▎ 摘　　要

Graphene-BiFeO3 composites are synthesized through a one-pot hydrothermal method and their photocatalytic performances are investigated under visible light irradiation. Bandgap engineering of BiFeO3-graphene composites is achieved by simply adjusting the concentration of OH groups during the hydrothermal treatment. XPS and Raman analysis indicate that enhanced coupling between BiFeO3 nanoparticles and graphene is achieved by the formation of Fe-O-C bonds, which is mediated by OH groups adsorbed on the surface of graphene. The band gaps of the composites could be successfully tuned from 1.78 eV-2.24 eV, giving rise to high photocatalytic performance under visible light irradiation. This may be of significance in understanding the mechanism of the coupling between graphene and semiconductor oxides which are currently being intensively investigated as photocatalysts.