▎ 摘　　要

Density functional theory calculations were performed to study the photocatalytic properties of molybdenum disulfide/graphene composites by analyzing the structure, electronic properties and optical properties of molybdenum disulfide/graphene composites. Three typical structures of molybdenum disulfide considered in our work include pristine molybdenum disulfide and molybdenum disulfide with mononiobium doping. They were then composited with graphene, N-doped graphene and graphene with epoxy, respectively. The characteristics of these composites (MoS2/graphene, MoS2/N-G, MoS2/O-G and Nb-MoS2/N-G) including binding energies, charge transfer, projected density of states, electron density and optical properties were calculated and analyzed. The binding energies of between MoS2 and graphene were related to the extent of charge transfer. The data of projected density of states, band structures and optical properties gave an explanation of the mechanism for significant photocatalytic activity of MoS2/N-doped graphene and Nb-doped MoS2/N-doped graphene composites. (C) 2015 Elsevier B.V. All rights reserved.