Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
13 results
Search Results
Item 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.Item Fabrication and performance evaluation of hybrid supercapacitor electrodes based on carbon nanotubes and sputtered TiO2(Institute of Physics Publishing michael.roberts@iop.org, 2016) Aravinda, L.S.; Nagaraja, K.K.; Nagaraja, H.S.; Bhat, K.U.; Badekai Ramachandra, B.R.We report a simple and eco-friendly method for the fabrication of a titanium dioxide/functionalized multiwalled carbon nanotube (TiO2/FMWCNT) composite electrode for use in supercapacitors. The nanocomposite electrodes were formed by depositing titanium dioxide onto FMWCNTs using reactive magnetron sputtering, thus providing a green roue for the formation of the binder-free composite electrode. It is shown that the electrochemical performance of the fabricated electrodes can be altered by tuning the thickness of the titanium dioxide overlayer. The integrated nanocomposite electrode showed an improved specific capacitance of 90 Fg-1 in two-electrode configuration. © 2016 IOP Publishing Ltd.Item 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.Item Hydrothermally synthesized reduced graphene oxide and Sn doped manganese dioxide nanocomposites for supercapacitors and dopamine sensors(Elsevier Ltd, 2017) Shanbhag, D.; Bindu, K.; Aarathy, A.R.; Ramesh, R.; Moolayadukkam, M.; Nagaraja, H.S.?-MnO2 nanowires and its nanocomposites (rGO-MnO2 and Sn@rGO-MnO2) were synthesized by a facile hydrothermal technique. Two important electrochemical applications of nanocomposites, viz, electrodes for supercapacitor and sensors for a biomolecule, dopamine are reported. The prepared nanowires have been characterized by XRD, which reveals smaller crystallite size of rGO- MnO2 composites compared to pristine MnO2 and the trend is supported by BET analysis. The wrapping of MnO2 NWs with rGO sheets increases the surface area, as well as, creates more dislocations at the interfaces. The correlation between physicochemical properties leads to an enhancement in the electrochemical performance of the materials. The as-fabricated Sn@rGO-MnO2 supercapacitor electrode reveals superior performance. The specific capacitance of 139.05, 309.7 and 460.9 F/g at a scanning rate of 20 mV/s, in an aqueous Na2SO4 solution (1 M) is obtained for MnO2, rGO-MnO2 and Sn@rGO-MnO2 respectively. Also, the reported nanocomposites show excellent performance towards detection of dopamine. Among ?-MnO2/GCE, rGO-MnO2/GCE and Sn@rGO-MnO2/GCE based sensors for Dopamine detection, rGO-MnO2/GCE sensor exhibits the highest sensitivity of 433.6 ?A/mM and broad linear range, whereas Sn@rGO-MnO2 exhibits lower detection limit of 0.13 ?M. © 2017 Elsevier LtdItem Chemically prepared Polypyrrole/ZnWO 4 nanocomposite electrodes for electrocatalytic water splitting(Elsevier Ltd, 2019) Brijesh, K.; Bindu, K.; Shanbhag, D.; Nagaraja, H.S.ZnWO 4 , PPy, and PPy/ZnWO 4 nanoparticles were prepared using chemical synthesis. The structural, compositional and morphological properties of the prepared samples have been investigated using XRD, FTIR, SEM, and HRTEM respectively. The powder XRD reveals the monoclinic wolframite structure for both ZnWO 4 and PPy/ZnWO 4 nanocomposite. SEM confirms the wrapping of ZnWO 4 with PPy. The electrodes of ZnWO 4 , PPy, and PPy/ZnWO 4 have been tested as bifunctional electrocatalyst towards HER and OER using constant current chronopotentiometry (CP) and Linear Sweep Voltammetry (LSV). The electrochemical surface area and the electrocatalytic activity PPy/ZnWO 4 nanocomposite towards HER and OER are greater than that of pure ZnWO 4 and PPy. The Tafel slope of PPy/ZnWO 4 nanocomposite is 76 and 84 mV dec ?1 in 0.5 M H 2 SO 4 and 1 M KOH at room temperature for HER and OER respectively. The results suggest that PPy/ZnWO 4 nanocomposite is a good candidate for the bifunctional electrocatalyst for water splitting. © 2018 Hydrogen Energy Publications LLCItem 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 Dual electrochemical application of r-GO wrapped ZnWO4/Sb nanocomposite(Institute of Physics Publishing helen.craven@iop.org, 2019) Brijesh, K.; Bindu, K.; Amudha, A.; Nagaraja, H.S.ZnWO4/Sb nanorods and r-GO-ZnWO4/Sb nanocomposite have been prepared using a single step solvothermal method. The prepared nanocomposites have been characterized using x-ray diffractometer (XRD), Scanning Electron Microscope (SEM), High Resolution Transmission Electron Microscope (HR-TEM), Raman and Brunauer-Emmett-Teller (BET). The x-ray photoelectron spectroscopy (XPS) technique was used to determine the elemental composition of ZWS-5 (5 mg r-GO-ZnWO4/Sb) composite. The XRD reveals the monoclinic wolframite structure of ZnWO4/Sb and r-GO-ZnWO4/Sb. SEM and HRTEM confirms that the ZnWO4/Sb has been decorated on the r-GO sheets. The electrochemical performance of the prepared samples towards the Hydrogen Evolution Reaction (HER) and dopamine sensing has been tested using electrochemical techniques. Onset potential of 265 mV @10 mA cm-2, lower Tafel slope (95 mV dec-1), high electrochemical surface area (1383.216 m2g-1) and high specific site density (18.551 06 × 1021 g-1) of ZWS-5 reveals the high electrocatalytic activity of the composite towards HER. Chronoamperometric dopamine sensing shows that ZWS-5 has the superior sensing performance with highest specific sensitivity (723 ?A ?M-1 ?g-1), lowest limit of detection (0.9624 ?M), along with a good selectivity. Results suggest that the r-GO-ZnWO4/Sb nanocomposite is a good candidate for the HER and electrochemical dopamine sensor. The incorporation of r-GO nanosheets with ZnWO4/Sb (ZWS) nanorods enhances the specific and electrochemical surface area, which accounts for the high electrocatalytic activity of the composite. © 2019 IOP Publishing Ltd.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 Ltd