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-pointprobe 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 ℃ had the highest specific capacitance of 321 F·g^-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.