Faculty Publications
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Item Activated carbon- supported Vanado-nickelate (IV) based hybrid materials for energy application(Elsevier Ltd, 2021) Maity, S.; BM, N.; Kella, T.; Shee, D.; Das, P.P.; Mal, S.S.The rapid development of supercapacitor (SC) technology leads to increased demand for nanofabrication of novel and effective electroactive hybrid materials for next-generation energy storage devices. Herein, nickel tetradecavanadate, K2H5[NiV14O40](NiV14), is doped into porous activated carbon (AC), for the first time, in different wt.% in order to investigate the homogeneous loading of the inorganic metal-oxide component on the AC matrix. The resulting complex, AC-NiV14, is found to have possessed an enhanced electrochemical characteristic (for both symmetric and asymmetric SC cell), which operates at a significantly higher potential of 1.2 V. The combination of the double-layer capacitance (EDLC) and the redox-active polyoxometalate cluster leads to an intrinsic increase in specific capacitance (capacity) (from 45.3 Fg?1 (54.4 Cg?1) for AC to 316 Fg?1 (379.2 Cg?1) for 15 wt.% AC-NiV14 at a current density of 1 Ag?1). It was also observed that there is an increase of 20% in the operating voltage compared to conventional AC supercapacitors with acidic aqueous electrolytes. Firstly, symmetric supercapacitor's electrochemical performances of various wt.% of NiV14 composition were studied in acidic aqueous electrolyte (0.5 M H2SO4) solution. We observed that the 15 wt.% of AC-NiV14 hybrid electrode showed remarkable specific energy value (~63.2 Wh kg?1) compared with pristine AC and NiV14 electrodes, separately. Besides, the asymmetric layout (AC//AC-NiV14) increased the potential window up to 1.5 V and enhanced the specific energy and power values (90.1 Whkg?1 and 2400 Wkg?1, respectively), with 98% coulombic efficiency. Meanwhile, the AC-NiV14//NiV14 asymmetric cell possesses a specific capacitance (capacity) of 375 Fg?1 (450 Cg?1) with a maximum power of 3140 Wkg?1 at the high current density of 2 Ag?1. © 2021 Elsevier LtdItem Organic cation linkers polyoxomolybdate-polypyrrole nanocomposite-based supercapacitors(Springer Science and Business Media Deutschland GmbH, 2021) Muhammed Anees, P.K.; Anandan Vannathan, A.; Kella, T.; Shee, D.; Mal, S.A few new hybrid electrode materials have been synthesized and immobilized for the next-generation energy storage device. The hybrid electrodes PVMo11-TBA, PVMo11-BTA, PVMo11-TBP, PVMo11-TBA-PPy, PVMo11-BTA-PPy, and PVMo11-TBP-PPy were well characterized by NMR, XRD, FTIR, FESEM, BET, and tested for electrochemical performance. Among these hybrid electrode materials, the PVMo11-TBA-PPy electrode shows a high specific capacitance of 144.37 F/g at a 1A/g current density and incredible power and energy density of 1100.16 W/kg and 15.28 Wh/kg, respectively. The high electrode’s capacitance was due to the synergistic effect between the PPy and TBA-PVMo11 and high ionic diffusion compared with other synthesized electrodes. It also exhibited high cycle stability of 72.78% after 4500 cycles at 1 M H2SO4 electrolyte. The EIS offers a lower ESR value of 0.72 ohms for the PVMo11-TBA-PPy than PVMo11-TBA, indicating the rapid charge/discharge rate. On the other hand, the PVMo11-BTA-PPy and PVMo11-TBP-PPy electrodes showed lower capacitance values of 26.98 and 19.53. F/g at 0.4 and 1 A/g current density, respectively. Lowering the capacitance could be the prevention of the interaction of organic cations with the counter polyanion. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.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 Polyoxovanadate-Activated Carbon-Based Hybrid Materials for High-Performance Electrochemical Capacitors(Institute of Physics, 2022) Anandan Vannathan, A.; Chandewar, P.R.; Shee, D.; Mal, S.S.Two different polyoxovanadates derivatives, K5MnIVV11O32.10 H2O (MnV11) and K7MnIVV13O38.18 H2O (MnV13), have been studied to evaluate their electrochemical performance. These polyoxovanadates were deposited on activated carbon (AC) to prepare AC-MnV11 and AC-MnV13 composites. The electrochemical performance of the AC-MnV11 electrode exhibits the remarkable specific capacitance of 479.73 F g-1 at a current density of 0.6 A g-1, along with incredible specific power and energy of 960 W kg-1. Likewise, the AC-MnV13 exhibits a specific capacitance of 357.33 F g-1 at the current density of 0.6 A g-1 with a specific energy of 71.46 Wh kg-1. Interestingly, the AC-MnV11 could light up the red and yellow color LED bulbs for a duration of 80 and 60 s, respectively, indicating a considerable specific power of the material. The AC-MnV13 electrode shows significantly less lighting up during the 65 and 30 s period with red and yellow LED bulbs. © 2022 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.Item Phosphomolybdic acid embedded into biomass-derived biochar carbon electrode for supercapacitor applications(Elsevier B.V., 2023) J.e, M.; Chandewar, P.R.; Shee, D.; Mal, S.S.In high-performance, clean, safe, and cost-effective ways, supercapacitors are among the most promising ways to store and release nonfossil energy. In recent years, renewable biomass-derived activated carbon has been explored as a potential option for electrode material. It restricts their specific capacitance despite being environment-friendly and possessing intrinsic mechanical strength. In order to overcome this limitation and preserve all other properties, we are infusing polyoxometalate into the activated carbon; this increases specific capacitance with its fast reversible redox behaviour and preserves the carbon's characteristics. Beside suffusing phosphomolybdic acid (PMA) into biomass waste material, such as orange peel-derived activated carbon (OPAC), a new hybrid material (OPAC-PMA) was developed. The nanohybrid design was revealed by structural and morphological research, which showed high interfacial contact, allowing polyanions to redox rapidly. The novel hybrid electrode material (OPAC-PMA) has a capacitance value of 66% higher than the bare OPAC electrode. A further study showed that OPAC-PMA composite showed 88.23% cycle stability in 0.5 M H2SO4 electrolyte at 6 A g−1 for 4000 cycles. © 2023 Elsevier B.V.Item Waste dry cell derived photo-reduced graphene oxide and polyoxometalate composite for solid-state supercapacitor applications(Royal Society of Chemistry, 2023) Maity, S.; Biradar, B.R.; Srivastava, S.; Chandewar, P.R.; Shee, D.; Das, P.; Mal, S.S.In the modern era, realizing highly efficient supercapacitors (SCs) derived through green routes is paramount to reducing environmental impact. This study demonstrates ways to recycle and reuse used waste dry cell anodes to synthesize nanohybrid electrodes for SCs. Instead of contributing to landfill and the emission of toxic gas to the environment, dry cells are collected and converted into a resource for improved SC cells. The high performance of the electrode was achieved by exploiting battery-type polyoxometalate (POM) clusters infused on a reduced graphene oxide (rGO) surface. Polyoxometalate (K5[α-SiMo2VW9O40]) assisted in the precise bottom-up reduction of graphene oxide (GO) under UV irradiation at room temperature to produce vanadosilicate embedded photo-reduced graphene oxide (prGO-Mo2VW9O40). Additionally, a chemical reduction route for GO (crGO) was trialed to relate to the prGO, followed by the integration of a faradaic monolayer (crGO-Mo2VW9O40). Both composite frameworks exhibit unique hierarchical heterostructures that offer synergic effects between the dual components. As a result, the hybrid material's ion transport kinetics and electrical conductivity enhance the critical electrochemical process at the electrode's interface. The simple co-participation method delivers a remarkable specific capacity (capacitance) of 405 mA h g−1 (1622 F g−1) and 117 mA h g−1 (470 F g−1) for prGO-Mo2VW9O40 and crGO-Mo2VW9O40 nanocomposites alongside high capacitance retentions of 94.5% and 82%, respectively, at a current density of 0.3 A g−1. Furthermore, the asymmetric electrochromic supercapacitor crGO//crGO-Mo2VW9O40 was designed, manifesting a broad operating potential (1.2 V). Finally, the asymmetric electrode material resulted in an enhanced specific capacity, energy, and power of 276.8 C g−1, 46.16 W h kg−1, and 1195 W kg−1, respectively, at a current density of 0.5 A g−1. The electrode materials were tested in the operating of a DC motor. © 2023 The Royal Society of Chemistry.Item High-performance hybrid supercapacitor-immobilized Wells-Dawson polyoxometalates on activated carbon electrodes(Royal Society of Chemistry, 2023) Madhusree, J.E.; Chandewar, P.R.; Shee, D.; Mal, S.S.The nanofabrication of electroactive hybrid materials for next-generation energy storage devices is becoming increasingly significant as supercapacitor (SC) technology develops rapidly. The present study utilizes activated carbon (AC) templates reinforced with Wells-Dawson polyoxotungstates (POMs) to produce nanohybrid electrodes for high-performance supercapacitors. This study analyzes Wells-Dawson polyoxotungstates (P2W18) for the first time integrated with AC, and its structural and electrochemical performances are discussed. First, the electrochemical performances of symmetric supercapacitors were characterized in an acidic aqueous electrolyte (0.5 M H2SO4). It was observed that a supercapacitor cell containing the 5 wt% AC-P2W18 hybrid symmetric displayed a noteworthy specific capacitance of 289 F g−1 and a remarkable energy density of 40 W h kg−1. Moreover, 5% AC-P2W18 symmetric supercapacitor cells showed 89% cyclic stability over 4000 cycles. Three LED lights were charged onto the electrode. The LEDs continued to illuminate continuously for red until 160 seconds, yellow until 20 seconds, and blue until 10 seconds after removing the electrode from the electrochemical workstation, demonstrating the device's power and energy density. © 2023 The Royal Society of Chemistry.