Faculty Publications
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Item Electrolytic Synthesis and Characterization of Electrocatalytic Ni-W Alloy(Springer New York LLC barbara.b.bertram@gsk.com, 2015) Elias, L.; Scott, K.; Hegde, A.Inspired by the more positive (about 0.38 V nobler) discharge potential of hydrogen on Ni-W alloy compared to that on both Ni and W, a Ni-W alloy has been developed electrolytically as an efficient electrode material for water electrolysis. The deposition conditions, for peak performance of the electrodeposits for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1.0 M KOH medium have been optimized. Electrocatalytic activity of the coatings, deposited at different current densities (c.d.’s) for water splitting reactions of HER and OER was tested by cyclic voltammetry and chronopotentiometry. It was found that Ni-W alloys deposited, at 4.0 A/dm2 (having about 12.49 wt.% W) and 1.0 A/dm2 (having about 0.95 wt.% W) are good electrode materials as cathode (for HER) and anode (for OER), respectively. A dependency of the electrocatalytic activity for HER and OER with relative amount of Ni and W, in the deposit was found. The variation of electrocatalytic activity with W content showed the existence of a synergism between high-catalytic property of W (due to low hydrogen overvoltage) and Ni (having increased adsorption of OH? ions), for hydrogen (as cathode) and oxygen (as anode) evolution, respectively. Electrocatalytic activities of the coatings, developed at different c.d.’s were explained in the light of their phase structure, surface morphology, and chemical composition, confirmed by XRD, FESEM, and EDX analysis. The effect of c.d. on thickness, hardness, composition, HER, and OER was analyzed, and results were discussed with possible mechanisms. © 2015, ASM International.Item Effect of current density and electrochemical cycling on physical properties of silicon nanowires as anode for lithium ion battery(Elsevier Inc. usjcs@elsevier.com, 2017) Ramesh, R.; H.S., N.Herein, we successfully fabricated vertically aligned silicon nanowires (Si NWs) via an electrochemical etching of n-type (100) silicon at different high current densities. The morphology of the prepared Si NWs was studied using SEM, FFT analysis and WSxM software. From FTIR spectroscopy analysis, the silicon dangling bonds of the as-prepared Si NWs layer have large amount of hydrogen to form weak Si[sbnd]H bonds. The blue shift was observed in Photoluminescence due to decrease in the size of silicon crystallites, the crystallite size in the Si NWs varied from 5.9 nm to 4.8 nm depending on the current density. The contact angle varied from 74.7° to 149.1°. From the wettability studies, the surface nature of the Si NWs was converted from hydrophilic to hydrophobic when the current density increased. The obtained Si NWs were used as an anode in lithium ion cell. The charge capacity of the anode is ~ 3452.47 mAh g? 1 at the first cycle with the coulombic efficiency over 85.8%, and faded to 1134.34 mAh g? 1 with coulombic efficiency over 81.6% after the 12th cycle at a current rate of 1C. Scanning electron microscopy and selected area electron diffraction are performed to study the morphology and crystalline structure of the anode, respectively. The dislocation density decreased from 46.2 × 1015 m? 2 to 0.06 × 1015 m? 2 and the surface area decreased from 1.5 × 103 ?m2 to 0.05 × 103 ?m2 with cycle number increased from 1 to 102 whereas the band gap increased from 2.2 eV to 2.9 eV. The above observations are well correlated. © 2017 Elsevier Inc.Item Stone-Wales Defect Induced Performance Improvement of BC3 Monolayer for High Capacity Lithium-Ion Rechargeable Battery Anode Applications(American Chemical Society, 2020) Thomas, S.; Madam, A.K.; Asle Zaeem, M.A.First-principles density functional theory (DFT) computations were adopted to assess the potential application of a boron carbide (BC3) monolayer with point and topological defects as an anode material in alkali metal-based lithium (Li) ion rechargeable batteries. Results show that point defects (mono and bi vacancies) induce a large structural deformation upon Li intercalation which restricts their use for anode application. However, the Stone-Wales defect filled BC3 monolayer shows high structural stability with a negative Li binding energy of -1.961 eV in comparison with -0.930 eV of its pristine form. It is also noticed that after adsorbing the Li atom, the semiconducting characteristics of both the pristine and Stone-Wales defect filled BC3 monolayers are transformed into metallic, electrically conductive states. More importantly, the Li alkali metal atom shows fast diffusion on the surfaces of both the pristine and the Stone-Wales defect filled BC3 monolayers with low energy barriers of 0.34 and 0.33 eV, respectively. Besides, both the pristine and Stone-Wales defect filled BC3 monolayers exhibit high theoretical specific capacities of 1144 and 1287 mAhg-1, which are much higher than that of a traditional graphite anode and stand among the highest values of anode materials detailed in literature. The Li alkali metal intercalated monolayers BC3 show small average open-circuit voltages of 0.485 and 0.465 V for pristine and Stone-Wales defect cases, respectively. On the basis of the aforementioned details, the present study suggests that the Stone-Wales type topological defect incorporated BC3 monolayer is a promising anode material for Li-ion based rechargeable batteries with high storage capacity, low Li diffusion energy barrier, and low average open-circuit voltage. © 2020 American Chemical 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 Monoclinic Wolframite ZnWO4/SiO2 nanocomposite as an anode material for lithium ion battery(Elsevier B.V., 2020) Brijesh, K.; Dhanush, P.C.; Vinayraj, S.; Nagaraja, H.S.Herein, we report the preparation and characterization of the ZnWO4 and ZnWO4/SiO2 nanocomposite. The ZnWO4/SiO2 nanocomposite exhibits 570 mAh g?1 discharge capacity and 314 mAh g?1 charge capacity at 10 mA g?1 for the primary cycle. The increasing amount of SiO2 in the ZnWO4/SiO2 nanocomposite increases the overall performance of the composite. The synergetic effect between the ZnWO4 and SiO2 enhances the rate capability, specific capacity, cycle stability and coloumbic efficiency of the composite. The good electrochemical performance of ZnWO4/SiO2 nanocomposite makes it a promising anode for Lithium ion battery. © 2020 Elsevier B.V.Item ZnWO4/SnO2@r-GO nanocomposite as an anode material for high capacity lithium ion battery(Elsevier Ltd, 2020) Brijesh, K.; Vinayraj, S.; Dhanush, P.C.; Bindu, K.; Nagaraja, H.S.Lithium ion battery (LIB) is widely used energy storage device. Herein, we report the preparation of ZnWO4/SnO2 nanocomposite and ZnWO4/SnO2@r-GO nanocomposite via solvothermal method. The structural, elemental and morphological properties of the prepared samples are characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDAX), high-resolution transmission electron microscopy (HR-TEM), Brunauer-Emmett-Teller (BET) measurements, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) techniques. The prepared samples are tested as an anode for LIB. The ZnWO4/SnO2 (5%) nanocomposite delivers initial discharge capacity of 882 mAh g?1 at a current density of 100 mA g?1, while, the specific capacity increases with the increase of SnO2 upto 10% tested in present case. Further, ZnWO4/SnO2@r-GO nanocomposite exhibits a discharge capacity of 1486 mAh g?1 which is higher than that of ZnWO4/SnO2 nanocomposite. In addition, after 500 cycles ZnWO4/SnO2@r-GO nanocomposite exhibits 89.8% cycle life and 98% of discharge capacity retention. These results indicate that, ZnWO4/SnO2@r-GO nanocomposite is a promising anode material for LIB. © 2020 Elsevier LtdItem 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 Mechanically robust, self-healing graphene like defective SiC: A prospective anode of Li-ion batteries(Elsevier B.V., 2021) Manju, M.S.; Thomas, S.; Lee, S.U.; Ajith, K.M.First-principles density functional theory (DFT) computations are carried out to assess the potential application of a monolayer Silicon carbide (SiC) with the presence of topological and point defects. Results show that the unstable binding of pristine SiC makes it a poor candidate for the anode material. However, the introduction of vacancy and Stone-Wales type topological defect in SiC possesses a stable Li binding property. Besides, all the defective configuration showed higher electrical conductivity, superior mechanical robustness and stable formation energy. We also observed a structural reorientation from point to topological defect with a 5-8-5 ring formation in C and Si-C bi-vacancy and a Li-mediated phenomenon in the case of Si bi-vacancy. All the configurations under consideration exhibited low open-circuit voltage (0.1 V), a low Li diffusion barrier (~0.77 eV), and a fairly high specific capacity (501 mAh/g for Stone-Wales) compared to the conventional graphite anode. Besides, the ab initio molecular dynamics calculations confirmed the thermal stability and structural integrity of the defective SiC. Based on these findings, the present study suggests that SiC with a Stone-Wales defect can be a forthcoming candidate for the anode of LIBs. © 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 Enhancing the electrochemical performance of ZnO anode by novel additive of MoS2–SnO2 nanocomposite for the zinc alkaline battery application(Springer, 2022) Prabukumar, C.; Meti, S.; Bhat K, U.K.ZnO nanorods and ZnO microrods are synthesized as the anode material for the Zn alkaline battery application. The present work studies the electrochemical performance of ZnO with regard to its size, morphology and MoS2–SnO2 nanocomposite as its additive towards the alkaline battery application. The properties, such as oxidation–reduction reaction, anti-corrosion behaviour, charge-transfer resistance and suppression of hydrogen evolution reaction (HER), are studied in detail. The structural characterization of ZnO samples is performed by using X-ray diffractometry. The morphological analysis of ZnO and MoS2–SnO2 nanocomposite is performed by using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), respectively. The atomic absorption spectroscopy (AAS) is employed to determine the solubility of ZnO samples in KOH solution. The electrochemical properties of the bare ZnO and the ZnO with MoS2–SnO2 additive (MoS2–SnO2/ZnO) samples are characterized by using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), cathodic polarization and Tafel polarization techniques. The ZnO with nanorod morphology shows better electrochemical performance than ZnO microrods and ZnO nanoparticles with sphere-like or plate-like morphology. The addition of MoS2–SnO2 nanocomposite with the ZnO improved the electrochemical activity, suppressed the HER activity and improved the anti-corrosion behaviour of the ZnO samples. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.