Faculty Publications
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Item Improved electrochemical performance of graphene oxide supported vanadomanganate (IV) nanohybrid electrode material for supercapacitors(Elsevier Ltd, 2020) Kumari, S.; Maity, S.; Anandan Vannathan, A.A.; Shee, D.; Das, P.P.; Mal, S.S.Graphene oxide (GO)-supported polyoxometalates (POMs) have been considered as promising electrode materials for energy storage applications due to their ability to undergo fast and reversible redox reactions. Herein, vanadomanganate-GO composites (K7MnIVV13O38.18H2O-GO with 2:1 and 4:1 ratio) were investigated for use as potential electrode materials in supercapacitors (SCs). The K7MnIVV13O38.18H2O (MnV13) was synthesized and anchored on GO through electron transfer interaction and electrostatic interaction to make the composite electrodes for the present study. All synthesized electrode materials were fully characterized by various techniques, e.g., Fourier Transform Infrared (FTIR) Spectroscopy, Powder X-ray Diffraction (XRD), Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDS) and High Resolution-Transmission Electron Microscopy (HR-TEM). The electrochemical properties of MnV13/GO composites with different MnV13/GO ratios were investigated by two-electrode cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) in different electrolytes. The MnV13/GO composite of ratio 2:1 in 1 M LiCl electrolyte and that of ratio 4:1 in 1 M Na2SO4 electrolyte showed significant specific capacitance values of 269.15 F/g and 387.02 F/g, respectively and energy density of 37.38 Wh/kg and 53.75 Wh/kg, respectively for a scan rate of 5 mV/s. Interestingly, the 1:1 (MnV13/GO) composite in 1 M Na2SO4 and 1 M LiCl electrolytes showed very low specific capacitance values as the deposition of MnV13 on GO was not sufficient, as indicated by FTIR and SEM. Thus, it is evident that the specific capacitance value of these composite materials depends on the amount of MnV13 deposited on GO and these composite materials exhibit the potential to improve the performance of GO-based SCs. © 2019Item Electrochemical performance of activated carbon-supported vanadomolybdates electrodes for energy conversion(Elsevier Ltd, 2021) Maity, S.; Anandan Vannathan, A.; Kella, T.; Shee, D.; Das, P.P.; Mal, S.Reinforcing polyoxomolybdates (POMs) into the activated carbon (AC) template engenders a nanohybrid electrode material for high-performance supercapacitor applications. Herein, a first-time novel integration of two polyoxometalates ([PVMo11O40]4-, [PV2Mo10O40]5-) with AC has been demonstrated, and their structural and electrochemical performances were analyzed. AC-VMo11 composite displayed an enhanced capacitance of 450 Fg-1 with an improved energy density of 59.7 Whkg-1. Furthermore, the symmetric supercapacitor cell for AC-VMo11 and AC-V2Mo10 showed high cell capacitances of 38.8 and 20.01 mF, respectively, alongside 99.99% capacitance retention of over 5000 cycles. In addition, the influence of ionic liquid as an electrolyte on AC-V2Mo10 based supercapacitor cell was investigated in tetrabutylammonium bromide (TBAB) electrolyte solution. © 2021 Elsevier Ltd and Techna Group S.r.l.Item Polyoxomolybdate-Polypyrrole-Graphene Oxide Nanohybrid Electrode for High-Power Symmetric Supercapacitors(American Chemical Society, 2021) Maity, S.; Je, M.; Biradar, B.R.; Chandewar, P.R.; Shee, D.; Das, P.P.; Mal, S.Supercapacitors have emerged as one of the most promising candidates for high-performance, safe, clean, and economical routes to store and release of nonfossil energy. Designing hybrid materials by integrating double-layer and pseudocapacitive materials is crucial to achieving high-power and high-energy storage devices simultaneously. Herein, we synthesized a polyoxomolybdate-polypyrrole-graphene oxide nanohybrid via a one-pot reaction. The inclusion of polypyrrole enables a uniform distribution of the polyoxomolybdate clusters; it also confines the restacking of graphene oxide nanosheets. The structural and morphological analysis to unveil the nanohybrid architecture implies excellent interfacial contact, enabling fast redox reaction of polyanions, and a quick transfer of charge to the interfaces. Electrochemical characteristics tested under a two-electrode system exhibit the highest capacitance of 354 F g-1 with significantly high specific energy and power of 49.16 Wh kg-1 and 999.86 W kg-1, respectively. In addition, the cell possesses a high-rate capability and long cycle life by maintaining 96% of its capacitance over 5000 sweeping cycles. The highest specific power of ?10 »000 W kg-1 was computed with Coulombic efficiency of 92.30% at 5 A g-1 current density. Electrochemical impedance spectroscopy additionally reveals enhanced redox charge transfer due to double hybridization. Furthermore, it also demonstrates the impedance and capacitive behavior of supercapacitor cells over a definite frequency regime. ©Item Decavanadate-graphene oxide nanocomposite as an electrode material for electrochemical capacitor(Taylor and Francis Ltd., 2022) Maity, S.; Das, P.P.; Mal, S.We have synthesized new electrode material for the supercapacitor application. Polyoxovanadates (POVs) have been used for energy storage electrode materials due to their fast multi-electron redox properties. The formation of SDV/GO composites was confirmed using various analytical methods, e.g., Fourier transforms infrared spectroscopy (FTIR) and powder X-ray diffraction (XRD), followed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The composite electrode’s electrochemical behavior was studied using a neutral 1 M sodium sulphate (Na2SO4) solution in three-electrode cyclic voltammetry (CV) system. The SDV/GO composite electrode showed a specific capacitance of 306 F/g for a scan rate of 5 mV/s and a corresponding energy density of 42.4 Wh/Kg. Galvanostatic charge/discharge exhibits a specific capacitance of 310 F/g with energy densities of 43.08 Wh/kg. Electrochemical impedance spectroscopy (EIS), which was used to investigate interface property, yielded a considerably higher power density of 172.41 KW/kg with an equivalent series resistance of 5 ?. © 2021 Informa UK Limited, trading as Taylor & Francis Group.Item Vanadomanganate as a synergistic component in high-performance symmetric supercapacitor(Elsevier Ltd, 2022) Maity, S.; Anandan Vannathan, A.A.; Chandewar, P.R.; Shee, D.; Das, P.P.; Mal, S.S.Supercapacitor devices fabricated from capacitive and battery-type hybrid electrodes have been projected as a promising energy storage system because of their ability to produce high specific power and energy simultaneously. In this work, we have demonstrated a facile method of impregnation of faradaic type manganese (III) polyoxovanadate, [MnV14O40]−6 on the high surface area substrate of activated carbon (AC) as well as graphene oxide (GO). Materials and electrochemical characterizations data confirm the successful incorporation of capacitive and faradaic type manganese (III) polyoxovanadate into the nanohybrid electrode material. Furthermore, the synergic effect between the carbonaceous nanostructures (AC/GO) and redox-active oxometalate (MnV14) provides a better pathway for ion transport to the interface resulting in enhancement of the conductivity, diffusion ability of the nanohybrid. Moreover, the battery-type MnV14 clusters disperse in the micro/mesopores of AC, whereas the oxygen-containing functional groups in GO act as active sites for anchoring of MnV14 clusters. Thus, the surface modification with MnV14 clusters enhances the specific capacitance of nanohybrid with remarkable electrical and mechanical stability. The AC/MnV14 nanohybrid exhibits an enhanced specific capacitance of 547 F g−1 with specific energy and power of 76 Wh kg−1 and 1600 W kg−1, respectively, at 0.8 A g−1 current density. Additionally, GO/MnV14 shows a specific capacitance of 330 F g−1 with improved specific energy and power of 30 Wh kg−1 and 1276 W kg−1, respectively, at the same current density. Moreover, both the nanohybrids possess excellent cycle stability by retaining 92% (AC/MnV14) and 90.6% (GO/MnV14) of initial capacitance even after 5000 sweeping cycles. © 2021 Elsevier B.V.Item Fabrication of supercapacitor electrode material using carbon derived from waste printer cartridge(Springer Science and Business Media Deutschland GmbH, 2024) Biradar, B.R.; Maity, S.; Chandewar, P.R.; Shee, D.; Das, P.P.; Mal, S.S.Transforming recyclable materials into a suitable product is an important area of research nowadays. This report demonstrates that carbon material derived from waste printer cartridges can be exploited to fabricate electrochemical cells—particularly supercapacitors (SCs). SCs are electrochemical energy storage devices currently attracting much attention in the research community due to their salient features, such as cost-effectiveness, extended cycle stability, and durability. Here, we report the results of thoroughly examining the effects of acidic, basic, and neutral aqueous electrolytes on printer waste carbon electrode material in SC efficiency. In our work, the waste carbon collected from used printer cartridges shows a specific capacitance of 178.4 F/g with energy and power density of 24.77 Wh/kg and 999.68 W/kg, respectively, at 0.5 A/g current density in acidic (1 M H2SO4) electrolyte medium. Moreover, it exhibited very promising capacitance of 135.04 F/g and 87.04 F/g in basic (1 M LiOH) and neutral (1 M NaCl) electrolyte medium, respectively, at 0.8 A/g current density with considerably better cycle stability. In an acidic medium, printer waste carbon drives a DC motor for 1 min with a three-cell series arrangement. The properties of that waste carbon (extracted from the cartridges) are similar to high-rate activated carbon available commercially. Graphical Abstract: (Figure presented.). © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.Item Optimization of Quantum Capacitance of Functionalized VS2 Monolayer Electrodes to Shrink Hybrid Supercapacitors for On-Chip Energy Sources(American Chemical Society, 2025) Yadav, A.K.; Thiyyakkandy, J.; Singh, R.; Das, P.P.; Ajith, K.M.; Pandey, S.K.Quantum capacitance (CQ) of the electrodes plays an important role in enhancing the performance of supercapacitors by directly affecting the overall capacitance. In this study, several approaches including doping, creating vacancy, and adsorption have been used to enhance the CQ of the vanadium disulfide (VS2) electrode using density functional theory calculation. The undoped VS2 monolayer shows a maximum CQ value of 20.19 ?F/cm2. After creating V-vacancy (Vv) in the VS2 monolayer lattice, the CQ value increased to 35.61 ?F/cm2, which is the highest among all doped and defective VS2 lattices at room temperature. When we use VS2 electrodes for supercapacitors, generally ion adsorption occurs at the electrode surface, showing the necessity to investigate the adsorption of alkali/alkaline atoms (Li, Na, K, and Mg) at the VS2 surface to know the change in different properties of the electrode. It is found that generally CQ reduces due to the adsorption of alkali/alkaline atoms at the surface, but the K-adsorption at S-vacancy (Vs) VS2 demonstrated the increment of CQ value from 21.75 to 35.32 ?F/cm2 at room temperature. Additionally, the variation of the adsorption distance of the K atom at the Vs-VS2 surface revealed an optimum distance of value 3.5 Å, indicating that the K atom (radius = 2.43 Å) stabilizes just above the VS2 surface. Moreover, augmentation in CQ was seen with a decrease in temperature and attained a value of 49.96 ?F/cm2 at 100 K. The calculated CQ and open-circuit voltage (OCV) duly confirmed that the K-adsorbed Vs-VS2 is a potential candidate for the anode of hybrid supercapacitors as it has a maximum CQ value at the positive side of the electrochemical potential and an average OCV value of +0.615 V. This study reveals that the CQ of the VS2 electrode can be increased to minimize the size of high-performance hybrid supercapacitors for its application as an on-chip energy source. © 2025 American Chemical Society.Item Carbon Nanotube-Supported Vanadium Substituted Phospho-Molybdate Nanohybrid for Supercapacitor Applications(John Wiley and Sons Inc, 2025) Biradar, B.R.; Swetha, M.T.; Thathron, N.; Puniyanikkottil, M.A.; Hanchate, A.; Das, P.P.; Mal, S.S.Owing to the depletion of conventional energy sources, our civilization is slowly transitioning to renewables. Therefore, designing effective energy storage systems is one of the most pressing technical demands. The quest for improved energy and power densities in energy storage devices, particularly those with long cycle life, has pushed the investigation of novel materials intended to build effective supercapacitors. In this work, nanohybrid materials are synthesized using a hydrothermal technique by mixing carbon nanotubes and a polyoxometalate cluster, H4[PVMo11O40].xH2O. Henceforth, this complex is acronymed as CNT-PVMo11. Further, electrochemical analysis of CNT-PVMo11 nanohybrid is carried out to examine various characteristics of the supercapacitor cell made with this nanohybrid. The cyclic voltammetry confirms the diffusive-dominant charge-storage process, quantifying a 72.83% diffusion mechanism at a scan rate of 1 mV s?1. The galvanostatic charge–discharge analysis of CNT-PVMo11 nanohybrid material showed a specific capacitance of 229.35 F g?1 with energy and power densities of 31.85 Wh kg?1 and 2000 W kg?1, respectively, at 1 A g?1 current density. The electrode material also shows 90% capacitance retention even after 6000 cycles at 8 A g?1 current density, indicating the material's remarkable stability. The high specific capacitance, excellent energy density, and impressive cycling stability of the hybrid material make it a promising candidate for next-generation supercapacitor electrodes. © 2025 Wiley-VCH GmbH.