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.