Faculty Publications
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Item 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 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 Investigations into the supercapacitor activity of bisphosphonate-polyoxovanadate compounds(Academic Press Inc., 2021) Anandan Vannathan, A.; Thakre, D.; Ali, S.R.; De, M.; Banerjee, A.; Mal, S.Electrochemical properties of two different bisphosphonate-polyoxovanadate derivatives have been studied. Both the compounds are oxovanadate polyanion derivatives having formula (NH4)4[H6(VIVO2)(VV2O5)2{O3P–C(O)(CH2-2-C5NH4)-PO3}2]•9H2O (1) and (NH4)4[H6(VIVO2)(VV2O5)2{O3P–C(O)(CH2-3-C5NH4)-PO3}2]•8H2O (2). Compounds 1 and 2 are isostructural mixed-valent polyoxovanadate structures containing 1-hydroxy-2-(2-pyridyl) ethylidene-1,1-bisphosphonate and 1-hydroxy-2-(3-pyridyl) ethylidene-1,1-bisphosphonate, respectively. Composites of these compounds have been prepared with activated carbon (AC), viz. AC-1 and AC-2 for compounds 1 and 2, respectively. In order to investigate the interaction between the parent compounds with activated carbon, the as prepared composites were further characterized using various analytical techniques, such as Infrared spectroscopy, thermal stability analysis, powder X-ray diffraction, FE-SEM, EDX, and surface adsorption studies. Electrodes from these composites have been prepared by deposition upon carbon cloth, and their electrochemical properties, with respect to the supercapacitance behavior, have been extensively studied. The electrochemical performance of both the composite materials have been tested in an aqueous 0.1 ?M ?H2SO4 electrolytic solution. AC-2 displays the highest specific capacitance of 313 ?F ?g?1 at a current density of 1 ?A ?g?1, along with incredible specific energy and power of 43.56 ?Wh kg?1 and 1999.72 ?W kg-1, respectively. Likewise, AC-1 exhibits a specific capacitance of 212 ?F ?g?1 also at the current density of 1 ?A ?g?1 with a specific energy of 29.45 ?Wh kg?1. The AC-2 electrode, therefore, shows more conducting and lower resistivity. As such, composite AC-2 was observed to light up red, green, and blue color LED bulbs for 71, 70, and 15 ?seconds, respectively, with only 42 ?mg of sample coated on carbon cloth, suggesting a remarkable specific power of that material. Comparatively, the composite AC-1 electrode could light up the red LED bulbs for about 190 ?seconds, albeit with 143 ?mg of sample coated on carbon cloth. As such, AC-2 was also observed to retain 98.71% of the electrode stability after 4500 cycles. © 2021 Elsevier Inc.Item 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 Supercapacitor activity studies of a unique triangular oxo-vanadate-bisphosphonate composite with activated carbon(Springer Science and Business Media Deutschland GmbH, 2022) Thakre, D.; Anandan Vannathan, A.; Banerjee, A.; Mal, S.S.Electrochemical studies have been performed on a hybrid inorganic–organic oxo-vanadate (IV)-bisphosphonate assembly, viz. (NH4)2[H6(VIVO)3(O){O3P-C(OH)(CH2-4-C5NH4)-PO3}3]•26H2O [V3-BP]. The compound has a triangular shaped structure consisting of reduced vanadium (IV) with 1-hydroxo-2-(4-pyridyl) ethylidene-1,1-bisphosphonic acid. Composites of this compound were prepared with activated carbon (AC), viz. AC-V3-BP, and extensively characterized using various analytical techniques (e.g., FT-IR, TGA, P-XRD, FESEM, EDX, and BET) to study the interaction of V3-BP with the activated carbon support. Electrochemical properties of AC-V3-BP were studied, vis-à-vis its supercapacitor behavior, with the electrochemical performance of the composite AC-V3-BP material tested in 0.1 (M) H2SO4 aqueous electrolytic solution. The composite exhibits a specific capacitance of 140.8 F g−1 with a specific energy of 19.56 W kg−1. With such interesting capacitive properties, electrochemical cells prepared with this material were observed to light up red and blue LED bulbs for 90 and 20 s, respectively, suggesting a substantial power density of the materials. The respective electrode prepared from the composite was also observed to retain 79.23% of the electrode stability after 4500 cycles. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.