Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
10 results
Search Results
Item Effect of synthesis method on structural properties and soot oxidation activity of gadolinium-doped ceria(Springer International Publishing kasia@cesj.com, 2018) Anjana, A.P.; Gadiyar, H.J.; Surendran, M.; Rao, A.S.; Prasad Dasari, H.P.; Harshini, H.; Babu, G.U.B.Abstract: EDTA–citrate complex and solvothermal methods were adopted for the synthesis of gadolinium-doped ceria (GDC) (Ce0.9Gd0.1O2) solid solution, and the obtained GDC sample is tested for soot oxidation activity. Based on XRD results, it was evident that the reactive facet planes of {100} and {110} were highly intense [intensity ratio (%) of (200)/(100) (34.2%) and (220)/(111) (51.2%)] for GDC prepared by the EDTA–citrate method in comparison with the solvothermal method, and this highly intense reactive facet plane correlates to the lower energy for oxygen vacancy formation. Apart from the smaller crystallite size (10 nm) the GDC sample prepared by the EDTA–citrate method displayed lower band gap energy (2.99 eV), higher ratio of reducibility (45.45%) and lower binding energy (528.8 eV) for surface-adsorbed oxygen. The GDC obtained by EDTA–citrate method displayed a better soot oxidation activity (T50 = 468 °C) than compared to the GDC obtained by solvothermal method (T50 = 500 °C). The obtained results significantly show that the synthesis method plays a crucial role in controlling the structural properties and in enhancing the soot oxidation activity. © 2018, Institute of Chemistry, Slovak Academy of Sciences.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 Eco-friendly synthesis of porous graphene and its utilization as high performance supercapacitor electrode material(Elsevier Ltd, 2019) Sethi, M.; Bantawal, H.; Shenoy, U.S.; Bhat, D.K.The successful application of porous graphene (PG) is hindered due to the lack of efficient and cost-effective method for its synthesis. Herein, we report a facile and eco-friendly method to produce PG through a low temperature solvothermal method. The structural and morphological characteristics of PG samples were investigated thoroughly. The as synthesized material is found to be a few layers thick (?4–6 layers) with a surface area of 420 m2 g?1 and consisting of hierarchical pores on the surface of the sheets. A high specific capacitance of 666 F g?1 was obtained at a scan rate of 5 mV s?1, apart from longer cyclic stability with 87% retention of initial capacitance value after 10000 cycles for the PG 28 sample. The fabricated supercapacitor displayed an energy density of 26.3 Wh kg?1 and power density of 6120 W kg?1. Density functional theory calculations were also carried out to qualitatively support the enhanced capacitance by providing theoretical insight from electronic structure and density of states of PG. These results open a new avenue for greener synthesis of high-quality PG using environmentally friendly solvents, without the use of toxic chemicals, for excellent supercapacitor performance. © 2019 Elsevier B.V.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 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 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 Hassle-free solvothermal synthesis of NiO nanoflakes for supercapacitor application(Elsevier B.V., 2021) Sethi, M.; Shenoy, U.S.; Bhat, D.K.A mixed solvent solvothermal approach was employed for the synthesis of NiO (NO) nanostructures under a low temperature route. The nanoflakes when studied for its electrochemical performance in a 3-electrode method in aqueous 2 M KOH revealed a high capacitance value of 305.0 F g?1 at a scan rate of 5 mV s?1 apart from good rate capability, cyclic stability and coulombic efficiency. The fabricated symmetrical supercapacitor device also showed good electrochemical performance of pseudocapacitive nature with a high power density of 8000.0 W kg?1. The extent of surface sites taking part in the electrochemical processes reveals the enhanced performance is due to the high surface area of NO with a mesoporous structure. The enhanced conductivity of the nanoflakes also provided an unhindered path way for the ionic transport. The promising results reveal that the synthetic technique employed could be extended to other oxides as well. © 2021 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 conductivity of Bi2O3 through ‘Fe3+’ doping for pseudocapacitor application(Springer Science and Business Media Deutschland GmbH, 2025) G, L.S.; Bhat, K.S.; Mukesh, P.; Hegde, A.P.; Kumar, A.; Brijesh, K.; Nagaraja, H.S.Binary metal oxides have emerged as pSromising materials for advanced electrochemical energy storage systems due to their superior performance characteristics. In this study, we focus on bismuth oxide (Bi?O?), a material renowned for its high theoretical capacity, wide potential range, and exceptional power density, as a potential candidate for supercapacitors. Iron doping was employed as a strategy to enhance its electrochemical performance and modulate the band gap, thereby improving conductivity and charge storage efficiency. Fe-doped bismuth oxide (Fe-Bi?O?) was synthesized via a solvothermal method with varying iron concentrations (2%, 4%, and 6%), followed by annealing. The pure and iron-doped bismuth oxide samples revealed a combination of monoclinic and cubic phases and a prominent micro-sheet architecture. The introduction of iron doping led to a noticeable reduction in the band gap, highlighting its role in fine-tuning the electronic properties for enhanced energy storage capabilities. The electrochemical evaluation highlighted the 4% Fe-Bi?O? sample as the optimal composition, achieving a remarkable specific capacity of 904 F g?1, a substantial improvement over 101 F g?1 for pristine Bi?O?, at 1 A g?1 in a 2 M KOH electrolyte. Moreover, this sample exhibited outstanding cyclic stability, retaining 104 F g?1 after 2000 cycles at 10 A g?1. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.