Interfacial Charge Transfer and Enhanced Photocatalytic Mechanisms for the Hybrid Graphene/Anatase TiO2(001) Nanocomposites

Abstract

In this paper, first-principle calculations based on density functional theory were carried out to explore the interface properties of the hybrid graphene/anatase TiO2 (001) nanocomposites (G/AT(001)N). The effect of graphene hybridization on energy gap, surface chemical bonding, interfacial charge transfer, and visible light response was investigated in detail. Because of the hybridization of graphene, the band structure of the G/AT(001)N was modified, and the energy gap was reduced to 0.47 eV. Electrons in the bottom of the valence band (VB) of anatase TiO2 could disperse to the upper part of the VB. And electrons in the upper part of the VB of anatase TiO2 were likely to be directly excited to graphene under visible light irradiation, which promoted the formation of well-separated electron–hole pairs. The interfacial electron transfer in the ground electronic state promoted electrons increased on graphene and substantial holes accumulated in TiO2(001) facet. Good linkage between TiO2(001) facet and graphene could facilitate the charge transfer, promoting photocatalytic efficiency improvement. Hybridization of graphene brought an obvious red shift in the absorption edge and enhanced absorption intensity in the visible region, which indicated the enhancement of photocatalytic performance. The calculation results illustrated the reported experimental observation [J. Phys. Chem. Lett. 2011, 2, 894–899] and would provide new insights into the design of graphene-based semiconductor photocatalysts.