Graphene Anchored with NiO-MnO2 Nanocomposites for Use as an Electrode Material in Supercapacitors

Abstract

Graphene/NiO-MnO2 nanocomposite was formed by a simple chemical precipitation method using a chelating agent and Ni and Mn hydroxides on graphene. The graphene/NiO-MnO2 was pretreated by ultrasonication followed by thermal annealing at 300°C for 2 h. The capacitive behavior of the graphene/NiO-MnO2 electrode was investigated by cyclic voltammetry and galvanostatic charge/ discharge methods in a 6 M KOH aqueous solution. The maximum specific capacitance of the graphene/NiO-MnO2 electrode was 242.15 F g−1 by cyclic voltammetry at a scan rate of 0.2 mV s−1, which was significantly higher than that of a graphene electrode. Both the graphene and graphene/NiO-MnO2 electrodes exhibited capacitive behaviors and the NiO-MnO2 nanoparticles increased the capacitance of the supercapacitor.