Faculty Publications

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Subject: search.filters.subject.Supercapacitor application

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    Effect of surfactant on high capacitance of galvanostatically deposited MnO2
    (Elsevier B.V., 2012) Suhasini; Hegde, A.
    Manganese dioxide has been galvanostatically deposited on stainless-steel substrate from an aqueous acidic solution of manganese sulphate (1 M) in presence of a surface active agent (surfactant), namely, sodium lauryl sulphate (SLS), for supercapacitor applications. The deposits have been developed under different conditions of SLS and their specific capacitance is measured by cyclic voltammetry (CV) and also by galvanostatic charge/discharge cycle. The oxide film (?0.1 mg cm-2) anodized from the manganese solution at 2.0 mA cm-2 has shown the highest specific capacitance of 255.8 F g -1, at scan rate of 10 mV s-1. It is observed that the capacitance increased by about 40% compared to the oxide prepared in the absence of SLS. Improved specific capacitance is due to the effect of the surfactant molecules in the deposit, causing high surface area of the deposit. The deposit is found to display good cycleability, even up to 1500 cycles. The structure and surface morphology of the deposits have been studied by means of X-ray diffraction (XRD) analysis and Scanning Electron Microscopy (SEM). XRD study reveals that crystallinity of the deposit with SLS remains unchanged, both are amorphous in nature. The surface area of the deposit is found to increase considerably due to the effect of SLS, as evident by SEM study.© 2012 Elsevier B.V. All rights reserved.
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    Magnetron sputtered MoO3/carbon nanotube composite electrodes for electrochemical supercapacitor
    (Elsevier B.V., 2013) Aravinda, L.S.; Nagaraja, K.K.; Bhat, K.; Badekai Ramachandra, B.
    Molybdenum oxide (MoO3) has been deposited on multiwalled carbon nanotubes (MWCNTs) using DC reactive magnetron sputtering of molybdenum for supercapacitor applications. The deposits of MoO3 have been developed under different intervals of time. The structure and surface morphology of the deposits have been characterized by means of X-ray diffraction (XRD) analysis and field emission scanning electron microscopy (FESEM). X-ray diffraction peaks of the composite films reveal the formation of crystalline structure of MoO3. The electrochemical performance of the composite films was studied using cyclic voltammetry (CV), galvanostatic charge discharge and electrochemical impedance spectroscopy measurements. The composite film exhibits maximum specific capacitance of 70 F g-1 at a scan rate of 10 mV s-1 in 1 M Na2SO4 electrolyte. The nanocomposite electrode material shows specific capacitance which is almost four fold increase with respect to that of bare MWCNTs. The effect of coating duration on specific capacitance has been studied. The nanocomposite film is found to display good cycleability, even up to 1000 cycles. © 2013 Elsevier Inc. All rights reserved.
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    ZnO/carbon nanotube nanocomposite for high energy density supercapacitors
    (2013) Aravinda, L.S.; Nagaraja, K.K.; Nagaraja, H.S.; Bhat, K.; Badekai Ramachandra, B.
    A facile, green and highly efficient method for the decoration of carbon nanotubes with ZnO was developed for the fabrication of binder-free composite electrode for supercapacitor applications. The nano composite was prepared by using reactive magnetron sputtering in Ar/O2 environment. This approach leads to more uniform coating with tuneable thickness, which alters the electrochemical performance of the nano composite electrodes. The structure and surface morphology of the composite film have been studied by means of X-ray diffraction (XRD) analysis, scanning electron microscopy and field emission scanning electron microscopy (FESEM). The XRD study reveals the formation of Wurtzite ZnO structure. The electrochemical performance of nano composite electrode was investigated using cyclic voltammetry, chronopotentiometry and electrochemical impedance measurements in non-aqueous electrolyte. The nano composite electrode shows significant increase in the specific capacitance up to 48 F g-1 with an energy density 13.1 Wh kg-1 in the potential range -2 V to 1 V. © 2013 Elsevier Ltd. All rights reserved.
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    Binder free MoO3/multiwalled carbon nanotube thin film electrode for high energy density supercapacitors
    (2013) Aravinda, L.S.; Bhat, K.; Badekai Ramachandra, B.
    MoO3/multiwalled carbon nanotube (MWCNT) composites were prepared by Magnetron sputtering in Ar/O2 atmosphere. This will provide a greener alternative for the fabrication of binder free composite electrode for supercapacitor applications. MWCNT provides good support for the growth of MoO3 thin films. This integrated composite electrode exhibited specific capacitance of 93 F g-1 and a corresponding energy density of 7.28 Wh kg-1 in non-aqueous electrolyte, which is almost fourfold increase compared to the bare MWCNT. Also the electrode maintains high power density of 4930 W kg-1 at high current rates, suggesting a potential energy storage material for portable and consumer electronics. © 2013 Elsevier Ltd. All rights reserved.
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    Activated carbon derived from non-metallic printed circuit board waste for supercapacitor application
    (Elsevier Ltd, 2016) Rajagopal, R.R.; Aravinda, L.S.; Rajarao, R.; Badekai Ramachandra, B.R.; Sahajwalla, V.
    Activated carbons (ACs) have been synthesized by using waste PCBs via physical activation subsequent to pyrolysis processes. The physical and chemical properties of the produced activated carbons were studied using nitrogen adsorption, FT-IR spectroscopy, RAMAN spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy techniques. Among the synthesized ACs, AC with the highest surface area of 700 m2 g-1 produced at 850 °C for a time interval of 5 h was subjected to electrochemical studies. Capacitance behaviour of the obtained AC sample has been evaluated using cyclic voltammetry (CV), galvanostatic charge-discharge (GC-D) measurements and electrochemical impedance spectroscopy (EIS) technique. Specific capacitance (Cspec) values vary from 220, 185 and 156 F g-1 for corresponding scan rate of 30, 50 and 100 mV s-1 respectively. The well-developed surface area properties and good capacitance values associated with nitrogen functionalities indicates the AC developed is a good and suitable candidate for the supercapacitor fabrication. © 2016 Elsevier Ltd.
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    Microwave assisted growth of stannous ferrite microcubes as electrodes for potentiometric nonenzymatic H2O2 sensor and supercapacitor applications
    (Elsevier Ltd, 2016) Bindu, K.; Sridharan, K.; Ajith, K.M.; Lim, H.N.; Nagaraja, H.S.
    Electrochemical sensors and supercapacitors are two noteworthy applications of electrochemistry. Herein, we report the synthesis of SnFe2O4 microcubes and Fe2O3 nanorods through a facile microwave assisted technique which are employed in fabricating the electrodes for nonenzymatic hydrogen peroxide (H2O2) sensor and supercapacitor applications. SnFe2O4 microcubes exhibited an enhanced specific capacitance of 172 Fg?1 at a scan rate of 5 mVs?1 in comparison to Fe2O3 nanorods (70 Fg?1). Furthermore, the H2O2 sensing performance of the fabricated SnFe2O4 electrodes through chronopotentiometry studies in 0.1 M PBS solution (at pH 7) with a wide linear range revealed a good sensitivity of 2.7 mV ?M?1 ?g?1 with a lowest detection limit of 41 nM at a signal-to-noise ratio of 3. These results indicate that SnFe2O4 microcubes are excellent materials for the cost effective design and development of efficient supercapacitors as well as nonenzymatic sensors. © 2016 Elsevier Ltd
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    Microwave assisted synthesis of rGO/ZnO composites for non-enzymatic glucose sensing and supercapacitor applications
    (Elsevier Ltd, 2017) Moolayadukkam, M.; Dhanush, S.; Rossignol, F.; Nagaraja, H.S.
    Zinc oxide (ZnO) and Graphene Oxide (GO) are known to show good electrochemical properties. In this paper, rGO/ZnO nanocomposites have been synthesised using a simple microwave assisted method. The nanocomposites are characterized using XRD, Raman, SEM and TEM. XRD reveals the wurtzite structure of ZnO and TEM shows the heterogeneous nucleation of ZnO nanocrystals anchored onto graphene sheets. The electrochemical properties of the rGO/ZnO nanocomposite enhanced significantly for applications in glucose sensors and supercapacitors. The non-enzymatic glucose sensor of this nanocomposite tested using cyclic voltammetry (CV) and chronoamperometry, exhibits high sensitivity (39.78 mA cm?2 mM?1) and a lower detection limit of 0.2 nM. The supercapacitor electrode of rGO/ZnO nanocomposite exhibits a significant increase in specific capacitance. © 2017 Elsevier Ltd and Techna Group S.r.l.
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    Facile in-situ single step chemical synthesis of reduced graphene oxide-copper oxide-polyaniline nanocomposite and its electrochemical performance for supercapacitor application
    (Elsevier Ltd, 2017) Viswanathan, V.; Nityananda Shetty, A.
    Reduced graphene oxide (rGO)-copper oxide-polyaniline nanocomposites were synthesized by facile in-situ single step synthesis method with different weight ratio of polyaniline at fixed weight ratios of copper oxide and reduced graphene oxide (rGO); and characterized by IR spectroscopy, powder XRD, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The electrochemical performances of as synthesized composites were studied using two electrode system in 2 M Na2SO4 as electrolyte by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques. The composite with a weight of 300 mg of Polyaniline (PANI), corresponding to the composition (wt %) of rGO6.6%: Cu2O/CuO13.40%: PANI80% (GCP-300) exhibited superior electrochemical characteristics with specific capacitance of 213.20 F g?1, energy density of 18.95 W h kg?1, power density of 545.79 W kg?1, columbic efficiency of 91% and rendered 97.6% of retention of its initial capacitance up to 5000 charge-discharge cycles. The performance is superior to those of binary combinations of constituent materials viz., reduced graphene oxide (rGO), copper oxide and polyaniline, which is attributed to the extent of integration of afore mentioned materials. © 2017 Elsevier Ltd
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    Effect of oxygen substitution and phase on nickel selenide nanostructures for supercapacitor applications
    (Institute of Physics Publishing helen.craven@iop.org, 2018) Bhat, K.S.; Nagaraja, H.S.
    Electrochemical supercapacitors are the eminent technology for the progress of energy storage devices. The current manuscript deals with the formation of oxygen substituted nickel selenide nanostructures and their use as active electrode material for supercapacitor, expecting an enhanced performance owing to their sheet-like geometry, high specific surface area and porous assembly. In this context, Ni(OH)2 (nickel hydroxide) nanostructures were synthesized employing one-pot hydrothermal method and the ion-exchange reaction of Ni(OH)2 nanostructures with selenium resulted in cubic-NiSe2 (nickel selenide) nanostructures. Further, annealing NiSe2 nanostructures at intermediate pressure (10-3 Torr) has realized the partial oxygen substitution in place of selenium, resulting in NiSe/NiO nanostructures along with phase change from cubic-NiSe2 to hexagonal-NiSe. Supercapacitor electrodes fabricated using NiSe/NiO nanostructures delivered the specific capacitance of 83.5 F g-1 at the scan rate of 2 mV s-1, which is surprisingly more than a double as compared with pristine NiSe2 electrodes (37.4 F g-1). Annealing at intermediate pressure and high temperature significantly enhanced the specific capacitances of the nanostructured electrodes and also accompanied with the good capacitance retention of 94% for 5000 CV cycles. © 2018 IOP Publishing Ltd.
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    Facile solvothermal synthesis and high supercapacitor performance of NiCo2O4 nanorods
    (Elsevier Ltd, 2019) Sethi, M.; Bhat, D.K.
    NiCo2O4 nanorod arrays were synthesized employing a facile low-temperature solvothermal approach, followed by post-calcination treatment. The structural, morphological and elemental characterizations were done by diffraction, microscopic and spectroscopic techniques. The prepared sample was studied as an active electrode material for supercapacitor application in 2 M KOH aqueous electrolyte. The cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectral (EIS) studies were carried out to know the electrochemical activity of the prepared material. From the CV study, a high capacitance value of 440 F g?1 was obtained at a scan rate of 5 mV s?1 in a 3-electrode method. Apart from high capacitance value, the prepared electrode depicted 94% initial capacitance retention value after 2000 charge-discharge cycles at a current density of 8 A g?1. The fabricated symmetrical supercapacitor depicted a high energy density of 12.6 Wh kg?1 and a high power density of 4003 W kg?1. This was attributed to the better electrical conductivity of NiCo2O4 nanorods. © 2018 Elsevier B.V.