Electronic Structure and Charge Transfer in the TiO2 Rutile (110)/Graphene Composite Using Hybrid DFT Calculations

Abstract

Composite systems of TiO2 with nanocarbon materials, such as graphene, graphene oxide, and carbon nanotubes, have proven to be efficient photocatalyst materials. However, a detailed understanding of their electronic structure and the mechanisms of the charge transfer processes is still lacking. Here, we use hybrid density functional theory calculations to analyze the electronic properties of the ideal rutile (110)–graphene interface, in order to understand experimentally observed trends in photoinduced charge transfer. We show that the potential energy surface of pristine graphene physisorbed above rutile (110) is relatively flat, enabling many possible positions of graphene above the rutile (110) surface. We verify that tensile and compressive strain has a negligible effect on the electronic properties of graphene at low levels of strain. By analyzing the band structure of this composite material and the composition of the valence and conduction band edges, we show that both the highest occupied states a...