Low-temperature synthesis of sea urchin-like Co-Ni oxide on graphene oxide for supercapacitor electrodes

Abstract Transition metal oxides are ideal electrode materials used for supercapacitors. However, the synthesis of transition metal oxides suffers from drawbacks such as high reaction temperature and energy consumption. Herein, we report the synthesis of sea urchin-like Co3O4-NiO composites supported on graphene oxide (GO) using a hydrothermal method followed by calcination with a low temperature (250 °C). The obtained Co3O4-NiO/GO composite demonstrates a high specific capacitance of 883 F g−1 at 1 A g−1. Furthermore, upon coupling with an activated carbon (AC) positive electrode, an asymmetric cell of Co3O4-NiO/GO//AC exhibits outstanding stability reflected by the high capacitance retention of 82% at a high current density of 10 A g−1. The excellent electrochemical properties of the composite may be attributed to the good synergistic effect of Co3O4 and NiO, as well as the assembly of Co3O4 and NiO into a sea urchin structure, which results in increased electron conductivity and more exposed electroactive sites leading to the promotion of the Faradaic redox process.