Effect of thermal reduction temperature on the electrochemical performance of reduced graphene oxide/MnO2 composites

Thermally reduced graphene oxide (RGO)/MnO2 composites were prepared by the thermal reduction of graphene oxide (GO)/MnO2 composites. The structure, electrical conductivity and specific capacitance of the composites before and after thermal reduction were investigated by SEM, XRD, FT-IR, the four-point probe method and cyclic voltammetry. Results showed that the GO and RGO significantly decreased the agglomeration of MnO2. The RGO/MnO2 composites had higher specific capacitances than pure MnO2 or GO/MnO2 composites. A RGO/MnO2 composite reduced at 600 °C had the highest specific capacitance of 321Fg−1 and good stability upon cycling. The presence of an optimum reduction temperature could be accounted for by the fact that the thermal reduction decreased the amount of oxygen-containing functional groups that contribute to pseudocapacitance in GO and increased its electrical conductivity which favors a capacitance increase.