Ternary Co3O4/NiO/reduced graphene oxide hybrid composites with improved electrochemical properties

Abstract

Abstract Transition metal oxides are considered to be ideal electrode materials for supercapacitors, but they usually suffer from poor conductivity and low capacitance. Herein, Co3O4 and NiO nanoparticles are decorated on reduced graphene oxide (rGO) to form ternary Co3O4/NiO/rGO composites using hydrothermal method. The study focuses on the dependence of the electrochemical properties on the molar ratio of cobalt to nickel, calcination temperature and rGO loading. Upon calcination at 400 °C, the Co3O4/NiO composites with a molar ratio of 1:3 display superior electrochemical performance. The adding of rGO to Co3O4/NiO composites can effectively enhance the dispersion of nanoparticles and improve the electrochemical performance overall. Compared with rGO and Co3O4/NiO, the high specific capacitance of 325 F/g at a current density of 0.5 A/g and good rate capability are achieved for ternary composites. The excellent electrochemical performance is probably attributed to the feature of cobalt and nickle oxides nanoparticles highly dispersed on rGO nanosheets. This can increase the electron conductivity, provide more exposed electroactive sites and facilitate the faradaic redox processes.