Faculty Publications
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Item In situ vanadophosphomolybdate impregnated into conducting polypyrrole for supercapacitor(Elsevier Ltd, 2020) Anandan Vannathan, A.A.; Maity, S.; Kella, T.; Shee, D.; Das, P.P.; Mal, S.S.The fast modernization and advancement in lifestyle increase the consumption of power daily due to all innovative technologies, e.g., hybrid vehicles, solar cells, smart power grid, communication devices, artificial hearts, etc. Conducting organic polymer-based energy storage devices had attracted much attention due to the conductive nature for a long time. However, its application has been restricted because of swelling and shrinking capability during the charge and discharge cycle. The combination of redox-active inorganic metal oxides, such as polyoxometalates (multi-metal oxide cluster) with conduction polymers, could enhance the material's stability due to its fast multi-electron redox property. Here, we report the two polypyrroles combined vanadophosphomolybdates, namely PPy-H4[PVMo11O40] and PPy-H5[PV2Mo10O40] nanohybrid electrode materials. The PPy-H5[PV2Mo10O40] electrode material behaves as pseudocapacitance and can deliver an excellent capacitance of 561.1 F/g in 0.1 M H2SO4 electrolyte solution at a 0.2 A/g current density, indicating capacitive composite material. The electrochemical impedance spectroscopy (EIS) reveals that PPy-H5[PV2Mo10O40] is more capacitive than PPy-H4[PVMo11O40] and PPy with equivalent series resistance (ESR) of 5.74 ?. The cell capacitance of PPy-H5[PV2Mo10O40] and PPy-H4[PVMo11O40] are found to be 5.38 and 9.15 mF, stipulating in small SC cell application. Likewise, the PPy-H5[PV2Mo10O40] nanohybrid electrode shows better responsive behavior with a relaxation time of 0.16 ms. Furthermore, the PPy-H5[PV2Mo10O40] electrode exhibits outstanding cycle stability, retaining ~95% of its capacitance after 4500 cycles as compare to PPy-H4[PVMo11O40] (~91%) electrode. © 2020Item 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 Asymmetric polyoxometalate-polypyrrole composite electrode material for electrochemical energy storage supercapacitors(Elsevier B.V., 2022) Anandan Vannathan, A.; Chandewar, P.R.; Shee, D.; Mal, S.Nowadays, metal-oxides impregnated conducting polymers as electrode materials are attracted much attention due to their higher stability. Here, the metal-oxide cluster, polyoxometalate (K5H2[PV4W8O40]·11H2O, PV4W8), was introduced into the polypyrrole (PPy) matrix to overcome the polymers stability issues, and thus, the resulting novel PV4W8/PPy (symmetric) composite electrode has been reported. XPS confirmed the presence of all atoms on the polymer backbone with respective oxidation states. Nevertheless, doping of PV4W8 on the conductive PPy matrix's surface can affectively improve the ion's transfer. Finally, the asymmetric PV4W8-PPy/PPy composite exhibits a prodigious specific capacitance of 291 F g−1, larger than the PPy (90.01 F g−1) and PV4W8 (39.03 F g−1) at 0.4 A g−1 current density. The PV4W8-PPy/PPy (asymmetric) electrode showed excellent cycle stability. However, a symmetric supercapacitor device based on PV4W8/PPy composite possesses a specific capacitance of 195.27 F g−1 and an energy density of 8.94 Wh kg−1 at the same current density as PV4W8-PPy/PPy (asymmetric) electrode with remarkable cycle stability. © 2021 Elsevier B.V.Item Imidazolium cation linkers of polyoxomolybdate-polypyrrole nanocomposite electrode-based energy storage supercapacitors(Elsevier Ltd, 2022) Muhammed Anees, P.K.; Anandan Vannathan, A.A.; Abhijith, M.B.; Kella, T.; Shee, D.; Mal, S.S.The electrochemical properties of a new hybrid electrode, liquid-polyoxometalate-polypyrrole (BMIM-PVMo11-PPy) have been studied. The H4[PVMo11O40] (PVMo11) was combined with 1-Butyl-3-methyl-imidazolium (BMIM) ionic liquid and then doped on the polypyrrole (PPy) surface. In order to investigate the interaction between the BMIM, PVMo11, and PPy compound was characterized using various analytical techniques, such as Infrared spectroscopy, thermal stability analysis, powder X-ray diffraction, multinuclear NMR (1H and 13C), FESEM, EDX, and surface adsorption studies. The electrochemical performance of the BMIM-PVMo11-PPy composite material has been tested in an aqueous 0.25 M H2SO4 electrolytic solution. The BMIM-PVMo11-PPy composite exhibits the highest specific capacitance of 527.39 F g−1 at a current density of 1 A g−1, along with remarkable specific energy and power of 51.07 Wh kg−1 and 1078.96 W kg−1, respectively. The BMIM-PVMo11-PPy composite was observed to light up red and blue color LED bulbs for 66 and 16 s, respectively, with 84 mg of sample coated on carbon cloth, suggesting an incredible specific power of that material. © 2021 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 areal capacitance polyoxotungstate-reduced graphene oxide-based supercapacitors(Elsevier B.V., 2023) Biradar, B.R.; Maity, S.; Chandewar, P.R.; Shee, D.; Das, P.P.; Mal, S.S.The modern lifestyle has driven the advent of high-power electronic gadgets to need high-efficiency energy storage devices. Towards that goal, reduced graphene oxide (rGO) mediated polyoxometalates (POMs) based electrode materials are increasingly showing promising performance for building efficient energy storage devices primarily due to their redox properties. In this report, the silicotungstate [K5[SiVW11O40]. nH2O (SiVW11) embedded rGO nanocomposites as electrode materials in supercapacitor applications were synthesized via chemical and hydrothermal methods. The synthesized nanocomposites were characterized by various techniques, such as Fourier-Transform-Infrared (FTIR) Spectroscopy, Powder X-ray Diffraction (XRD) and Energy Dispersive X-ray Spectroscopy (EDS), Thermogravimetric Analysis (TGA), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) measurement. The nanocomposite's electrochemical properties were examined by adopting a two-electrode setup with cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) in a 0.5 M H2SO4 electrolyte medium. The hydrothermally reduced graphene oxide (HrGO) nanocomposite exhibited a noticeable surge in areal capacitance of 377.4 mF/cm2 at a current density of 1.5 mA/cm2. The resulting composite had 52.4 µWh/cm2 and 1500 µW/cm2 as energy and power density, respectively at 1.5 mA/cm2 current density. In addition, the capacitance retention is over 81% after 5000 cycles at a current density of 9 mA/cm2. The highest specific power of 5000 µW/cm2 was obtained at 5 mA/cm2 current density. On the other hand, chemically reduced graphene (CrGO) nanocomposite showed an areal capacitance of 277.2 mF/cm2 at the same current density. As a result, the SiVW11 clusters coupled with the rGO increase the areal capacitance of nanocomposites with exceptional electrical and mechanical stability. From an application standpoint, both composites were employed successfully for running a DC motor in a series cell connection. © 2023 Elsevier B.V.Item High-performance electrochemical supercapacitors based on polyoxometalate integrated into polyaniline and activated carbon nanohybrid(Springer Science and Business Media Deutschland GmbH, 2023) Anandan Vannathan, A.A.; Kella, T.; Shee, D.; Mal, S.S.Polyaniline (PANI) and carbonaceous materials and metallic compounds have played a significant role in energy storage and conversion devices. PANI has demonstrated tremendous potential in the supercapacitor industry due to its high specific capacitance, high flexibility, and economical price. The CPs damage the hierarchical structure during the charging and discharging process and start swelling. Thus, incorporating polyoxometalates (POMs) into the conducting polymer matrix increases the stability of the electrode material. Here, we have demonstrated a comparative study of two newly synthesized composite materials consisting of K5H2[PV4W8O40] ·11H2O, (PV4W8) POM incorporated into two different supports, such as pseudocapacitive polyaniline (PANI) and EDLC activated carbon (AC) matrix. It was observed that the PANI-PV4W8 composite exhibited excellent capacitance nature at 0.5 M H2SO4 electrolyte solution than AC-PV4W8. The PANI-PV4W8 composite demonstrated the specific capacitance of 584 F g−1 at 0.8 A g−1. The composite also exhibited energy and power density of 81Wh kg−1 and 1598 W kg−1, respectively. Besides, the composite shows 93.13% capacity retention after 4500 cycles by cyclic voltammetry measurement at a 500 mV s−1 scan rate. Furthermore, the AC-PV4W8 showed a specific capacitance of 62 F g−1 at the current density of 0.6 A g−1. Interestingly, The PANI-PV4W8 composite could glow up the red and yellow LED bulb for more than a minute, suggesting a promising electrode material for practical supercapacitor purposes. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.Item Synergistic Enhancement of Supercapacitor Performance: Vanadium-Substituted Phosphotungstic and Molybdic Acid Combined with Polypyrrole Using Pyridinium and Ammonium Ionic Containing Organic Cation Linkers with Improved Conductivity(John Wiley and Sons Inc, 2024) Puniyanikkottil, M.A.; Chandewar, P.R.; Shee, D.; Mal, S.S.High-performance energy-storage devices have emerged as a favored choice owing to their remarkable efficiency, sustainability, and environmental friendliness. Nowadays, polyoxometalate (POM)-based supercapacitor (SC) electrode materials have gained much attention. Herein, a few new POMs and ionic liquid (IL) composites incorporated into conducting polymer as electrode materials for SC applications are reported. The H6[PV3Mo9O40]⋅34H2O (PV3Mo9) and H6[PV3W9O40].34H2O (PV3W9) POMs are treated with tetrabutylammonium chloride and 1-butyl-4-methyl pyridinium chloride (BMP) and finally combined with polypyrrole (PPy) for the SC studies. An extensive array of analytical techniques is employed to delve into the interplay between the constituents within the composite materials, such as Fourier transform infrared spectroscopy, powder X-ray diffraction, thermogravimetric analysis, nuclear magnetic resonance (1H and 13C), Field-emission scanning electron microscopy, energy-dispersive X-ray stpectroscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller surface area. The combined application of these techniques enables us to understand the interaction dynamics within composite materials comprehensively. POM–ILs combination improves the solubility issues of POMs, and doping of PPy enhances the electrochemical performances of the materials. The PV3W9–BMP–PPy symmetric SC cell shows a specific capacitance of 294.79 F g−1 and an energy density of 28.89 Wh kg−1 at 1 A g−1 current density in 0.25 M H2SO4 medium followed by an excellent cycle life of 78.6% after 10,000 galvanostatic charge–discharge cycles. The fabricated SC device is performed to light up the bulbs of red, yellow, and green light emitting diodes for 50, 30, and 28 s, respectively. © 2024 Wiley-VCH GmbH.