J-J Shim, T.T. Nguyen, C. Lamiel
Keywords: graphene, metal oxide, nanocomposite, supercapacitor, energy storage
Summary:Graphene/metal oxide nanocomposites have been developed for energy storage applications such as supercapacitors. Electrochemical performance of the nanocomposites has been improved due to the synergistic effect of excellent conductivities and mechanical properties of graphene sheets and the high pseudocapacitance of metal oxides. Most metal oxides are low costs and doping of graphene with metal oxide nanoparticles enhances the energy density remarkably, resulting in an excellent performance as an electrode material for supercapacitors. Various methods have been developed to fabricate graphene/metal oxide nanocomposites. During the process of this materials, however, a large amount of harmful organic solvents have been normally required. To solve this problem, “green” solvents such as supercritical carbon dioxide, ionic liquids, and water have been used as an alternative to the organic solvents in the development of advanced materials. In this study, a series of graphene/metal oxide nanocomposites were prepared by hydrothermal method using green solvents. Metal oxide nanostructures with different morphologies have been distributed to the surface of graphene sheets well. The resulting nanocomposites have high surface area, high conductivity and a significant improvement in their electrochemical properties. The as-prepared materials exhibited outstanding electrochemical performance with very high specific capacitances and cycling stabilities for high performance supercapacitors. These “green” routes can also be applied to other materials.