Faculty Publications
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Item Lower Band Gap Sb/ZnWO4/r-GO Nanocomposite Based Supercapacitor Electrodes(Springer New York LLC barbara.b.bertram@gsk.com, 2019) Brijesh, K.; Nagaraja, H.S.Sb/ZnWO4/r-GO nanocomposite has been prepared by a single step solvothermal method. The crystal structure of the prepared nanocomposite has been characterized using a powder x-ray diffractometer (XRD). The optical properties of the prepared nanocomposite were studied using UV–visible spectroscopy and photoluminescence. The energy band gap of 3.52 eV is obtained for the ZWS-5 nanocomposite using Tauc plots. For both Sb/ZnWO4 and Sb/ZnWO4/r-GO nanocomposite XRD shows the monoclinic Wolframite structure. The supercapacitor performance of the prepared samples was carried out using electrochemical techniques such as cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy. The nanocomposite ZWS-5 exhibits a specific capacitance of 102 F/g, which is higher than pristine ZWS specific capacitance of 64 F/g. Both ZWS and ZWS-5 electrodes show good capacitance retention proficiency even after 1000 cycles. © 2019, The Minerals, Metals & Materials Society.Item ZnWO4/r-GO nanocomposite as high capacity anode for lithium-ion battery(Springer, 2020) Brijesh, K.; Nagaraja, H.S.The pristine ZnWO4 and ZnWO4/r-GO nanocomposite synthesized by the facile solvothermal method were tested as anode materials for lithium-ion battery. Ex situ X-ray photoelectron spectroscopy (XPS) confirms the elemental composition of the pristine ZnWO4 and ZnWO4/r-GO nanocomposite. The ZnWO4/r-GO nanocomposite shows mesoporous nature and exhibits 50.802 m2 g?1 BET specific surface area, which is higher than that of pristine ZnWO4. In addition, the electrochemical property of the pristine ZnWO4 and ZnWO4/r-GO nanocomposite investigated using 2032 half-cell reveals that GO enhances the electrochemical property of the ZnWO4. The ZnWO4/r-GO nanocomposite not only exhibits higher discharge capacity of 1158 mAh g?1 at 100 mA g?1 but also shows longer and stable cycle life at 300 mA g?1 current density. The ZnWO4/r-GO nanocomposite exhibits 80.74% capacity retention even after 500 cycles. The synergetic effect of r-GO and ZnWO4 improves the capacity, columbic efficiency, and stability of the material. The results indicate that ZnWO4/r-GO nanocomposite is an interesting anode material for Li-ion battery with higher capacity complemented with stability compared to pristine ZnWO4. [Figure not available: see fulltext.]. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.Item GeO2/ZnWO4@CNT nanocomposite as a novel anode material for lithium-ion battery(Springer, 2020) Brijesh, K.; Nagaraja, H.S.Single-walled carbon nanotube (SWCNT) wrapped GeO2/ZnWO4 nanocomposite was prepared by single-step solvothermal method. In this work, GeO2/ZnWO4 nanocomposites were prepared by varying the molar percentage of GeO2 and by further adding SWCNT for the composite to boost the electrochemical performance. The prepared GeO2/ZnWO4 nanocomposites and GeO2/ZnWO4@CNT nanocomposite are used as anode material for lithium-ion battery (LIB). As expected, GeO2/ZnWO4@CNT nanocomposite exhibits higher capacities and good rate capability than the GeO2/ZnWO4 nanocomposite. The GeO2/ZnWO4@CNT nanocomposite exhibits 930 mAh g?1 discharge capacity and 533 mAh g?1 charge capacity for the initial cycle at 100 mAh g?1 in the voltage range of 0.01–3 V (vs. Li+/Li). Even at high current density of 500 mAh g?1, GeO2/ZnWO4@CNT nanocomposite shows 231 mAh g?1 and 257 mAh g?1 charge/discharge capacity which are higher than that of GeO2/ZnWO4 nanocomposite. The GeO2/ZnWO4@CNT nanocomposite delivers 75.8% capacity retention and 100% coulombic efficiency even after 400 cycles at 300 mAh g?1. These results direct that GeO2/ZnWO4@CNT nanocomposite is a good negative electrode for lithium-ion battery. [Figure not available: see fulltext.]. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.Item ZnWO4/SnO2 composite for supercapacitor applications(Elsevier B.V., 2020) Vinayaraj, S.; Brijesh, K.; Dhanush, P.C.; Nagaraja, H.S.The pristine ZnWO4 and ZnWO4/SnO2 composite was synthesized by solvothermal method. The crystal structure of the ZnWO4 and ZnWO4/SnO2 composite is determined by powder X-ray diffraction (XRD) pattern. The morphology of the samples investigated using SEM and found to be agglomerated structure. The samples are tested as an electrode material for supercapacitor using electrochemical techniques like cyclic Voltammetry (CV), Galvanostatic Charge-Discharge (GCD) and Electrochemical Impedance Spectroscopy (EIS). The ZnWO4/SnO2 composite reveals 56.7 F/g specific capacitance at 1 mV/s scan rate which is higher than that of pristine material and also ZnWO4/SnO2 composite exhibits good cyclic stability than pure ZnWO4. © 2020 Elsevier B.V.Item Fabrication of AgWO4/CNT nanomaterial for high capacity lithium ion battery(Taylor and Francis Ltd., 2022) Brijesh, K.; Prajil, M.K.; Nagaraja, H.S.Herein, we report the synthesis of AgWO4 nanomaterial (AWN) and Single-walled carbon nanotube (SWCNT) wrapped AgWO4 nanomaterial (AWNC) via the solvothermal method and is used as an anode material for lithium-ion battery (LIB). The AWNC exhibits, 1202 mAh g?1 discharge capacity at 0.1 A g?1 current density with good cyclic stability and 100% columbic efficiency even after 500 cycles. The AWNC electrode shows a reversible capacity of 594, 521, 252, 143 and 84 mAh g?1 at 0.1, 0.2, 0.3, 0.5 and 1 A g?1 respectively. The 543 mAh g?1 reversible capacity recovered at 0.1 A g?1 after cycling at several current densities suggests the good rate performance of the AWNC electrode. The decent electrochemical performance of the AWNC is due to the synergetic effect between AgWO4 and SWCNT. AWNC shows improved rate capability, better cycling stability, reversible capacity and capacity retention than that of AWN. These results suggest that AWNC is an exciting anode material for LIB. © 2020 Informa UK Limited, trading as Taylor & Francis Group.Item Enhanced Electrochemical Performance of Low-Content Graphene Oxide in Porous Co3O4 Microsheets for Dual Applications of Lithium-Ion Battery Anode and Lithium-Ion Capacitor(Springer, 2024) Lakshmi Sagar, G.; Brijesh, K.; Mukesh, P.; Amudha, A.; Bhat, K.S.; Nagaraja, H.S.The enhancement of electrochemical performance in lithium-ion battery (LIB) anode materials through nanostructures is of paramount importance, facilitated by the synergistic integration of these unique architectures with active materials, which increases the availability of active sites and decreases the diffusion path for lithium ions. In this investigation, we successfully synthesized cobalt oxide (Co3O4) microsheets composed of small nanoparticles (measuring 28–33 nm), employing a straightforward hydrothermal process followed by annealing. Furthermore, to enhance the composite’s ability to endure volume changes and increase its electrical conductivity, we created a Co3O4/reduced graphene oxide (rGO) composite embedding a judicious amount of graphene oxide (GO). This engineered composite exhibited remarkable specific discharge capacity of 1081 mAh g−1 at 100 mA g−1, a substantial improvement over the pristine material’s capacity of 718 mAh g−1. The composite demonstrated reduced irreversible capacity loss relative to the pristine counterpart and approached a reversible capacity of nearly 99%. Even after 400 cycles under the demanding conditions of high current density of 500 mA g−1, the composite managed to retain 81% of its initial capacity, underscoring its exceptional cycling stability. Moreover, the application of the Co3O4/rGO//carbon black (CB) assembly in lithium-ion capacitors (LIC) yielded notable energy density of 15.6 Wh kg−1 at elevated power density of 1007 W kg−1. These LIC devices demonstrated robust cyclic stability across extended cycles, sustaining 56% of their initial capacity after 2000 cycles while operating at a current density of 2 A g−1. Graphical Abstract: [Figure not available: see fulltext.]. © 2024, The Minerals, Metals & Materials Society.Item Impact of copper doping on the electrochemical response of MnSe2 as anode for lithium-ion battery(Springer, 2024) Mukesh, P.; Lakshmi Sagar, G.; Brijesh, K.; Kumawat, S.; Hegde, A.; Kumar, A.; Nagaraja, H.S.Transition Metal Chalcogenides (TMC), due to their unique physicochemical properties, are studied in various fields and have potent applications in energy storage applications. This work is based on the synthesis and characterization of copper-doped manganese di-selenide and the effect of its doping on electrochemical performance as anode material for lithium-ion battery applications using the solvothermal method. The characterization techniques used are X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy, XPS, UV–visible absorption spectroscopy, and electrochemical analysis. The XRD data confirms the formation of MnSe2 exhibiting Cubic crystal geometry. The FESEM images show the micro-cube-like structure with agglomerated nanocluster nanostructures on the surface with a dimension of 100–200 nm. The doping of the copper has decreased the band gap of the MnSe2, as studied by the UV–visible absorption spectrum. The electrochemical performance is analyzed as anode material for lithium-ion batteries. The charge/discharge measurements show a specific capacity of 706 mAh g−1 as the initial discharge capacity and 336 mAh g−1 as the initial charge capacity at 0.1 A g−1 current density. Meanwhile, 3% Copper-doped MnSe2 showed a better specific capacity of 878 mAh g−1 as the initial discharge capacity and 461 mAh g−1 as the initial charge capacity at 0.1 A g−1 current density. Cyclic stability, rate capability, and electrochemical impedance spectroscopy were performed, and it shows that 3% copper-doped MnSe2 has good stability and better conductivity and charge kinetics, indicating copper doping has enhanced the electrochemical performance of pristine MnSe2. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.