Polydopamine-assisted formation of Co3O4-nanocube-anchored reduced graphene oxide composite for high-performance supercapacitors

Tailoring transition-metal oxide nanoparticles with two-dimensional carbon has become a favorite way to improve their electrochemical performance. In this study, a composite of reduced graphene oxide was anchored by Co3O4 nanocubes and easily prepared with the assistance of polydopamine (PDA), using a combination of hydrothermal reaction and pyrolysis (Co3O4@PDA-rGO). Polydopamine, which possesses abundant catechol and amine groups, could be easily grafted onto graphene oxide to reduce the aggregation of graphene particles. Furthermore, PDA provided active sites, i.e., catechol and amine groups, which coordinated with Co2+, enabling enrichment of metal ions on the surface of graphene. After the pyrolysis of Co2+-containing PDA-grafted graphene at 400 degrees C, the Co2+ ions were converted into Co3O4 nanocubes, while the PDA carbonized to form N-doped porous carbon on the surface of graphene. The resulting product, Co3O4@PDA-rGO, demonstrated extraordinary supercapacitive behavior with good cycling stability owing to its unique porous structure as well as the intimate contact between Co3O4 and the carbon matrix.