for the measurements about 2 cm ×1 cm and prior use, it was immersed in the 6.0 M KOH solution for a duration of 60 minutes to achieve good level of electrode contact with the electrolyte. 2.4 Materials Characterization: The exterior morphology of the synthesized CoFe 2 − x Sm x O 4 (x = 0.0, 0.050, 0.075 and 0.1) ferrite nanoparticles (NPs) were performed by using scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) (Ultra Scan 60: Japan). The nano sized morphology in the prepared ferrite composite was recorded by using transmission electron microscope (TEM) (Thermofisher TEM TALOS with CMOS camera system). The creation of mono-phase crystal structure in the prepared nano ferrite composite samples were tested by employing powder X-ray diffraction method (XR Ultra Dynamics-400, UK) at the region 2Ɵ = 20 o to 80 o Cu Kα (λ = 1.5418 Å). The existence of different chemical groups and variable stretching frequencies present in the synthesized nano ferrites composite were inspected via Fourier Transform Infrared Spectroscopy (FTIR) (Thermo Nicolet, Avatar 370 -India). The optical absorption features of prepared ferrite composites were achieved by employing UV–visible spectrometry (Perkin Elmer-Canada) in the range of 300 nm–600 nm. The cyclic voltametric analysis was executed on a CHI604E potentiostat electrochemical analyser with a three-electrode assembly, which comprises of CoFe 2 − x Sm x O 4 electrode, platinum wire, and Ag/AgCl as accordingly working, counter, and reference electrodes correspondingly and the electrolyte solution was taken as 6.0 M KOH solution. The applied potential range was 0.2 V to 0.6 V (towards Ag/ AgCl electrode) and the standard scanning rate was set in the order of 5 mV/s, 10 mV/s, 15 mV/s, 20 mV/s and 25 mV/s, for the Galvanostat charge-discharge measurement at a current density of 5 Ag − 1 inside the potential window of 0.0V- 0.6V versus Ag/AgCl. In addition to above said parameters, the AC amplitude of 5 mV and frequency rangime of 1 Hz to 1 MHz we applied for electrochemical impedance spectroscopy (EIS) tests were also recorded. 3. Results and discussion 3.1 Scanning electron microscope and EDS analysis: The scanning electron microscopy technique used to characterize the surface morphologies of samarium doped cobalt-iron ferrite composites. Figure. 2 (a-d) shows the SEM micrographs of CoFe 2 − x Sm x O 4 (x = 0.0, 0.050, 0.075 and 0.1) ferrite NPs. The SEM images displays a flake type morphology with more porous structure [ 29 – 30 ]. These large pores are generated because of liberation of more gases at the time combustion process. The undoped ferrite sample (x = 0.0) shows smooth and homogenous without formation of much pores in its morphology. By inclusion of rare earth (RE) like samarium NPs into the cobalt-iron ferrites, morphology of composites was drastically improved, which is witnessed for the superior advanced applications in energy storage devices. It could be observed that, amid the prepared ferrite samples, CoFe 2 − x Sm x O 4 (x = 0.1) shows more porous morphology behaviour with large open pores, which is facilitate more and more active areas. However, when the doping percentage of samarium was enhanced to x = 0.1 into the CoFe 2 − x Sm x O 4 , the particle tends to be highly agglomerate which is reflects from the SEM micrograph. The optimized concentration of x = 0.1 of samarium NPs doped in cobalt-iron ferrite shows highly efficient electrochemical performance. “The energy dispersive X-ray spectroscopy (EDS) analysis” was carried out to prove the variable elemental composition exists in the prepared CoFe 2 − x Sm x O 4 ferrite composite. Figure. 3 (a and b) shows the EDS spectra of x = 0.0 and x = 0.1 ferrite composite. The EDS tests of the synthesized ferrites sample was done in the range of 0.2 keV to 14 keV. From the Figure.3 (a) for x = 0.0 ferrite sample, the prime element such as cobalt, iron and oxygen were existed. At the same time in Figure.3 (b) ferrite sample, the prime elements such as samarium, cobalt, iron, and oxygen were present. By using EDS method, determination of elemental composition is well obeyed with the theoretically determined stoichiometry values, both the values were elucidated in the Table.1. 3.2 Transmission electron microscope (TEM) analysis: The “transmission electron microscopy (TEM) analysis” was done for the synthesized ferrite samples to prove the nanostructure features in the samples. Figure.4(a) shows the low magnification TEM image of CoFe 2 − x Sm x O 4 (x = 0.1) composite. The NPs are approximately flake type morphology with more porous structure [ 31 ]. These large pores are generated because of liberation of more gases at the time combustion process. The mean average particle dimension of 38 ± 4 nm which is good agreed with the average particle size (40 ± 5nm) calculated by using Sherrer equation. The SAED distribution structure of CoFe 2 − x Sm x O 4 (x = 0.1) composite was illustrated in the Figure.4(b). It comprises of many concentric circular rings with bright spots of crystallites shows the polycrystalline features of spinel crystal geometry ferrites NPs with high degree of crystallinity. The maximum bright ring generated because of the diffraction from the crystal plane (311). The rings inside the bright circular rings could be described for diffraction occur from the crystal plane (220) and at the same time exterior circular rings could be nominated to the diffraction effects from the crystalline planes (400), (422), (511) and (440) respectively. The results obtained from TEM and SAED pattern clearly validate that Sm 3+ NPs were homogenously distributed in the Co-Fe-O 4 ferrites structure without any formation of secondary phases [ 32 ]. 3.3 X-ray diffraction analysis (XRD): The powder XRD pattern of the prepared CoFe 2 − x Sm x O 4 (x = 0.0, 0.050, 0.075 and 0.1) NPs recorded at ambient temperature were elucidated in the Figure.5. The recorded XRD spectra shows prominent peaks very close to the planes (100) (101) (200) (210) (211) (300) (311) (401) and (411) shows mono phase features of cubic spinel ferrite composite with well match with the standard JCPDS: Card number: 21–1076). Almost all-important peaks were existed in higher NPs concentration doping Co-Fe-O 4 ferrite composite. The XRD spectra shows the formation of Fd3m ionic space and well formation of single phase in the spinel cubical shape. The more ionic radius of Sm 3+ (1.05 A˚) which is well associated with the radius of Fe 3+ (0.64 A˚), these major changes might be believed that the inclusion of positive charge substituted by iron in cobalt-based ferrite nanocomposite. The inclusion of RE like samarium NPs into Co-Fe-O4 ferrite, there is no such major modification was observed in the crystal structure. To estimate the crystal size, we employed Scherrer’s equation [ 33 ] which is well agreement with grain size determined via SEM analysis. $$D=\\frac{k\\lambda }{\\beta cos\\theta }$$ In the above equation, D indicates the crystallite size, k be the dimensional geometry factor which is nearly 0.9 for round shaped particles, λ be the wavelength of X-ray utilized, β is the FWHM intensity, and θ be the diffraction angle. The determined crystallite size through XRD analysis is nearly in order of 40 nm. It is very curious to observe that the value of lattice parameter and lattice volume was slight changes in doped NPs ferrite composite. The drop in the lattice value due to variation in the ionic radius that proved the dopant blend on substituted lattice site. From the XRD spectra it was clearly demonstrated that, there is marginal change in crystal lattice parameter of the CoFe 2-x Sm x O 4 ferrite composite owing to cationic modification in entire crystal structure. In particular, the crystallite size exhibits the same behaviour and reduction considerably when the inclusion of samarium NPs into the cobalt-iron ferrites. 3.4 Fourier transform infrared spectroscopy (FTIR): The consequences of doping by using samarium (RE) in cobalt-iron oxide ferrite composite over the structure and its surface morphology was measured through spectroscopic method. The trend of FTIR spectra of CoFe 2 − x Sm x O 4 (x = 0.0, 0.050, 0.075 and 0.1) ferrite NPs is shown in the Figure.6. The major peaks around 606 and 660 cm − 1 stretching vibrations may be due to the vibration of Fe-O and Co-O bonds near to octahedral and tetrahedral areas of ferrite composite. The strong lattice vibrations near at the stretching frequencies of 440 and 808cm − 1 are owing to symmetric lattice vibration of the samarium and cobalt metal NPs in their localized areas [ 34 ]. The major lattice vibration of peak around the stretching frequency 3500 cm − 1 might be due to O-H lattice vibration arises due to the absorbed water molecules in the ferrite composite. The lattice vibration of stretching frequencies nearly 1120, 1153 and 1380 cm − 1 are the characteristic vibration of cobalt-iron oxide ferrites. Hence, the formation of cations with different ionic radius leads to the creation of real crystals. In particular, the oxygen atoms are liberated from their normal sites to create the empty site for the cations with the larger ionic radius [ 35 ]. This examination was good agreements with the XRD analysis for the creation of single phases before and after the inclusion of samarium NPs into the CoFe 2 − x Sm x O 4 composite. 3.5 UV-Visible spectroscopic analysis: UV-visible spectroscopy technique largely utilized technique for optical characterization in majority of the ferrite based composite materials. The UV-visible spectra of CoFe 2 − x Sm x O 4 (x = 0.0, 0.050, 0.075 and 0.1) NPs were recorded in wavelength range of 200nm to 800nm are illustrated in the Figure.7. By enhancing the concentration of samarium NPs into the CoFe 2 − x Sm x O 4 , the intensity of the peak marginally increases. The major absorption peaks show the truth that photons are largely absorbed approximately 600 nm, this wavelength region comes under the range of visible area of the EM spectrum. The prime reason in the change of UV–visible spectra of the ferrite composite is owing to its surface morphology and grain size present at the larger concentration of samarium treated cobalt-iron oxide ferrite sample. It was noticed from the UV–visible spectra, the more energy transition can be owing to the π-π* ferrite composite [ 36 ]. In the UV–visible spectra the band commencing from the 700 nm have been assigned as free carrier tail. We can easily interfere from UV-visible spectra, the intensity of the peak gradually increasing the percentage of samarium NPs into the cobalt-iron-oxide ferrite. We observed form UV-visible absorption spectra, by enhancing the concentration of NPs into the cobalt-iron-oxide ferrite, the peaks intensity gradually improved. This improved intensity of the peak shows that the good level of interaction between samarium (RE) and iron-nickel oxide ferrite. 4. Electrochemical characterizations 4.1 . Cyclic voltammetry (CV) studies : To study the charge storage applications of the synthesized CoFe 2 − x Sm x O 4 nanocomposite ferrites, cyclic voltammetry (CV) measurement was done by using three electrode assembly employing 6 M KOH as the electrolyte solution. Figure.8 shows the variation of cyclic voltammetry CoFe 2 − x Sm x O 4 (x = 0.0, 0.050, 0.075 and 0.1) nanocomposite ferrites with operating window of − 0.2 to 0.8 V. The CV curves of all the synthesized ferrite samples shows a couple of major redox peaks which exhibit the faradaic features of the material. This is relatively variable from the CV curve shows by electrical two-layer capacitance features, which is generally very near to perfect rectangular geometry [ 37 – 38 ]. It is observed from CV curve, the electrode material shows unique features like the anodic peak rises to more potential and at the same time the cathodic peak moved to lower potential value which reflects the fact that good level of electrochemical reversibility [ 39 ]. Fascinatingly, at lower value scan rates the pores distribution over the cathode are well present for the electrolyte particles and therefore improving the capacitance behaviour of the ferrite composite. In distinction, the pores over the electrode could be easily available for the electrolyte ions, which effects leads to the improved capacitance behaviour at lesser scan rates. Additionally, as we enhance the potential scan rate, there is a small shift of the oxidation peak in the direction of higher positive potential and the reduction peak near to negative direction. These effects might be due to the uncompensated resistance and polarization mechanism in the region of more scan rate [ 40 ]. The variation of CV curves for CoFe 2 − x Sm x O 4 (x = 0.1) ferrite composite at variable scan rate were illustrated in the Figure.8 (b). The CV curves shows that approximately quasi rectangular geometry for variable scan rates like (5 mV/s to 250 mV/s) shows a perfect capacitive feature of the ferrite composite owing to more reversible redox chemical reactions of CoFe 2 − x Sm x O 4 and the exterior surface electro adsorption of samarium NPs. The value of the specific capacitance (C sp ) for the prepared CoFe 2 − x Sm x O 4 (x = 0.0, 0.050, 0.075 and 0.1) ferrite composites were calculated by using the equation based on the CV as follows. $${C}_{sp}=\\frac{S}{m\\times \\delta V\\times K}$$ In the above equation S indicates area under the CV curves, m be the weight of ferrite deposited over the electrode material, δV be the voltage window and K be the variable scan rate. One of the important parameters used to characterized the active surface area available in the electrode material is voltametric charge distribution (q*) to judge the superior performance for supercapacitor applications [ 41 ]. Generally, the charges present in both interior and exterior surfaces will donates to the bulk charges stored in an active electrode material. Hence, the total charges stored in an electrode material can be represented by using the equation. The value of the volumetric charges (q*) could be determined by applying integration to the CV curves at variable scan rates and dividing with the geometrical area of the electrode material. From the Figure.9 (a) and (b) it is very clearly observed that both the values of q* and 1/q* were linearly varies with the V − 1/2 and V 1/2 in order with respect different weight percentage of samarium NPs into the Co-Fe-O 4 ferrite sample. This trend might be owing to the irreversible redox mechanism and ohmic drops leads to the more resistance of samarium doped Co-Fe-O 4 ferrite composites. The extrapolation of charge q* with respect to V − 1/2 =0 (Figure. 9a), which signifies q* out resemble easily available to outer charges at the same time the extrapolation of 1/q* as shown in (Figure. 2b) which gives the q* total . The linear trends of both q* and 1/q* were greatly suggests that the enhancement in the more charge gathering in the ferrite nanocomposite [ 42 ]. The more charge accumulation in the ferrite composite samples exhibit a major dependence over the doping of samarium (RE) NPs into the Co-Fe-O 4 nanocomposite ferrite. The enhancement in the charge accumulation in the ferrite nanocomposites were ascends primarily due to the enhancement in the active surface area as well as pores size spreading owing to the inclusion of samarium NPs into the host Co-Fe-O 4 nanocomposite ferrite as clear from SEM micrographs. Further, to interpret the synergetic effects of samarium doping into the Co-Fe-O 4 ferrite composite over the active surface area and pore size, we have done the BET analysis of all synthesized ferrite composites sample and obtained data is given in the Table.2. The data obtained from BET analysis we conform that by the doping of samarium NPs into the Co-Fe-O4 ferrite composites, there is significant improvements in the surface area, pore size and volume of the pore in compare to the undoped ferrite sample, these modification in the ferrite nanocomposites play very crucial role in the improvements in the electrochemical performance of the ferrites-based nanocomposites. 4.2 Electrochemical impedance spectroscopy (EIS) studies: The capacitive features of pure CoFe 2 − x O 4 and CoFe 2 − x Sm x O 4 (x = 0.0, 0.050, 0.075 and 0.1) ferrite composites are examined via “electrochemical impedance spectroscopy” (EIS) by recording charge transfer resistance (R ct ) and equivalent resistance in the series combination (R eq ). Figure.10 shows the Nyquist plots of CoFe 2 − x Sm x O 4 (x = 0.0, 0.050, 0.075 and 0.1) ferrite composites are recorded at 1Hz to 1MHz frequency region exhibit nearly linear behaviour at the lower frequency’s region, this kind of behaviour indicates that the prepared electrode material by exactly capacitive nature [ 43 ].The EIS features of the ferrite composites from the Nyquist plots over the total applied frequencies region also exhibit fascinating features of this kind of material as a higher performance electrode because of lower R ct values of CoFe 2 − x Sm x O 4 (x = 0.1) ferrite composite. From the Nyquist plots one can easily interfered that the geometrical resistance value of the synthesized ferrite composite reduces considerable at the same time the capacitance behaviour enhanced with inclusion of samarium NPs into the Co-Fe-O 4 ferrites. The inclusion of Sm 3+ NPs inside the Co-Fe-O 4 ferrites is believed to enhances the active surface area as well as pore size distribution that led to the deduction in the interior resistance of the ferrite composites. The lower R ct value of CoFe 2 − x Sm x O 4 (x = 0.1) is because of the exitance of many conductive pathways and larger diffusivity of the electrolyte ions present in the tested sample [ 44 ]. From the Nyquist plots we can conclude that the higher concentration samarium NPs doping into Co-Fe-O 4 ferrite with enhanced electrical conductivity and almost linear variation of impedance at very lower frequencies regime, hence conclude the super capacitive features of the synthesized of electrode material for supercapacitor applications. 4.3 Galvanostatic charge discharge (GCD): To examine the electrochemical features of the as synthesized CoFe 2 − x Sm x O 4 (x = 0.0, 0.050, 0.075 and 0.1) ferrite composites samples, we have carried out the charging and discharging tests were done in 6 M KOH high concentrated electrolyte solution. The measurements were done at the potential range of 0 to 0.6 V at constant current density of 50 A/g is illustrated in the Figure.11 (a). It is very clearly visible from the plots that there are two well visible areas in the plots. The region starting from 0 to 0.55 V exhibits the two-layer capacitive features here there is an almost linear trend of potential with respect to time. The Redox process of the synthesized ferrite samples was shown by the sloped trend of applied potential with a function of time in the region of 0.36 to 0.54 V. During the cycling process, there is existence of Faradaic reactions was evident that voltage plateau at this operated voltage. Generally, the plateau potential value of charging mechanism is much higher than that of discharging mechanism. These effects might be due to the change in kinetics values of the redox chemical reaction at the time of charging and discharging mechanism which turn into electrode polarization [ 45 ]. We can draw the conclusion from GCD profiles, the charge storage in CoFe 2 − x Sm x O 4 composites is primarily because of the Faradaic mechanism, which is well correlated with the CV tests. Amid of the prepared ferrite sample CoFe 2 − x Sm x O 4 (x = 0.1) composite sample exhibits more discharging time in compare to other prepared ferrites samples, which reflects the facts that larger specific capacity. Figure.11 (b and c) shows the Galvanostatic charge–discharge (GCD) cycles for CoFe 2 − x Sm x O 4 (x = 0.1) composite for first cycle and 2000 cycles respectively. The geometry of the GCD curves is associated to the pseudocapacitive behaviour of the prepared electrodes materials [ 46 ]. The specific capacitance values during charging and discharging process could be determined by employing the equation [ 46 ]. $${C}_{sp}=\\frac{i dt}{m ({v}_{f}-{v}_{i})}$$ In the above equation “i” be the subjected current, dt be the discharged time, m be the mass of ferrite composite coated on to the electrode and (V f −V i ) be the working potential window values. By inclusion of rare earth metal like samarium into the Co-Fe-O 4 ferrite the potential values are significantly improved, and noticeable coulombic efficiency was noticed from GCD plots for CoFe 2 − x Sm x O 4 (x = 0.1) nanocomposite with retention about 98% even after the 2000 cycles of operation. This result indicates that improved efficiency of the higher concentration samarium NPs doped Co-Fe-O 4 ferrite composites. The variation of specific capacitance with a function of current densities were shown in the Figure.12 (a). Both the parameters like discharge time and specific capacity reduces sharply with increase of current densities. This kind of trend might be due to non-availability of time for the electrolytes ions to migrates totally inside the electrode at the region of Faradaic chemical reactions take place. As these consequences some area of the electrode surface unavailable to the electrolyte’s ions at the region of higher current [ 47 ]. Among the prepared ferrite samples CoFe 2 − x Sm x O 4 (x = 0.1) composites exhibit 98% specific capacity retention value demonstrates good electrode material for supercapacitor applications. Furthermore, we have carried out the cycling stability tests for CoFe 2 − x Sm x O 4 (x = 0.1) composites electrode material by revising the CV rotations over the scan rate of 250 mV/s in 6 M KOH electrolytic solution for a duration of 5000 times. The variation of capacitance retention percentage with a function of subjected cycle numbers for CoFe 2 − x Sm x O 4 (x = 0.1) composite was illustrated in the Figure.12 (b). It is very clear from the plots the 98% of the specific capacity was remain stable even after the end of 5000 cycles of operations. Initially, it was found that there was a marginal reduction in the specific capacity up to the 2000 cycles of operation and there after it turn to nearly stable and moved to 98% at the end of 5000 cycles of operations [ 48 ]. In our presented research results we confirmed that CoFe 2 − x Sm x O 4 (x = 0.1) composite electrode material exhibits fabulous cycling performance for long cycles of operations. The trend of energy density with a function of power density of CoFe 2 − x Sm x O 4 (x = 0.0, 0.050, 0.075 and 0.1) ferrite composites studied at room temperature which results in the Ragone plots is shown in the Figure.13. The energy density and power density of the synthesized ferrites are determined by using the equations. The lowest energy density for pure CoFe 2 − x Sm x O 4 (x = 0.0) ferrite sample was recorded nearly equal to 14 Wh/kg at a power density of 300 Wh/kg, however CoFe 2 − x Sm x O 4 (x = 0.1) ferrite composite exhibit outstanding enhancement in the power density about 30.16 Wh/kg at an applied power density of 400 Wh/kg. The higher concentration NPs ferrite composite shows improved energy density values with respect to the power density, which reflects the facts that the superior capacitive behaviour of the ferrite composites [ 49 – 50 ]. The enhanced specific capacitance, specific capacitance retention, the energy and power density of the CoFe 2 − x Sm x O 4 (x = 0.1) ferrite composite exhibit fabulous performance in compare to recent literature published on cobalt-iron-oxide ferrites [ 51 ]. Therefore, by doping method utilised in this current research work plays very prominent role in the enhancement of supercapacitor properties. 5. Conclusion In conclusion, we utilized a simple, less expensive, very fast, one step method of solution combustion technique used to synthesize samarium doped cobalt-iron oxide ferrites composites. The Sm 3+ and Fe 3+ NPs were effectively doped at variable concentrations into the cobalt oxide ferrite system, without altering the phase of pure cobalt oxide ferrite. The presence of any kind of secondary peaks before and after doping of NPs as well as creation of single phase in spinel ferrites was validated via X-ray diffraction technique. The advanced characterization tools like SEM, EDX, TEM, FTIR and UV-visible analytical and spectroscopic techniques were used to validates the surface morphology and the existence of only constituent elements and variable functional groups exists in the synthesized ferrites composites. BET analysis exhibit that the percentage of Sm 3+ NPs doping into the host ferrites over the pore size and surface area. Owing to the improved electrical conductivity due to fast charge carriers’ migration after the doping of rare earths NPs like Sm 3+ doped Co-Fe-O 4 ferrites composites shows superior electrochemical properties. The maximal specific capacitance of 850 F/g was shown by the CoFe 2 − x Sm x O 4 (x = 0.1) ferrite composite, which is far away excellent to pure CoFe 2 − x Sm x O 4 ferrite which is about 340 F/g. The synthesized ferrite composite shows that 98% of specific capacity retention even after the running of 5000 cycles of operation at 250 mV/s scan rate, which shows that good level of cycling performance. The electrode material fabricated by using CoFe 2 − x Sm x O 4 ferrite composites behave as positive electrode and at the same time activated nickel behave as negative electrode which render an energy density of 30.16 Wh/kg at a power density of 400 Wh/kg. The inclusion of rare earth (Sm 3+ ) NPs into the Co-Fe-O 4 ferrite nanocomposites proposed that its major usages in the field of energy storage applications especially supercapacitors. Declarations Data Availability: Data will be made available on request. CRediT authorship contribution statement: Syed Khasim: Methodology, Validation, Investigation and Writing the original draft of the manuscript. Apsar Pasha : Supervision, Conceptualization, Writing-review and editing the manuscript. B.N. Ramakrishna : Editing the manuscript, English language usage, analysis of materials characterization and sensor results. Prathibha.BS and Koushalya.PR : Acquiring the characterization data and Software analysis. Declaration of competing interest: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. References L.Liu, H.Zhao, Y.Lei, Review on nano architecture current collectors for pseudo capacitors, Small Methods 1800341 (2018) 1–25, https://doi.org/10.1002/ smtd.201800341. R.R. Palem, S. Ramesh, I. Rabani, G. Shimoga, C. Bathula, H.S. Kim, Y.S. Seo, H. S. Kim, S.H. Lee, Micro structurally assembled transition metal oxides with cellulose nanocrystals for high-performance supercapacitors, J. Energy Storage 50 (2022), 104712, https://doi.org/10.1016/j.est.2022.104712. 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Moholkar, Synthesis of NiO nanoparticles for supercapacitor application as an efficient electrode material, Vacuum 181 (2020), 109646, https://doi.org/ 10.1016/j.vacuum.2020.109646. Tables Table.1 EDS analysis of CoFe 2-x Sm x O 4 ferrites composites (x=0.0, x=0.050, x=0.075 and x=0.1). Fe 3+ and Samarium Concentration (x) Elements Composition Theoretical values Composition from EDS analysis X=0.00 Co 1 1.0136 Fe 2 1.9448 Sm 0 0.0000 X=0.050 Co 1 1.0243 Fe 1.95 1.8341 Sm 0.050 0.0501 X=0.075 Co 1 1.0232 Fe 1.925 1.8627 Sm 0.075 0.0713 X=0.1 Co 1 1.0232 Fe 1.90 1.8736 Sm 0.1 0.1028 Table.2 Surface area, average pore diameter and pore volume for different electrode materials. Sl.No Electrode material Surface area (m 2 /g) Average pore diameter (nm) Pore volume (cm 3 /g) 1 X=0 080.323 08.56 0.28 2 X=0.050 123.712 16.67 0.34 3 X=0.075 181.344 31.89 0.65 4 X=0.1 208.267 40.03 0.96 Additional Declarations Competing interest reported. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Cite Share Download PDF Status: Posted Version 1 posted 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. 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(Autonomous)\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Ramakrishna\",\"middleName\":\"\",\"lastName\":\"BN\",\"suffix\":\"\"},{\"id\":285080575,\"identity\":\"462082fb-48d2-4b54-8515-58f40a1490d3\",\"order_by\":3,\"name\":\"Prathibha B.S\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Government Srikrishnarajendra Silver Jubilee Technological Institute\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Prathibha\",\"middleName\":\"\",\"lastName\":\"B.S\",\"suffix\":\"\"},{\"id\":285080576,\"identity\":\"f4181a7f-e825-4303-9ef0-d4830793ce0c\",\"order_by\":4,\"name\":\"Koushalya P.R\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Government Srikrishnarajendra Silver Jubilee Technological Institute\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Koushalya\",\"middleName\":\"\",\"lastName\":\"P.R\",\"suffix\":\"\"}],\"badges\":[],\"createdAt\":\"2024-03-27 17:16:18\",\"currentVersionCode\":1,\"declarations\":\"\",\"doi\":\"10.21203/rs.3.rs-4177651/v1\",\"doiUrl\":\"https://doi.org/10.21203/rs.3.rs-4177651/v1\",\"draftVersion\":[],\"editorialEvents\":[],\"editorialNote\":\"\",\"failedWorkflow\":false,\"files\":[{\"id\":53960774,\"identity\":\"21fe0a0f-67cc-4727-95f5-94cc39f5087b\",\"added_by\":\"auto\",\"created_at\":\"2024-04-02 17:59:52\",\"extension\":\"png\",\"order_by\":1,\"title\":\"Figure 1\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":27382,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eFlowchart of preparation of ferrite powder CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x=0.0, 0.050, 0.075, 0.1).\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Figure.1.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4177651/v1/caf744b4e468ea906db49883.png\"},{\"id\":53959572,\"identity\":\"e3b7474a-d94b-4b49-af35-7a8662692f82\",\"added_by\":\"auto\",\"created_at\":\"2024-04-02 17:51:52\",\"extension\":\"png\",\"order_by\":2,\"title\":\"Figure 2\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":372542,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eSEM micrographs of CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (a) x=0.0 (b) x=0.050 (c) x=0.075 (d) x= 0.1 ferrite composite.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Figure.2.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4177651/v1/d7c7dbfec557fa04b8f79b74.png\"},{\"id\":53959574,\"identity\":\"e8d3fd56-795d-4f83-89e5-43b93555b0b8\",\"added_by\":\"auto\",\"created_at\":\"2024-04-02 17:51:52\",\"extension\":\"png\",\"order_by\":3,\"title\":\"Figure 3\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":137534,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eEDS spectra of CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (a) x=0.0 (b) x=0.1 ferrite composite.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Figure.3.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4177651/v1/79b78d7bd2245ef4adbf01ad.png\"},{\"id\":53959576,\"identity\":\"4f41fc32-a778-4349-8a1c-f4ebc58258c9\",\"added_by\":\"auto\",\"created_at\":\"2024-04-02 17:51:52\",\"extension\":\"png\",\"order_by\":4,\"title\":\"Figure 4\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":191285,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eTEM micrographs of CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (a) x=0.1 ferrite composite and (b) SAED distribution structure of CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x=0.1) composite.\\u0026nbsp;\\u0026nbsp;\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Figure.4.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4177651/v1/dcfcf6339581cedfb6608d11.png\"},{\"id\":53959575,\"identity\":\"43e52860-a085-4742-9953-77051470bb49\",\"added_by\":\"auto\",\"created_at\":\"2024-04-02 17:51:52\",\"extension\":\"png\",\"order_by\":5,\"title\":\"Figure 5\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":446192,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eXRD pattern of CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (a) x=0.0 (b) x=0.050 (c) x=0.075 (d) x=0.1 ferrite composite.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Figure.5.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4177651/v1/b7d8f451f9055024c0a60d15.png\"},{\"id\":53959577,\"identity\":\"d6276738-129a-4625-85f0-5016c71c28c6\",\"added_by\":\"auto\",\"created_at\":\"2024-04-02 17:51:52\",\"extension\":\"png\",\"order_by\":6,\"title\":\"Figure 6\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":312020,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eFTIR spectra of CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (a) x=0.0, (b) x=0.050 (c) x=0.075 (d) x=0.1 ferrite composite.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Figure.6.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4177651/v1/1eacf76ac2e2565ea80412c2.png\"},{\"id\":53959579,\"identity\":\"45847ba9-5fea-4e7a-af29-db0ef3d4b902\",\"added_by\":\"auto\",\"created_at\":\"2024-04-02 17:51:52\",\"extension\":\"png\",\"order_by\":7,\"title\":\"Figure 7\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":232338,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eUV-visible spectra of CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (a) x=0.0 (b) x=0.050 (c) x=0.075 (d) x= 0.1 ferrite composite.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Figure.7.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4177651/v1/8acc2e85c7b29731b82febc6.png\"},{\"id\":53960775,\"identity\":\"8ae2e18d-2436-4264-81e7-bc5566a99f23\",\"added_by\":\"auto\",\"created_at\":\"2024-04-02 17:59:52\",\"extension\":\"png\",\"order_by\":8,\"title\":\"Figure 8\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":351405,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eCyclic voltammograms of CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (a) x=0.0 (b) x=0.050 (c) x=0.075 (d) x=0.1 ferrite composite.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Figure.8.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4177651/v1/6c44b6c4b31cde67f4bf3ab1.png\"},{\"id\":53959582,\"identity\":\"cd21270e-5965-4f0f-9042-62ddaca1883e\",\"added_by\":\"auto\",\"created_at\":\"2024-04-02 17:51:52\",\"extension\":\"png\",\"order_by\":9,\"title\":\"Figure 9\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":174192,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eDependence of (a) voltammetric charge (q*) with inverse square root of scan rate (V\\u003csup\\u003e-1/2\\u003c/sup\\u003e) and (b) dependence of inverse voltammetric charge (1/q*) with square root scan rate (V \\u003csup\\u003e1/2\\u003c/sup\\u003e) of CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e x=0.0, x=0.050, x= 0.075 and x= 0.1 ferrite composite.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Figure.9.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4177651/v1/81bbcb5cc3b34c5ac6971708.png\"},{\"id\":53959584,\"identity\":\"544eb9b8-a34a-4443-9734-e6df5cc5e542\",\"added_by\":\"auto\",\"created_at\":\"2024-04-02 17:51:52\",\"extension\":\"png\",\"order_by\":10,\"title\":\"Figure 10\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":293493,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eNyquist plots for CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (a) x=0.0 (b) x=0.050, (c) x=0.075 (d) x=0.1 ferrite composite.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Figure.10.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4177651/v1/d0dc325028686c5c0ce15805.png\"},{\"id\":53960776,\"identity\":\"c473fa65-79b1-4680-8c9a-65cd63f40d4a\",\"added_by\":\"auto\",\"created_at\":\"2024-04-02 17:59:52\",\"extension\":\"png\",\"order_by\":11,\"title\":\"Figure 11\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":247363,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003e(a) Galvanostatic Charge-Discharge curve of CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x=0.0, x=0.050, x=0.075 and x=0.1 ferrite composite. (b). Galvanostatic Charge-Discharge curve of CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e for x=0.1 composite (1\\u003csup\\u003est\\u003c/sup\\u003e Cycle) (c). Galvanostatic Charge-Discharge curve of CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e for x=0.1 composite (2000th Cycle).\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Figure.11.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4177651/v1/84eaa1b4672a51f360de0c29.png\"},{\"id\":53960777,\"identity\":\"8b929c2b-24db-47e4-9388-b92eedc1b6f6\",\"added_by\":\"auto\",\"created_at\":\"2024-04-02 17:59:52\",\"extension\":\"png\",\"order_by\":12,\"title\":\"Figure 12\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":180076,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003e(a) Variation of specific capacitance vs current density for CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x=0.0, x=0.050, x=0.075 and x=0.1 ferrite composite: (b). Capacitance retention percentage vs cycle number for x=0.1 composite.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Figure.12.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4177651/v1/2a30e7bf01c4cd308df85de8.png\"},{\"id\":53959580,\"identity\":\"dd7cd4dd-2d0b-4e24-a171-de8e1284b22c\",\"added_by\":\"auto\",\"created_at\":\"2024-04-02 17:51:52\",\"extension\":\"png\",\"order_by\":13,\"title\":\"Figure 13\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":287463,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eEnergy density versus power density (Ragone plot) for CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (a) x=0.0 (b) x=0.050, (c) x= 0.075 (d) x= 0.1 ferrite composite.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Figure.13.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4177651/v1/d1524f9cbafccc8f5598c216.png\"},{\"id\":54377342,\"identity\":\"67367f62-7f89-465c-a52d-be7ff80b8001\",\"added_by\":\"auto\",\"created_at\":\"2024-04-09 14:31:53\",\"extension\":\"pdf\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"manuscript-pdf\",\"size\":2560702,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"manuscript.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-4177651/v1/09d4d0b7-6f1f-43cd-99bd-9b4602979c05.pdf\"}],\"financialInterests\":\"Competing interest reported. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\",\"formattedTitle\":\"Facile synthesis of Samarium (Sm 3+ ) doped Cobalt-iron oxide nano ferrite as an advanced electrode material for supercapacitor applications\",\"fulltext\":[{\"header\":\"1. Introduction\",\"content\":\"\\u003cp\\u003eThe quickly enhancing prices of non-renewable fuels, environmental pollution, geothermal and global warming issues have become more severe problems and some of the major challenges were facing for the human progress. In these contests many research has been dedicated for the development of renewable and clean energy for energy storage devices [\\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e1\\u003c/span\\u003e]. To meet the increasing energy storage requirement in modern society, the number energy storage equipment\\u0026rsquo;s available like supercapacitor, lithium-ion batteries, and lead acid batteries etc [\\u003cspan citationid=\\\"CR2\\\" class=\\\"CitationRef\\\"\\u003e2\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e3\\u003c/span\\u003e]. Amid of all supercapacitors (SCs) have been appeared as suitable candidates for forthcoming generation energy storage device due to their unique features like more power density, fast charging and discharging process, stability in long cycles, more reversible mechanism, and ecofriendly nature [\\u003cspan citationid=\\\"CR4\\\" class=\\\"CitationRef\\\"\\u003e4\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e5\\u003c/span\\u003e]. As per the energy storage system is concern, the energy storage electrode materials could be split into two types viz. electric double layer capacitor (EDLCs), which stored charges via formation of electric double layer and pseudo capacitor which can stored charges via Faradic process take place between the electrode and electrolytic solution [\\u003cspan additionalcitationids=\\\"CR7\\\" citationid=\\\"CR6\\\" class=\\\"CitationRef\\\"\\u003e6\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR8\\\" class=\\\"CitationRef\\\"\\u003e8\\u003c/span\\u003e]. In comparison with the EDLCs, generally pseudo capacitor exhibits superior specific capacitance and power density, nevertheless the lower conductivity and long-term cycle stability are greatly influences on their device performance in the real time practical applications [\\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e9\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR10\\\" class=\\\"CitationRef\\\"\\u003e10\\u003c/span\\u003e]. Thus, many efforts have been paid to fabricate of the composites that can rendered improved charge density and stability in long cycles of operations.\\u003c/p\\u003e \\u003cp\\u003ePresently, transition metal oxides (TMOs) nanocomposites have gained much interest for researchers across the globe to utilize as an active electrode material for supercapacitors and battery applications owing to their superior redox properties, large specific capacitance, ecologically friendly nature, and easy accessibility [\\u003cspan additionalcitationids=\\\"CR12\\\" citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e11\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR13\\\" class=\\\"CitationRef\\\"\\u003e13\\u003c/span\\u003e]. Amid the many TMOs, cobalt-iron oxide is deliberated a most suitable electrode materials for supercapacitor practical relevance\\u0026rsquo;s due to their many oxidations state (Co\\u003csup\\u003e3+\\u003c/sup\\u003e/Co\\u003csup\\u003e2+\\u003c/sup\\u003e), superior theoretical capacity, tuneable electrochemical properties, and good level of thermal stability [\\u003cspan citationid=\\\"CR14\\\" class=\\\"CitationRef\\\"\\u003e14\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR15\\\" class=\\\"CitationRef\\\"\\u003e15\\u003c/span\\u003e]. Therefore, in majority of the cases reported in the earlier literature, the value of the specific capacity recorded for cobalt-iron oxide ferrite electrode is extremely lower in compare to theoretical calculated capacity value. At present, it is great challenge to fabricate a novel nano ferrites composite that is treated as preferable material for gain higher electrochemical performance [\\u003cspan citationid=\\\"CR16\\\" class=\\\"CitationRef\\\"\\u003e16\\u003c/span\\u003e].\\u003c/p\\u003e \\u003cp\\u003eThe perovskite-based ferrite nanocomposites were very prominence in the studies on energy storage applications because of their originality in their structure as well properties. This kind of geometry has been greatly examined in different applications in gas sensors, solar cells, electronics, and in supercapacitors [\\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e17\\u003c/span\\u003e]. The chemical formula we used to represent the perovskite geometry is ABO\\u003csub\\u003e3\\u003c/sub\\u003e, here A and B shows the rare earth (RE) sites like lanthanum, samarium, caesium, neodymium, and yttrium etc and transition metals like iron, cobalt, nickel, and cobalt in order [\\u003cspan citationid=\\\"CR18\\\" class=\\\"CitationRef\\\"\\u003e18\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR19\\\" class=\\\"CitationRef\\\"\\u003e19\\u003c/span\\u003e]. The plenty of vacancies in oxygen lattice in crystal structure play a vital role in the electric charge storage kinetics mechanism [\\u003cspan citationid=\\\"CR20\\\" class=\\\"CitationRef\\\"\\u003e20\\u003c/span\\u003e]. Recently, rare-earth metal oxide materials have been interested notable attention because of their exceptional features in variable electrochemical sites [\\u003cspan citationid=\\\"CR21\\\" class=\\\"CitationRef\\\"\\u003e21\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR22\\\" class=\\\"CitationRef\\\"\\u003e22\\u003c/span\\u003e].\\u003c/p\\u003e \\u003cp\\u003eRecently, \\u003cb\\u003eShyamli Ashok C\\u003c/b\\u003e et al. synthesized Co\\u003csub\\u003ex\\u003c/sub\\u003eNi\\u003csub\\u003e1\\u0026minus;x\\u003c/sub\\u003eO ferrites composites of variable concentration of cobalt and nickel NPs via solution combustion method. The synthesized ferrite NPs were characterized through different analytical and spectroscopic methods. In these studies, they found that doping of NPs into the ferrites, the electrochemical properties were significantly improved. The Co\\u003csub\\u003ex\\u003c/sub\\u003eNi\\u003csub\\u003e1\\u0026minus;x\\u003c/sub\\u003eO composites at 0.5A/g exhibited highest specific capacity about 325 C/kg with superior level of capability, improved charging and discharging and stability in long cycles [\\u003cspan citationid=\\\"CR23\\\" class=\\\"CitationRef\\\"\\u003e23\\u003c/span\\u003e]. \\u003cb\\u003eBablu Mordina\\u003c/b\\u003e et al. fabricated NiFe\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e ferrites composite for possible energy storage applications. The ferrite composites were prepared via co-precipitation technique and performed XRD analysis for the single-phase confirmation in the synthesized ferrite composites. The specific capacity was found to be 400 C/g for highest NPs doping sample at current density of 2.5 A/g. The energy density and power density of 27.71 Wh/kg and 14.49 kW/kg are attained at 1 and 20 A/g current density values respectively. This research group drawn the conclusion that, by doping suitable rare earth NPs into the NiFe\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e ferrites, the electrochemical properties significantly improved could be utilized as an electrode material for the fabrication of supercapacitors [\\u003cspan citationid=\\\"CR24\\\" class=\\\"CitationRef\\\"\\u003e24\\u003c/span\\u003e]. \\u003cb\\u003eVidyadevi A. Jundale\\u003c/b\\u003e et al. prepared cobalt ferrite thin films electrode material by using chemical spray pyrolysis method for supercapacitor application. The prepared CoFe\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e thin films were characterized via SEM, UV-visible and XRD for morphological and confirmation cubical phases in the synthesized ferrites samples. The specific capacitance of the synthesized CoFe\\u003csub\\u003e2\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e thin film was recorded to be 369 F/g at a scan rate of 2 mVs\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e. This group confirms that, the prepared electrode material is pseudocapacitive nature with quick charging and discharging rates. The higher NPs doping ferrite thin film shows that improved power density and energy density in the order of 27.14 Wh/kg and 28.74 kW/kg respectively at constant current density of 2 mA/g [\\u003cspan citationid=\\\"CR25\\\" class=\\\"CitationRef\\\"\\u003e25\\u003c/span\\u003e].\\u003c/p\\u003e \\u003cp\\u003eThe above-mentioned previously published literatures motivated us to carry out the present studies in cobalt-iron-oxide ferrite system for possible utilization of electrode materials in supercapacitor. In the presented research work, we are interested to enhance the electrochemical performance of CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e ferrite by inclusion of samarium NPs. We employed very simple, low cost and one step solution combustion method to synthesis samarium (RE) doped cobalt-iron-oxide ferrites composites. The other methods such as hydrothermal, chemical vapor deposition, and electrodeposition that need improved instruments and operating condition, but the solution combustion technique could be manageable method to gain porous nature of ferrite NPs [\\u003cspan citationid=\\\"CR26\\\" class=\\\"CitationRef\\\"\\u003e26\\u003c/span\\u003e].\\u003c/p\\u003e \\u003cp\\u003eIn the presented work, we have systematically demonstrated a simple method used to fabricate high performance samarium doped CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e ferrite composites electrode materials for supercapacitor applications prepared via solution combustion method. We have systematically studied the surface morphology, structural and electrochemical properties of samarium doped CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e ferrite and effects of samarium dopant concentration in the characteristics features of CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e composites was investigated in detail. We have seen that inclusion of samarium NPs in to the CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e ferrite, there is a significantly improved the electrochemical features of CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e ferrite composites and excellent electrochemical work function was shown by the CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) composite as they have given specific capacity of 850 F/g at constant 50 mV/s, this value almost three folds larger than the pure CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.0) ferrite sample. However, the prepared CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) composite sample exhibited 98% of capacitance retention even after the running of 5000 cycles of operations. By measuring the parameters like cyclic voltammetry, prolonged charging and discharging cycles and impedance spectroscopy results were employed to judge the performance of the electrode materials tested for the supercapacitors applications and all these parameters represented by using appropriate mathematical equations [\\u003cspan citationid=\\\"CR27\\\" class=\\\"CitationRef\\\"\\u003e27\\u003c/span\\u003e].\\u003c/p\\u003e \\u003cp\\u003eHence, this current research work suggests a simple method to synthesized more porous samarium doped CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e ferrites in search of excellent electrode materials based on the hybrid transition metal oxides (TMOs) for new generation supercapacitors. Intend, this presented study will guide the researchers and device technocrats across the world, how the features of the electrode materials could be recognized and their superior electrochemical performance should be offered by prudent utilization of proper electrode materials for supercapacitor application.\\u003c/p\\u003e\"},{\"header\":\"2. Experimental\",\"content\":\"\\u003cdiv id=\\\"Sec3\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003e2.1. Materials and Methods:\\u003c/h2\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec4\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003e2.2 Synthesis of samarium doped cobalt iron ferrites nanocomposite:\\u003c/h2\\u003e \\u003cp\\u003eThe routine solution combustion method was utilized to prepare CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.0, 0.050, 0.075 and 0.1) ferrite NPs. The chemicals like cobalt nitrate hexahydrate [Co (NO3)2.6H2O], ferrous based nitrate nano hydrate [Fe (NO3)3.9H2O], samarium nitrate [Sm (NO3)3], urea [CO(NH2)2] and glucose [C6H12O6] are procured from Sigma Aldrich (India). During preparation, the metal nitrate powder salt act as an oxidizing agent while urea and glucose behave as reducing agents during the synthesis process. In 500 mL round bottom conical flask was taken stoichiometric ratio of two oxidising and reducing agent materials are mixed thoroughly and added deionized water into the beaker to achieve the superior quality of ferrite NPs. The achieve highly pure nanocomposite solution was uniformly mixed up to a time duration of 10 hours with the help of magnetic stirrer and rotation speed was maintained about 2000 rpm to achieve homogenously dispersed nano ferrite solution. The prepared nano ferrite solution was shifted into the muffle furnace and kept at a temperature of nearly 500 \\u003csup\\u003eo\\u003c/sup\\u003eC. The fine mixed nano ferrite solution was permitted to boil at high temperature to eliminate all types of poisonous gases and rest mass of nano ferrite was dried to achieve the final yield product [\\u003cspan citationid=\\\"CR28\\\" class=\\\"CitationRef\\\"\\u003e28\\u003c/span\\u003e]. The detailed flow chart of synthesis method of the novel CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e ferrite NPs was shown in the Figure. 1. The product of ferrite nano powder was attained in the type of black puffy colured and light foamy in mass. This nano ferrite powder was shifted into the agate mortar, and fine grinded to achieve fine ferrite nano powder. Therefore, the synthesized ferrite NPs powder was utilized to execute different analytical and spectroscopic characterization. To measure electrochemical parameters, we have prepared the ferrite composite electrode on nickel mesh towards the testing of supercapacitors applications.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec5\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003e2.3 Preparation of electrode material for supercapacitor testing:\\u003c/h2\\u003e \\u003cp\\u003eTo fabricate CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e as working electrode, 80% CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e nano ferrite powder, 15% of pure graphene powder and 5% of PTFE solution which act as a binder was well grinded in an agate motor for a duration of 1 hour to achieve a homogeneous thin sheet. This prepared sheet was pasted over the nickel mesh. After the coated with the paste, these pasted electrodes were compressed at 20 MPa for the duration of 5 minutes to ensure the electrical contact between the nickel mesh and the active material. The back side of the electrode and the contact wire was tightly insulated by employing a Teflon tape to achieve an electrode with an active area for the measurements about 2 cm \\u0026times;1 cm and prior use, it was immersed in the 6.0 M KOH solution for a duration of 60 minutes to achieve good level of electrode contact with the electrolyte.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec6\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003e2.4 Materials Characterization:\\u003c/h2\\u003e \\u003cp\\u003eThe exterior morphology of the synthesized CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.0, 0.050, 0.075 and 0.1) ferrite nanoparticles (NPs) were performed by using scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) (Ultra Scan 60: Japan). The nano sized morphology in the prepared ferrite composite was recorded by using transmission electron microscope (TEM) (Thermofisher TEM TALOS with CMOS camera system). The creation of mono-phase crystal structure in the prepared nano ferrite composite samples were tested by employing powder X-ray diffraction method (XR Ultra Dynamics-400, UK) at the region 2Ɵ = 20\\u003csup\\u003eo\\u003c/sup\\u003e to 80\\u003csup\\u003eo\\u003c/sup\\u003e Cu Kα (λ\\u0026thinsp;=\\u0026thinsp;1.5418 \\u0026Aring;). The existence of different chemical groups and variable stretching frequencies present in the synthesized nano ferrites composite were inspected via Fourier Transform Infrared Spectroscopy (FTIR) (Thermo Nicolet, Avatar 370 -India). The optical absorption features of prepared ferrite composites were achieved by employing UV\\u0026ndash;visible spectrometry (Perkin Elmer-Canada) in the range of 300 nm\\u0026ndash;600 nm. The cyclic voltametric analysis was executed on a CHI604E potentiostat electrochemical analyser with a three-electrode assembly, which comprises of CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e electrode, platinum wire, and Ag/AgCl as accordingly working, counter, and reference electrodes correspondingly and the electrolyte solution was taken as 6.0 M KOH solution. The applied potential range was 0.2 V to 0.6 V (towards Ag/ AgCl electrode) and the standard scanning rate was set in the order of 5 mV/s, 10 mV/s, 15 mV/s, 20 mV/s and 25 mV/s, for the Galvanostat charge-discharge measurement at a current density of 5 Ag\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e inside the potential window of 0.0V- 0.6V versus Ag/AgCl. In addition to above said parameters, the AC amplitude of 5 mV and frequency rangime of 1 Hz to 1 MHz we applied for electrochemical impedance spectroscopy (EIS) tests were also recorded.\\u003c/p\\u003e \\u003c/div\\u003e\"},{\"header\":\"3. Results and discussion\",\"content\":\"\\u003cdiv id=\\\"Sec8\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003e3.1 Scanning electron microscope and EDS analysis:\\u003c/h2\\u003e \\u003cp\\u003eThe scanning electron microscopy technique used to characterize the surface morphologies of samarium doped cobalt-iron ferrite composites. Figure. 2 (a-d) shows the SEM micrographs of CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.0, 0.050, 0.075 and 0.1) ferrite NPs. The SEM images displays a flake type morphology with more porous structure [\\u003cspan citationid=\\\"CR29\\\" class=\\\"CitationRef\\\"\\u003e29\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR30\\\" class=\\\"CitationRef\\\"\\u003e30\\u003c/span\\u003e]. These large pores are generated because of liberation of more gases at the time combustion process. The undoped ferrite sample (x\\u0026thinsp;=\\u0026thinsp;0.0) shows smooth and homogenous without formation of much pores in its morphology. By inclusion of rare earth (RE) like samarium NPs into the cobalt-iron ferrites, morphology of composites was drastically improved, which is witnessed for the superior advanced applications in energy storage devices. It could be observed that, amid the prepared ferrite samples, CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) shows more porous morphology behaviour with large open pores, which is facilitate more and more active areas. However, when the doping percentage of samarium was enhanced to x\\u0026thinsp;=\\u0026thinsp;0.1 into the CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, the particle tends to be highly agglomerate which is reflects from the SEM micrograph. The optimized concentration of x\\u0026thinsp;=\\u0026thinsp;0.1 of samarium NPs doped in cobalt-iron ferrite shows highly efficient electrochemical performance. \\u0026ldquo;The energy dispersive X-ray spectroscopy (EDS) analysis\\u0026rdquo; was carried out to prove the variable elemental composition exists in the prepared CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e ferrite composite. Figure. 3 (a and b) shows the EDS spectra of x\\u0026thinsp;=\\u0026thinsp;0.0 and x\\u0026thinsp;=\\u0026thinsp;0.1 ferrite composite. The EDS tests of the synthesized ferrites sample was done in the range of 0.2 keV to 14 keV. From the Figure.3 (a) for x\\u0026thinsp;=\\u0026thinsp;0.0 ferrite sample, the prime element such as cobalt, iron and oxygen were existed. At the same time in Figure.3 (b) ferrite sample, the prime elements such as samarium, cobalt, iron, and oxygen were present. By using EDS method, determination of elemental composition is well obeyed with the theoretically determined stoichiometry values, both the values were elucidated in the Table.1.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec9\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003e3.2 Transmission electron microscope (TEM) analysis:\\u003c/h2\\u003e \\u003cp\\u003eThe \\u0026ldquo;transmission electron microscopy (TEM) analysis\\u0026rdquo; was done for the synthesized ferrite samples to prove the nanostructure features in the samples. Figure.4(a) shows the low magnification TEM image of CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) composite. The NPs are approximately flake type morphology with more porous structure [\\u003cspan citationid=\\\"CR31\\\" class=\\\"CitationRef\\\"\\u003e31\\u003c/span\\u003e]. These large pores are generated because of liberation of more gases at the time combustion process. The mean average particle dimension of 38\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;4 nm which is good agreed with the average particle size (40\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;5nm) calculated by using Sherrer equation. The SAED distribution structure of CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) composite was illustrated in the Figure.4(b). It comprises of many concentric circular rings with bright spots of crystallites shows the polycrystalline features of spinel crystal geometry ferrites NPs with high degree of crystallinity. The maximum bright ring generated because of the diffraction from the crystal plane (311). The rings inside the bright circular rings could be described for diffraction occur from the crystal plane (220) and at the same time exterior circular rings could be nominated to the diffraction effects from the crystalline planes (400), (422), (511) and (440) respectively. The results obtained from TEM and SAED pattern clearly validate that Sm\\u003csup\\u003e3+\\u003c/sup\\u003e NPs were homogenously distributed in the Co-Fe-O\\u003csub\\u003e4\\u003c/sub\\u003e ferrites structure without any formation of secondary phases [\\u003cspan citationid=\\\"CR32\\\" class=\\\"CitationRef\\\"\\u003e32\\u003c/span\\u003e].\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec10\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003e3.3 X-ray diffraction analysis (XRD):\\u003c/h2\\u003e \\u003cp\\u003eThe powder XRD pattern of the prepared CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.0, 0.050, 0.075 and 0.1) NPs recorded at ambient temperature were elucidated in the Figure.5. The recorded XRD spectra shows prominent peaks very close to the planes (100) (101) (200) (210) (211) (300) (311) (401) and (411) shows mono phase features of cubic spinel ferrite composite with well match with the standard JCPDS: Card number: 21\\u0026ndash;1076). Almost all-important peaks were existed in higher NPs concentration doping Co-Fe-O\\u003csub\\u003e4\\u003c/sub\\u003e ferrite composite. The XRD spectra shows the formation of Fd3m ionic space and well formation of single phase in the spinel cubical shape. The more ionic radius of Sm\\u003csup\\u003e3+\\u003c/sup\\u003e (1.05 A˚) which is well associated with the radius of Fe\\u003csup\\u003e3+\\u003c/sup\\u003e (0.64 A˚), these major changes might be believed that the inclusion of positive charge substituted by iron in cobalt-based ferrite nanocomposite. The inclusion of RE like samarium NPs into Co-Fe-O4 ferrite, there is no such major modification was observed in the crystal structure. To estimate the crystal size, we employed Scherrer\\u0026rsquo;s equation [\\u003cspan citationid=\\\"CR33\\\" class=\\\"CitationRef\\\"\\u003e33\\u003c/span\\u003e] which is well agreement with grain size determined via SEM analysis.\\u003cdiv id=\\\"Equa\\\" class=\\\"Equation\\\"\\u003e\\u003cdiv format=\\\"TEX\\\" class=\\\"mathdisplay\\\" id=\\\"FileID_Equa\\\" name=\\\"EquationSource\\\"\\u003e\\n$$D=\\\\frac{k\\\\lambda }{\\\\beta cos\\\\theta }$$\\u003c/div\\u003e\\u003c/div\\u003e\\u003c/p\\u003e \\u003cp\\u003eIn the above equation, D indicates the crystallite size, k be the dimensional geometry factor which is nearly 0.9 for round shaped particles, λ be the wavelength of X-ray utilized, β is the FWHM intensity, and θ be the diffraction angle. The determined crystallite size through XRD analysis is nearly in order of 40 nm. It is very curious to observe that the value of lattice parameter and lattice volume was slight changes in doped NPs ferrite composite. The drop in the lattice value due to variation in the ionic radius that proved the dopant blend on substituted lattice site. From the XRD spectra it was clearly demonstrated that, there is marginal change in crystal lattice parameter of the CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e ferrite composite owing to cationic modification in entire crystal structure. In particular, the crystallite size exhibits the same behaviour and reduction considerably when the inclusion of samarium NPs into the cobalt-iron ferrites.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec11\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003e3.4 Fourier transform infrared spectroscopy (FTIR):\\u003c/h2\\u003e \\u003cp\\u003eThe consequences of doping by using samarium (RE) in cobalt-iron oxide ferrite composite over the structure and its surface morphology was measured through spectroscopic method. The trend of FTIR spectra of CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.0, 0.050, 0.075 and 0.1) ferrite NPs is shown in the Figure.6. The major peaks around 606 and 660 cm\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e stretching vibrations may be due to the vibration of Fe-O and Co-O bonds near to octahedral and tetrahedral areas of ferrite composite. The strong lattice vibrations near at the stretching frequencies of 440 and 808cm\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e are owing to symmetric lattice vibration of the samarium and cobalt metal NPs in their localized areas [\\u003cspan citationid=\\\"CR34\\\" class=\\\"CitationRef\\\"\\u003e34\\u003c/span\\u003e]. The major lattice vibration of peak around the stretching frequency 3500 cm\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e might be due to O-H lattice vibration arises due to the absorbed water molecules in the ferrite composite. The lattice vibration of stretching frequencies nearly 1120, 1153 and 1380 cm\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e are the characteristic vibration of cobalt-iron oxide ferrites. Hence, the formation of cations with different ionic radius leads to the creation of real crystals. In particular, the oxygen atoms are liberated from their normal sites to create the empty site for the cations with the larger ionic radius [\\u003cspan citationid=\\\"CR35\\\" class=\\\"CitationRef\\\"\\u003e35\\u003c/span\\u003e]. This examination was good agreements with the XRD analysis for the creation of single phases before and after the inclusion of samarium NPs into the CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e composite.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec12\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003e3.5 UV-Visible spectroscopic analysis:\\u003c/h2\\u003e \\u003cp\\u003eUV-visible spectroscopy technique largely utilized technique for optical characterization in majority of the ferrite based composite materials. The UV-visible spectra of CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.0, 0.050, 0.075 and 0.1) NPs were recorded in wavelength range of 200nm to 800nm are illustrated in the Figure.7. By enhancing the concentration of samarium NPs into the CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e, the intensity of the peak marginally increases. The major absorption peaks show the truth that photons are largely absorbed approximately 600 nm, this wavelength region comes under the range of visible area of the EM spectrum. The prime reason in the change of UV\\u0026ndash;visible spectra of the ferrite composite is owing to its surface morphology and grain size present at the larger concentration of samarium treated cobalt-iron oxide ferrite sample. It was noticed from the UV\\u0026ndash;visible spectra, the more energy transition can be owing to the π-π* ferrite composite [\\u003cspan citationid=\\\"CR36\\\" class=\\\"CitationRef\\\"\\u003e36\\u003c/span\\u003e]. In the UV\\u0026ndash;visible spectra the band commencing from the 700 nm have been assigned as free carrier tail. We can easily interfere from UV-visible spectra, the intensity of the peak gradually increasing the percentage of samarium NPs into the cobalt-iron-oxide ferrite. We observed form UV-visible absorption spectra, by enhancing the concentration of NPs into the cobalt-iron-oxide ferrite, the peaks intensity gradually improved. This improved intensity of the peak shows that the good level of interaction between samarium (RE) and iron-nickel oxide ferrite.\\u003c/p\\u003e \\u003c/div\\u003e\"},{\"header\":\"4. Electrochemical characterizations\",\"content\":\"\\u003cdiv id=\\\"Sec14\\\" class=\\\"Section2\\\"\\u003e\\n \\u003ch2\\u003e\\u003cstrong\\u003e4.1\\u003c/strong\\u003e. \\u003cstrong\\u003eCyclic voltammetry (CV) studies\\u003c/strong\\u003e:\\u003c/h2\\u003e\\n \\u003cp\\u003eTo study the charge storage applications of the synthesized CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e nanocomposite ferrites, cyclic voltammetry (CV) measurement was done by using three electrode assembly employing 6 M KOH as the electrolyte solution. Figure.8 shows the variation of cyclic voltammetry CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.0, 0.050, 0.075 and 0.1) nanocomposite ferrites with operating window of \\u0026minus;\\u0026thinsp;0.2 to 0.8 V. The CV curves of all the synthesized ferrite samples shows a couple of major redox peaks which exhibit the faradaic features of the material. This is relatively variable from the CV curve shows by electrical two-layer capacitance features, which is generally very near to perfect rectangular geometry [\\u003cspan class=\\\"CitationRef\\\"\\u003e37\\u003c/span\\u003e\\u0026ndash;\\u003cspan class=\\\"CitationRef\\\"\\u003e38\\u003c/span\\u003e]. It is observed from CV curve, the electrode material shows unique features like the anodic peak rises to more potential and at the same time the cathodic peak moved to lower potential value which reflects the fact that good level of electrochemical reversibility [\\u003cspan class=\\\"CitationRef\\\"\\u003e39\\u003c/span\\u003e]. Fascinatingly, at lower value scan rates the pores distribution over the cathode are well present for the electrolyte particles and therefore improving the capacitance behaviour of the ferrite composite. In distinction, the pores over the electrode could be easily available for the electrolyte ions, which effects leads to the improved capacitance behaviour at lesser scan rates. Additionally, as we enhance the potential scan rate, there is a small shift of the oxidation peak in the direction of higher positive potential and the reduction peak near to negative direction. These effects might be due to the uncompensated resistance and polarization mechanism in the region of more scan rate [\\u003cspan class=\\\"CitationRef\\\"\\u003e40\\u003c/span\\u003e]. The variation of CV curves for CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) ferrite composite at variable scan rate were illustrated in the Figure.8 (b). The CV curves shows that approximately quasi rectangular geometry for variable scan rates like (5 mV/s to 250 mV/s) shows a perfect capacitive feature of the ferrite composite owing to more reversible redox chemical reactions of CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e and the exterior surface electro adsorption of samarium NPs. The value of the specific capacitance (C\\u003csub\\u003esp\\u003c/sub\\u003e) for the prepared CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.0, 0.050, 0.075 and 0.1) ferrite composites were calculated by using the equation based on the CV as follows.\\u003c/p\\u003e\\n \\u003cdiv id=\\\"Equb\\\" class=\\\"Equation\\\"\\u003e\\n \\u003cdiv class=\\\"mathdisplay\\\" id=\\\"FileID_Equb\\\" name=\\\"EquationSource\\\"\\u003e$${C}_{sp}=\\\\frac{S}{m\\\\times \\\\delta V\\\\times K}$$\\u003c/div\\u003e\\n \\u003c/div\\u003e\\n \\u003cp\\u003eIn the above equation S indicates area under the CV curves, m be the weight of ferrite deposited over the electrode material, \\u0026delta;V be the voltage window and K be the variable scan rate.\\u003c/p\\u003e\\n \\u003cp\\u003eOne of the important parameters used to characterized the active surface area available in the electrode material is voltametric charge distribution (q*) to judge the superior performance for supercapacitor applications [\\u003cspan class=\\\"CitationRef\\\"\\u003e41\\u003c/span\\u003e]. Generally, the charges present in both interior and exterior surfaces will donates to the bulk charges stored in an active electrode material. Hence, the total charges stored in an electrode material can be represented by using the equation.\\u003c/p\\u003e\\n \\u003cp\\u003e\\u003cimg src=\\\"data:image/png;base64,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\\\"\\u003e\\u003c/p\\u003e\\n \\u003cp\\u003eThe value of the volumetric charges (q*) could be determined by applying integration to the CV curves at variable scan rates and dividing with the geometrical area of the electrode material. From the Figure.9 (a) and (b) it is very clearly observed that both the values of q* and 1/q* were linearly varies with the V\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1/2\\u003c/sup\\u003e and V\\u003csup\\u003e1/2\\u003c/sup\\u003e in order with respect different weight percentage of samarium NPs into the Co-Fe-O\\u003csub\\u003e4\\u003c/sub\\u003e ferrite sample. This trend might be owing to the irreversible redox mechanism and ohmic drops leads to the more resistance of samarium doped Co-Fe-O\\u003csub\\u003e4\\u003c/sub\\u003e ferrite composites. The extrapolation of charge q* with respect to V\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1/2\\u003c/sup\\u003e =0 (Figure. 9a), which signifies q*\\u003csub\\u003eout\\u003c/sub\\u003e resemble easily available to outer charges at the same time the extrapolation of 1/q* as shown in (Figure. 2b) which gives the q*\\u003csub\\u003etotal\\u003c/sub\\u003e. The linear trends of both q* and 1/q* were greatly suggests that the enhancement in the more charge gathering in the ferrite nanocomposite [\\u003cspan class=\\\"CitationRef\\\"\\u003e42\\u003c/span\\u003e]. The more charge accumulation in the ferrite composite samples exhibit a major dependence over the doping of samarium (RE) NPs into the Co-Fe-O\\u003csub\\u003e4\\u003c/sub\\u003e nanocomposite ferrite. The enhancement in the charge accumulation in the ferrite nanocomposites were ascends primarily due to the enhancement in the active surface area as well as pores size spreading owing to the inclusion of samarium NPs into the host Co-Fe-O\\u003csub\\u003e4\\u003c/sub\\u003e nanocomposite ferrite as clear from SEM micrographs. Further, to interpret the synergetic effects of samarium doping into the Co-Fe-O\\u003csub\\u003e4\\u003c/sub\\u003e ferrite composite over the active surface area and pore size, we have done the BET analysis of all synthesized ferrite composites sample and obtained data is given in the Table.2. The data obtained from BET analysis we conform that by the doping of samarium NPs into the Co-Fe-O4 ferrite composites, there is significant improvements in the surface area, pore size and volume of the pore in compare to the undoped ferrite sample, these modification in the ferrite nanocomposites play very crucial role in the improvements in the electrochemical performance of the ferrites-based nanocomposites.\\u003c/p\\u003e\\n\\u003c/div\\u003e\\n\\u003cdiv id=\\\"Sec15\\\" class=\\\"Section2\\\"\\u003e\\n \\u003ch2\\u003e4.2 Electrochemical impedance spectroscopy (EIS) studies:\\u003c/h2\\u003e\\n \\u003cp\\u003eThe capacitive features of pure CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e and CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.0, 0.050, 0.075 and 0.1) ferrite composites are examined via \\u0026ldquo;electrochemical impedance spectroscopy\\u0026rdquo; (EIS) by recording charge transfer resistance (R\\u003csub\\u003ect\\u003c/sub\\u003e) and equivalent resistance in the series combination (R\\u003csub\\u003eeq\\u003c/sub\\u003e). Figure.10 shows the Nyquist plots of CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.0, 0.050, 0.075 and 0.1) ferrite composites are recorded at 1Hz to 1MHz frequency region exhibit nearly linear behaviour at the lower frequency\\u0026rsquo;s region, this kind of behaviour indicates that the prepared electrode material by exactly capacitive nature [\\u003cspan class=\\\"CitationRef\\\"\\u003e43\\u003c/span\\u003e].The EIS features of the ferrite composites from the Nyquist plots over the total applied frequencies region also exhibit fascinating features of this kind of material as a higher performance electrode because of lower R\\u003csub\\u003ect\\u003c/sub\\u003e values of CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) ferrite composite. From the Nyquist plots one can easily interfered that the geometrical resistance value of the synthesized ferrite composite reduces considerable at the same time the capacitance behaviour enhanced with inclusion of samarium NPs into the Co-Fe-O\\u003csub\\u003e4\\u003c/sub\\u003e ferrites. The inclusion of Sm\\u003csup\\u003e3+\\u003c/sup\\u003e NPs inside the Co-Fe-O\\u003csub\\u003e4\\u003c/sub\\u003e ferrites is believed to enhances the active surface area as well as pore size distribution that led to the deduction in the interior resistance of the ferrite composites. The lower R\\u003csub\\u003ect\\u003c/sub\\u003e value of CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) is because of the exitance of many conductive pathways and larger diffusivity of the electrolyte ions present in the tested sample [\\u003cspan class=\\\"CitationRef\\\"\\u003e44\\u003c/span\\u003e]. From the Nyquist plots we can conclude that the higher concentration samarium NPs doping into Co-Fe-O\\u003csub\\u003e4\\u003c/sub\\u003e ferrite with enhanced electrical conductivity and almost linear variation of impedance at very lower frequencies regime, hence conclude the super capacitive features of the synthesized of electrode material for supercapacitor applications.\\u003c/p\\u003e\\n\\u003c/div\\u003e\\n\\u003cdiv id=\\\"Sec16\\\" class=\\\"Section2\\\"\\u003e\\n \\u003ch2\\u003e4.3 Galvanostatic charge discharge (GCD):\\u003c/h2\\u003e\\n \\u003cp\\u003eTo examine the electrochemical features of the as synthesized CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.0, 0.050, 0.075 and 0.1) ferrite composites samples, we have carried out the charging and discharging tests were done in 6 M KOH high concentrated electrolyte solution. The measurements were done at the potential range of 0 to 0.6 V at constant current density of 50 A/g is illustrated in the Figure.11 (a). It is very clearly visible from the plots that there are two well visible areas in the plots. The region starting from 0 to 0.55 V exhibits the two-layer capacitive features here there is an almost linear trend of potential with respect to time. The Redox process of the synthesized ferrite samples was shown by the sloped trend of applied potential with a function of time in the region of 0.36 to 0.54 V. During the cycling process, there is existence of Faradaic reactions was evident that voltage plateau at this operated voltage. Generally, the plateau potential value of charging mechanism is much higher than that of discharging mechanism. These effects might be due to the change in kinetics values of the redox chemical reaction at the time of charging and discharging mechanism which turn into electrode polarization [\\u003cspan class=\\\"CitationRef\\\"\\u003e45\\u003c/span\\u003e]. We can draw the conclusion from GCD profiles, the charge storage in CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e composites is primarily because of the Faradaic mechanism, which is well correlated with the CV tests. Amid of the prepared ferrite sample CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) composite sample exhibits more discharging time in compare to other prepared ferrites samples, which reflects the facts that larger specific capacity.\\u003c/p\\u003e\\n \\u003cp\\u003eFigure.11 (b and c) shows the Galvanostatic charge\\u0026ndash;discharge (GCD) cycles for CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) composite for first cycle and 2000 cycles respectively. The geometry of the GCD curves is associated to the pseudocapacitive behaviour of the prepared electrodes materials [\\u003cspan class=\\\"CitationRef\\\"\\u003e46\\u003c/span\\u003e]. The specific capacitance values during charging and discharging process could be determined by employing the equation [\\u003cspan class=\\\"CitationRef\\\"\\u003e46\\u003c/span\\u003e].\\u003c/p\\u003e\\n \\u003cdiv id=\\\"Equc\\\" class=\\\"Equation\\\"\\u003e\\n \\u003cdiv class=\\\"mathdisplay\\\" id=\\\"FileID_Equc\\\" name=\\\"EquationSource\\\"\\u003e$${C}_{sp}=\\\\frac{i dt}{m ({v}_{f}-{v}_{i})}$$\\u003c/div\\u003e\\n \\u003c/div\\u003e\\n \\u003cp\\u003eIn the above equation \\u0026ldquo;i\\u0026rdquo; be the subjected current, dt be the discharged time, m be the mass of ferrite composite coated on to the electrode and (V\\u003csub\\u003ef\\u003c/sub\\u003e\\u0026minus;V\\u003csub\\u003ei\\u003c/sub\\u003e) be the working potential window values. By inclusion of rare earth metal like samarium into the Co-Fe-O\\u003csub\\u003e4\\u003c/sub\\u003e ferrite the potential values are significantly improved, and noticeable coulombic efficiency was noticed from GCD plots for CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) nanocomposite with retention about 98% even after the 2000 cycles of operation. This result indicates that improved efficiency of the higher concentration samarium NPs doped Co-Fe-O\\u003csub\\u003e4\\u003c/sub\\u003e ferrite composites.\\u003c/p\\u003e\\n \\u003cp\\u003eThe variation of specific capacitance with a function of current densities were shown in the Figure.12 (a). Both the parameters like discharge time and specific capacity reduces sharply with increase of current densities. This kind of trend might be due to non-availability of time for the electrolytes ions to migrates totally inside the electrode at the region of Faradaic chemical reactions take place. As these consequences some area of the electrode surface unavailable to the electrolyte\\u0026rsquo;s ions at the region of higher current [\\u003cspan class=\\\"CitationRef\\\"\\u003e47\\u003c/span\\u003e]. Among the prepared ferrite samples CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) composites exhibit 98% specific capacity retention value demonstrates good electrode material for supercapacitor applications.\\u003c/p\\u003e\\n \\u003cp\\u003eFurthermore, we have carried out the cycling stability tests for CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) composites electrode material by revising the CV rotations over the scan rate of 250 mV/s in 6 M KOH electrolytic solution for a duration of 5000 times. The variation of capacitance retention percentage with a function of subjected cycle numbers for CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) composite was illustrated in the Figure.12 (b). It is very clear from the plots the 98% of the specific capacity was remain stable even after the end of 5000 cycles of operations. Initially, it was found that there was a marginal reduction in the specific capacity up to the 2000 cycles of operation and there after it turn to nearly stable and moved to 98% at the end of 5000 cycles of operations [\\u003cspan class=\\\"CitationRef\\\"\\u003e48\\u003c/span\\u003e]. In our presented research results we confirmed that CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) composite electrode material exhibits fabulous cycling performance for long cycles of operations.\\u003c/p\\u003e\\n \\u003cp\\u003eThe trend of energy density with a function of power density of CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.0, 0.050, 0.075 and 0.1) ferrite composites studied at room temperature which results in the Ragone plots is shown in the Figure.13. The energy density and power density of the synthesized ferrites are determined by using the equations.\\u003c/p\\u003e\\n \\u003cp\\u003e\\u003cimg 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\\\"\\u003e\\u003c/p\\u003e\\n \\u003cp\\u003eThe lowest energy density for pure CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.0) ferrite sample was recorded nearly equal to 14 Wh/kg at a power density of 300 Wh/kg, however CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) ferrite composite exhibit outstanding enhancement in the power density about 30.16 Wh/kg at an applied power density of 400 Wh/kg. The higher concentration NPs ferrite composite shows improved energy density values with respect to the power density, which reflects the facts that the superior capacitive behaviour of the ferrite composites [\\u003cspan class=\\\"CitationRef\\\"\\u003e49\\u003c/span\\u003e\\u0026ndash;\\u003cspan class=\\\"CitationRef\\\"\\u003e50\\u003c/span\\u003e]. The enhanced specific capacitance, specific capacitance retention, the energy and power density of the CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) ferrite composite exhibit fabulous performance in compare to recent literature published on cobalt-iron-oxide ferrites [\\u003cspan class=\\\"CitationRef\\\"\\u003e51\\u003c/span\\u003e]. Therefore, by doping method utilised in this current research work plays very prominent role in the enhancement of supercapacitor properties.\\u003c/p\\u003e\\n\\u003c/div\\u003e\"},{\"header\":\"5. Conclusion\",\"content\":\"\\u003cp\\u003eIn conclusion, we utilized a simple, less expensive, very fast, one step method of solution combustion technique used to synthesize samarium doped cobalt-iron oxide ferrites composites. The Sm\\u003csup\\u003e3+\\u003c/sup\\u003e and Fe\\u003csup\\u003e3+\\u003c/sup\\u003e NPs were effectively doped at variable concentrations into the cobalt oxide ferrite system, without altering the phase of pure cobalt oxide ferrite. The presence of any kind of secondary peaks before and after doping of NPs as well as creation of single phase in spinel ferrites was validated via X-ray diffraction technique. The advanced characterization tools like SEM, EDX, TEM, FTIR and UV-visible analytical and spectroscopic techniques were used to validates the surface morphology and the existence of only constituent elements and variable functional groups exists in the synthesized ferrites composites. BET analysis exhibit that the percentage of Sm\\u003csup\\u003e3+\\u003c/sup\\u003e NPs doping into the host ferrites over the pore size and surface area. Owing to the improved electrical conductivity due to fast charge carriers\\u0026rsquo; migration after the doping of rare earths NPs like Sm\\u003csup\\u003e3+\\u003c/sup\\u003e doped Co-Fe-O\\u003csub\\u003e4\\u003c/sub\\u003e ferrites composites shows superior electrochemical properties. The maximal specific capacitance of 850 F/g was shown by the CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) ferrite composite, which is far away excellent to pure CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e ferrite which is about 340 F/g. The synthesized ferrite composite shows that 98% of specific capacity retention even after the running of 5000 cycles of operation at 250 mV/s scan rate, which shows that good level of cycling performance. The electrode material fabricated by using CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e ferrite composites behave as positive electrode and at the same time activated nickel behave as negative electrode which render an energy density of 30.16 Wh/kg at a power density of 400 Wh/kg. The inclusion of rare earth (Sm\\u003csup\\u003e3+\\u003c/sup\\u003e) NPs into the Co-Fe-O\\u003csub\\u003e4\\u003c/sub\\u003e ferrite nanocomposites proposed that its major usages in the field of energy storage applications especially supercapacitors.\\u003c/p\\u003e\"},{\"header\":\"Declarations\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eData Availability:\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eData will be made available on request.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eCRediT authorship contribution statement:\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eSyed Khasim:\\u003c/strong\\u003e Methodology, Validation, Investigation and Writing the original draft of the manuscript. \\u003cstrong\\u003eApsar Pasha\\u003c/strong\\u003e: Supervision, Conceptualization, Writing-review and editing the manuscript. \\u003cstrong\\u003eB.N. Ramakrishna\\u003c/strong\\u003e: Editing the manuscript, English language usage, analysis of materials characterization and sensor results. \\u003cstrong\\u003ePrathibha.BS and Koushalya.PR\\u003c/strong\\u003e: Acquiring the characterization data and Software analysis.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eDeclaration of competing interest:\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\\u003c/p\\u003e\"},{\"header\":\"References\",\"content\":\"\\u003col\\u003e\\n\\u003cli\\u003eL.Liu, H.Zhao, Y.Lei, Review on nano architecture current collectors for pseudo capacitors, Small Methods 1800341 (2018) 1\\u0026ndash;25, https://doi.org/10.1002/ smtd.201800341.\\u003c/li\\u003e\\n\\u003cli\\u003eR.R. Palem, S. Ramesh, I. Rabani, G. Shimoga, C. Bathula, H.S. Kim, Y.S. Seo, H. S. Kim, S.H. Lee, Micro structurally assembled transition metal oxides with cellulose nanocrystals for high-performance supercapacitors, J. Energy Storage 50 (2022), 104712, https://doi.org/10.1016/j.est.2022.104712.\\u003c/li\\u003e\\n\\u003cli\\u003eX.Z.Xin-hui Xia, Jiang-ping Tu, Yong-qi Zhang, Yong-jin Mai, Xiu-li Wang, Chang[1]dong Gu, Freestanding Co\\u003csub\\u003e3\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e nanowire array for high performance supercapacitors, RSC Adv. 2 (2012) 1835\\u0026ndash;1841, https://doi.org/10.1039/ c1ra00771h.\\u003c/li\\u003e\\n\\u003cli\\u003eC. Bathula, I. Rabani, S. Ramesh, S.-H. Lee, R.R. Palem, A.T.A. Ahmed, H.S. Kim, Y.-S. Seo, H.-S. Kim, highly efficient solid-state synthesis of Co3O4 on multiwalled carbon nanotubes for supercapacitors, J. Alloys Compd. 887 (2021), 161307, https://doi.org/10.1016/j.jallcom.2021.161307\\u003c/li\\u003e\\n\\u003cli\\u003eR.R. Palem, I. Rabani, S. Ramesh, G. Shimoga, S.H. Lee, H.S. Kim, Y.S. Seo, H. S. Kim, C. 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Moholkar, Synthesis of NiO nanoparticles for supercapacitor application as an efficient electrode material, Vacuum 181 (2020), 109646, https://doi.org/ 10.1016/j.vacuum.2020.109646.\\u003c/li\\u003e\\n\\u003c/ol\\u003e\"},{\"header\":\"Tables\",\"content\":\"\\u003cp\\u003eTable.1 EDS analysis of CoFe\\u003csub\\u003e2-x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e ferrites composites (x=0.0, x=0.050, x=0.075 and x=0.1).\\u003c/p\\u003e\\n\\u003cdiv align=\\\"center\\\"\\u003e\\n \\u003ctable border=\\\"0\\\" cellspacing=\\\"0\\\" cellpadding=\\\"0\\\"\\u003e\\n \\u003ctbody\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"30.68893528183716%\\\" colspan=\\\"2\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eFe\\u003csup\\u003e3+\\u003c/sup\\u003e and Samarium \\u0026nbsp; Concentration (x)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"14.19624217118998%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eElements\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"27.55741127348643%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eComposition Theoretical values\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"27.55741127348643%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eComposition from EDS analysis\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"29.166666666666668%\\\" rowspan=\\\"3\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003cp\\u003eX=0.00\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"15.833333333333334%\\\" colspan=\\\"2\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eCo\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"27.5%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"27.5%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e1.0136\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"22.352941176470587%\\\" colspan=\\\"2\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eFe\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"38.8235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e2\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"38.8235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e1.9448\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"22.352941176470587%\\\" colspan=\\\"2\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eSm\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"38.8235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e0\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"38.8235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e0.0000\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"29.166666666666668%\\\" rowspan=\\\"3\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003cp\\u003eX=0.050\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"15.833333333333334%\\\" colspan=\\\"2\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eCo\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"27.5%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"27.5%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e1.0243\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"22.352941176470587%\\\" colspan=\\\"2\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eFe\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"38.8235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e1.95\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"38.8235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e1.8341\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"22.352941176470587%\\\" colspan=\\\"2\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eSm\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"38.8235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e0.050\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"38.8235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e0.0501\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"29.166666666666668%\\\" rowspan=\\\"3\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003cp\\u003eX=0.075\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"15.833333333333334%\\\" colspan=\\\"2\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eCo\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"27.5%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"27.5%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e1.0232\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"22.352941176470587%\\\" colspan=\\\"2\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eFe\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"38.8235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e1.925\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"38.8235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e1.8627\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"22.352941176470587%\\\" colspan=\\\"2\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eSm\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"38.8235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e0.075\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"38.8235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e0.0713\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"29.166666666666668%\\\" rowspan=\\\"3\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003cp\\u003eX=0.1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"15.833333333333334%\\\" colspan=\\\"2\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eCo\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"27.5%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"27.5%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e1.0232\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"22.352941176470587%\\\" colspan=\\\"2\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eFe\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"38.8235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e1.90\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"38.8235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e1.8736\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"22.352941176470587%\\\" colspan=\\\"2\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eSm\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"38.8235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e0.1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"38.8235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e0.1028\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003c/tbody\\u003e\\n \\u003c/table\\u003e\\n\\u003c/div\\u003e\\n\\u003cp\\u003eTable.2 Surface area, average pore diameter and pore volume for different electrode materials.\\u003c/p\\u003e\\n\\u003ctable border=\\\"0\\\" cellspacing=\\\"0\\\" cellpadding=\\\"0\\\" width=\\\"680\\\"\\u003e\\n \\u003ctbody\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"8.382352941176471%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eSl.No\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"19.41176470588235%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eElectrode material\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"20.88235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eSurface area (m\\u003csup\\u003e2\\u003c/sup\\u003e/g)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"29.11764705882353%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eAverage pore diameter (nm)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"22.205882352941178%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003ePore volume (cm\\u003csup\\u003e3\\u003c/sup\\u003e/g)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"8.382352941176471%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"19.41176470588235%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eX=0\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"20.88235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e080.323\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"29.11764705882353%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e08.56\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"22.205882352941178%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e0.28\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"8.382352941176471%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e2\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"19.41176470588235%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eX=0.050\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"20.88235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e123.712\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"29.11764705882353%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e16.67\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"22.205882352941178%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e0.34\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"8.382352941176471%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e3\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"19.41176470588235%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eX=0.075\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"20.88235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e181.344\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"29.11764705882353%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e31.89\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"22.205882352941178%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e0.65\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd width=\\\"8.382352941176471%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e4\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"19.41176470588235%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003eX=0.1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"20.88235294117647%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e208.267\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"29.11764705882353%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e40.03\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd width=\\\"22.205882352941178%\\\" valign=\\\"top\\\"\\u003e\\n \\u003cp\\u003e0.96\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003c/tbody\\u003e\\n\\u003c/table\\u003e\"}],\"fulltextSource\":\"\",\"fullText\":\"\",\"funders\":[],\"hasAdminPriorityOnWorkflow\":false,\"hasManuscriptDocX\":true,\"hasOptedInToPreprint\":true,\"hasPassedJournalQc\":\"\",\"hasAnyPriority\":false,\"hideJournal\":true,\"highlight\":\"\",\"institution\":\"\",\"isAcceptedByJournal\":false,\"isAuthorSuppliedPdf\":false,\"isDeskRejected\":\"\",\"isHiddenFromSearch\":false,\"isInQc\":false,\"isInWorkflow\":false,\"isPdf\":false,\"isPdfUpToDate\":true,\"isWithdrawnOrRetracted\":false,\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"researchsquare\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":true,\"externalIdentity\":\"\",\"sideBox\":\"\",\"snPcode\":\"\",\"submissionUrl\":\"/submission\",\"title\":\"Research Square\",\"twitterHandle\":\"researchsquare\",\"acdcEnabled\":true,\"dfaEnabled\":false,\"editorialSystem\":\"\",\"reportingPortfolio\":\"\",\"inReviewEnabled\":false,\"inReviewRevisionsEnabled\":true},\"keywords\":\"Rare earth (RE), Samarium NPs, Solution combustion method, Ferrite nanocomposite, Electrochemical analysis, Electrode materials and Supercapacitor\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-4177651/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-4177651/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"\\u003cp\\u003eHerein, we present the design and fabrication of samarium (Sm\\u003csup\\u003e3+\\u003c/sup\\u003e) doped cobalt-iron oxide ferrites nanocomposites for utilization as an efficient energy storage material. We have employed a simple, low cost and quick one step solution combustion method used to synthesize CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.0, 0.050, 0.075 and 0.1) ferrites composites. The synthesized CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e NPs undergo different analytical and spectroscopic characterizations methods like scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and ultraviolet visible (UV-visible) analytical and spectroscopic methods that used to confirm the morphological and structural properties of the synthesized NPs. The electrochemical properties synthesized ferrites composites were significantly improved after inclusion of rare earth (RE) metal such as samaniuim (Sm\\u003csup\\u003e3+\\u003c/sup\\u003e) nanoparticles (NPs) into the host cobalt-iron-oxide. It was notice that the creation of single phase in pure CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e ferrite remains unaltered by the mechanism of doping even in the ferrites composite. Nevertheless, doping of RE metal significantly influences over the morphological and structural properties, further more enhancement in the electrochemical performance of samarium doped CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e ferrite composite. The highest specific capacity about 850 F/g was achieved for CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) composite electrode material, which shows more superior in compare to pure CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0) which is about 340 F/g. However, CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e (x\\u0026thinsp;=\\u0026thinsp;0.1) composite shows a superior capacitance retention of the order of 98% even after 5000 cycles of operation at a scan rate of 250 mV/s. The electrode material fabricated by using CoFe\\u003csub\\u003e2\\u0026thinsp;\\u0026minus;\\u0026thinsp;x\\u003c/sub\\u003eSm\\u003csub\\u003ex\\u003c/sub\\u003eO\\u003csub\\u003e4\\u003c/sub\\u003e ferrite composites behave as positive electrode and at the same time activated nickel behave as negative electrode which is render an energy density of 30.16 Wh/kg at a power density of 400 Wh/kg. The results obtained in presented studies offer a hopeful way for the fabrication high-performance electrode material for supercapacitor which is more suitable for light weight electronic devices, electric vehicles, and forthcoming generation supercapacitor applications.\\u003c/p\\u003e\",\"manuscriptTitle\":\"Facile synthesis of Samarium (Sm 3+ ) doped Cobalt-iron oxide nano ferrite as an advanced electrode material for supercapacitor applications\",\"msid\":\"\",\"msnumber\":\"\",\"nonDraftVersions\":[{\"code\":1,\"date\":\"2024-04-02 17:51:47\",\"doi\":\"10.21203/rs.3.rs-4177651/v1\",\"editorialEvents\":[{\"type\":\"communityComments\",\"content\":0}],\"status\":\"published\",\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"researchsquare\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":true,\"externalIdentity\":\"\",\"sideBox\":\"\",\"snPcode\":\"\",\"submissionUrl\":\"/submission\",\"title\":\"Research Square\",\"twitterHandle\":\"researchsquare\",\"acdcEnabled\":true,\"dfaEnabled\":false,\"editorialSystem\":\"\",\"reportingPortfolio\":\"\",\"inReviewEnabled\":false,\"inReviewRevisionsEnabled\":true}}],\"origin\":\"\",\"ownerIdentity\":\"2bfc76c5-ca63-4e13-bd87-7a94f3893e62\",\"owner\":[],\"postedDate\":\"April 2nd, 2024\",\"published\":true,\"recentEditorialEvents\":[],\"rejectedJournal\":[],\"revision\":\"\",\"amendment\":\"\",\"status\":\"posted\",\"subjectAreas\":[],\"tags\":[],\"updatedAt\":\"2024-04-09T14:23:44+00:00\",\"versionOfRecord\":[],\"versionCreatedAt\":\"2024-04-02 17:51:47\",\"video\":\"\",\"vorDoi\":\"\",\"vorDoiUrl\":\"\",\"workflowStages\":[]},\"version\":\"v1\",\"identity\":\"rs-4177651\",\"journalConfig\":\"researchsquare\"},\"__N_SSP\":true},\"page\":\"/article/[identity]/[[...version]]\",\"query\":{\"redirect\":\"/article/rs-4177651\",\"identity\":\"rs-4177651\",\"version\":[\"v1\"]},\"buildId\":\"qtupq5eGEP_6zYnWcrvyt\",\"isFallback\":false,\"isExperimentalCompile\":false,\"dynamicIds\":[84888],\"gssp\":true,\"scriptLoader\":[]}","source_license":"CC-BY-4.0","license_restricted":false}