Synthesis and electrochemical performance of Co3O4/graphene

Co3O4/reduced graphene oxide composites were synthesized via a simple electrochemical method from graphene oxide and Co(NO3)2·6H2O as raw materials. Co3O4 nanoparticles with sizes of around 30–50 nm were distributed on the surface of graphene nanosheets confirmed by scanning electron microscopy and transmission electron microscopy. Electrochemical properties of Co3O4/graphene composite were tested by cyclic voltammetry, galvano-static charge-discharge, and electrochemical impedance spectroscopy. The Co3O4/reduced graphene oxide composite was used as the pseudocapacitor electrode in the 2 mol/L NaOH aqueous electrolyte solution. The Co3O4/reduced graphene oxide composite electrode exhibited a specific capacitance of 357 F/g at a current density of 0.5 A/g in a three-electrode system. 72% of capacitance was retained when the current density increased to 3 A/g. The Co3O4/reduced graphene oxide composite prepared electrodes show a high rate capability and excellent long-term stability. After 1000 cycles of charge and discharge, the capacitance is still maintained 87% at a current density of 1 A/g, indicating that the composite is a promising alternative electrode material used for supercapacitors.