Synthesis of RGO–Co doped ZnO/PANI hybrid composite for supercapacitor application

Abstract

In this paper, reduced graphene oxide–cobalt doped ZnO/polyaniline (RGO–CZO/PANI) hybrid composites were synthesized through the two step approach: Cobalt doped ZnO particles on RGO sheets by a simple chemical co-precipitation method, followed by coating with PANI through in situ polymerization method. Morphological and structural properties were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Ultraviolet–Visible absorption spectra, scanning electron microscopy and transmission electron microscopy. Electrochemical performance of the RGO–CZO/PANI hybrid composites were carried out by cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy in 1M H2SO4 electrolyte medium. The findings show that the charge storage of RGO–CZO/PANI hybrid composite is mainly due to the pseudocapacitance (reversible redox reaction) behavior. The highest specific capacitance of 515 F g−1 with the energy density of 370 Wh kg−1 and power density of 3.1 kW kg−1 could be achieved (For three electrode system) in the potential region between −0.2 and 1.0. Notably, in a two-electrode system, the specific capacitance, energy density and power density of the RGO–CZO/PANI symmetric supercapacitor was obtained to be 208 F g−1, 28.88 Wh kg−1 and 0.694 kW kg−1, respectively. The results manifest that the synthesized RGO–CZO/PANI hybrid composite is the promising electrode material for supercapacitor applications.