Synthesis of Co3O4/reduced graphene oxide by one step-hydrothermal and calcination method for high-performance supercapacitors

Abstract

In this work, a simple and environmental one step-hydrothermal and calcination method was used to prepare Co3O4/reduced graphene oxide (rGO) composite. The result shows that tiny Co3O4 nanoparticles are dispersed on rGO sheets to form a three-dimensional structure, which provides more active sites than Co3O4 nanowires structure. When acting as an electrochemical supercapacitor, structure optimized Co3O4/rGO-120-12 electrode exhibits high specific capacitance of 1152 F/g at 1 A/g in 6 M KOH electrolyte. As an assemble device, Co3O4/rGO reveals higher specific capacitance (about 85 F/g) than Co3O4 (about 36 F/g) at current density of 1 A/g and excellent stability with 89.1% after 5000 cycles. The device exhibits a relatively high energy density of 57.26 Wh/kg at a power density of 2240.68 W/kg. Hence, the superior pseudocapacitive performance of Co3O4/rGO can be ascribed to the synergy between rGO and Co3O4 as well as the excellent three-dimensional structure obtained by changing the hydrothermal conditions.