One-pot synthesis of graphene-molybdenum oxide hybrids and their application to supercapacitor electrodes

Abstract Electrochemical double-layer capacitor (EDLC) electrodes are conventionally based on carbon materials, which provide increased chemical stability and the possibility of a large number of charge and discharge cycles. However, their specific capacitance is generally much lower than pseudo-capacitors based on metal oxide or conductive polymer electrodes. Carbon-based electrodes for electrochemical devices can be hybridized with metal oxide functionalities in order to provide catalytic activity that increases their electrochemical performances. We report the preparation of a conductive hybrid electrode of reduced graphene oxide and molybdenum oxide by a facile one-pot hydrothermal synthesis. A three-dimensional network structure comprising graphene and molybdenum oxide was obtained when phosphomolybdic acid was used as a precursor for molybdenum oxide. The hybrid material contains polycrystalline nanoparticles of molybdenum (IV) oxide (MoO 2 ) that covers the surface of reduced graphene oxide. Compared to graphene electrodes, the hybrid electrodes showed significantly improved specific capacitance, as good as three times higher (381 vs. 140 F/g), and considerable reduction of the equivalent series resistance (by about half) when they were used in a supercapacitor with sodium containing aqueous electrolyte.