Conjugated NiO‐ZnO/GO nanocomposite powder for applications in supercapacitor electrodes material

Abstract

The nanocomposite of NiO-ZnO/graphene oxide (GO) was synthesized for applications in supercapacitor electrodes material. GO was produced using the modified Hummers' method, and the nanocomposite of NiO-ZnO/GO was synthesized using the co-precipitation method. Thin films of nanocomposite powder were deposited on quartzite (glass) and fluorine-doped tin oxide substrates by a drop casting technique. X-ray diffraction revealed the crystallographic information of NiO-ZnO/GO nanocomposites. The surface morphology and elemental composition were studied using a scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. The electrochemical properties were examined using cyclic voltammetry in a 1.0 M solution of Na2SO4 electrolyte with a three-electrode system. Moreover, the NiO-ZnO/GO binary metal oxides nanocomposite based electrodes fabricated for supercapacitor delivered a high specific capacitance of 1690 F g−1 for 1:1/GO sample at a scan rate of 10 mV s−1 and has excellent conductivity due to reduced band gap energy range of 1.52-1.79 eV and with electrodes resistance of 0.02 Ω. The absence of semicircle in the Nyquist plot denotes low charge transfer resistance of the electrodes. The highest energy densities obtained for 1:1/GO and 2:1/GO are 192 and 148 Wh kg−1, respectively, while the highest power density obtained for 1:1/GO and 2:1/GO are 8.46 and 7.42 W kg−1, respectively. Our study paves way for a facile, affordable, nontoxic, and fast way to synthesis binary transition metal oxides/GO-based electrodes material for high-performance supercapacitor.