Browsing by Author "Krishna Bhat, D."

Filter results by typing the first few letters
Now showing 1 - 6 of 6
  • No Thumbnail Available
    Item
    Electrochemical study of graphene-NiCo2O4 nanocomposite prepared through solvothermal approach
    (American Institute of Physics Inc. subs@aip.org, 2019) Sethi, M.; Krishna Bhat, D.
    A green approach was employed for the synthesis Graphene-NiCo2O4 nanocomposite and its electrochemical property has been studied. The formation of phase and morphology was studied by diffraction and microscopic analysis. The prepared material was studied as an electrode material for supercapacitor application in a 2 M KOH electrolyte. In order to examine the electrochemical behavior of the prepared material cyclic voltammetry (CV), Galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) measurements were carried out in a 3-electrode system. Electrochemical studies revealed a high specific capacitance of 242 F g-1 and 165 F g-1 were obtained at a high scan rate of 10 mV s-1 and at an applied current density of 0.5 A g-1, respectively. A high initial capacitance retention value and coulombic efficiency of about 96% and 98% was retained after a long 1000 discharge cycles. Hence, the prepared material can be a potential candidate for high performance supercapacitor applications. © 2019 American Institute of Physics Inc.. All rights reserved.
  • No Thumbnail Available
    Item
    h-MoO 3 /Activated carbon nanocomposites for electrochemical applications
    (Institute for Ionics ww@tf.uni-kiel.de, 2019) Sangeetha, D.N.; Krishna Bhat, D.; Muthu, M.
    MoO 3 nanorods were synthesized through the microwave method and the nanocomposites of MoO 3 /activated carbon were prepared for supercapacitor and hydrogen evolution reaction (HER). The XRD pattern revealed that the prepared MoO 3 has a hexagonal phase (h-MoO 3 ). The as-prepared h-MoO 3 was composited with activated carbon (AC) and tested for supercapacitor studies. The fabricated supercapacitor exhibited an appreciable specific capacitance, power density, and energy densities. Further, dedoping of nitrogen in the doped AC creates defects on AC (DAC). These DAC/MoO 3 nanocomposites were prepared and tested for its electrocatalytic activity towards hydrogen evolution reactions. DAC/MoO 3 nanocomposite showed much higher electrocatalytic activity than the neat MoO 3 . [Figure not available: see fulltext.]. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.
  • No Thumbnail Available
    Item
    Improving hydrogen evolution reaction and capacitive properties on CoS/MoS2 decorated carbon fibers
    (Elsevier Ltd, 2020) Sangeetha, D.N.; Krishna Bhat, D.; Senthil Kumar, S.; Muthu, M.
    We report a facile method to transform abundantly dumped banana stem fibers into carbon fibers (CFs) useful for energy applications. The CFs surface area is increased by varying the quantity of KOH activation to 488 m2g-1. The solvothermal method is used to synthesize CoS, CoS/MoS2 and also grown on the activated carbon fibers (ACFs). Nano nodules of CoS arranged into sheets and layers of MoS2 stacked together were found in FESEM analysis. The morphology of the CoS/MoS2 differs when grown on ACFs. The growth of CoS/MoS2 along the ACFs length prevents any stacking of the pseudocapacitance materials. The ternary composite ACFs/CoS/MoS2 exhibits superior supercapacitor behavior as well as hydrogen evolution reaction (HER) due to the synergetic effect of the conducting ACF surface and redox active CoS/MoS2. A maximum specific capacitance of 733 Fg-1, energy and power density of 33 WhKg?1 and 999 WKg-1 respectively are obtained. A low Tafel slope value of 61 mVdec?1 is obtained for the ACFs/CoS/MoS2 ternary composite electrode. The present work therefore offers a fresh insight into the effective conversion of waste materials into electrode material for energy storage and conversion applications. © 2019 Hydrogen Energy Publications LLC
  • No Thumbnail Available
    Item
    Novel NiWO4-ZnO-NRGO Ternary Nanocomposites with Enhanced Photocatalytic Activity
    (Elsevier Ltd, 2018) Mohamed, M.; Krishna Bhat, D.
    A novel NiWO4-ZnO-NRGO ternary nanocomposite was efficiently synthesized via a facile, fast and easy microwave irradiation technique and its capability to photodegrade organic dye in aqueous solution was investigated. The products were characterized through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy, photoluminescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy (DRS) techniques. The photocatalytic activity was evaluated by estimating the extent of photodegradation of methylene blue (MB) under irradiation of visible light source, which showed 9 times enhancement for the ternary composites compared to that for pure NiWO4. The outcomes reveal that the novel NiWO4-ZnO-NRGO ternary nanocomposite could be a highly efficient visible light photocatalyst for the removal of environmental contaminants in wastewater. © 2018 Elsevier Ltd.
  • No Thumbnail Available
    Item
    SnO2 nanoparticles functionalized MoS2 nanosheets as the electrode material for supercapacitor applications
    (Institute of Physics Publishing helen.craven@iop.org, 2019) Prabukumar, C.; Mohamed, M.; Krishna Bhat, D.; Udaya Bhat, K.
    Tin oxide (SnO2) nanoparticles undergo the volume expansion during an electrochemical cycle. This volume expansion leads to discontinuities in the form of microcracks in the electrode material. The problem of charge transportation associated with this microcracking limits the application of SnO2 in the energy storage application such as supercapacitors. The present work approached to solve this problem by incorporating the MoS2 nanosheets along with the SnO2 nanoparticles. The SnO2 nanoparticles are functionalized onto the surface of the MoS2 nanosheets by the ligand exchange process. The MoS2 nanosheets act as the support material for the SnO2 nanoparticles. The electrode material prepared using SnO2 nanoparticles and nanocomposite of SnO2 functionalized MoS2 nanosheets are tested by cyclic voltammetry and galvanostatic charge-discharge measurements. The specific capacity of the MoS2-SnO2 nanocomposite is calculated to be 61.6 F g-1 which is 4.4 fold higher than that of bare SnO2 nanoparticles. The improvement in the electrochemical performance of SnO2 is attributed to the high surface area and the charge transportation provided by the MoS2 nanosheets. © 2019 IOP Publishing Ltd.
  • No Thumbnail Available
    Item
    Supercapacitor studies of activated carbon functionalized with poly(ethylene dioxythiophene): Effects of surfactants, electrolyte concentration on electrochemical properties
    (Elsevier B.V., 2020) Sudhakar, Y.N.; Muthu, M.; Krishna Bhat, D.; Karazhanov, S.; Raghu, R.
    Electropolymerization of poly(ethylene dioxythiophene) (PEDOT) on activated carbon (AC) was performed using different surfactants such as anionic surfactant (sodium dodecyl sulfate), protonic surfactant (camphor sulphonic acid) and non-ionic surfactant (Triton) in 0.1 M H2SO4. The effects of concentration of different surfactants for electrodeposition of PEDOT on AC were analyzed using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and SEM techniques. Supercapacitors (SC) were fabricated using AC/PEDOT composite electrodes and 0.1 M H2SO4 as an electrolyte. The specific capacitance (Cs) values were calculated using CV at different concentrations of surfactants, electrolytes and variation of potential. The electrolyte containing 0.1 M H2SO4 and 0.02 M camphor sulphonic acid showed to have the highest specific capacitance value of 240 Fg?1 than other surfactant based SCs. Galvanostatic charge/discharge at varying current density were performed on SCs containing different surfactant based electrodes to study their cyclic stability. © 2020