Photoactivity and electronic properties of graphene-like materials and TiO2 composites using first-principles calculations

Graphene-like materials (GLM) have attracted intense attention in the research on photocatalytic technology due to their superior properties. First-principles calculations based on DFT were used to explore the photoactivity and electronic properties of graphene-like materials and TiO2 composites in this work. It was found that TiO2/GLM composites might be demonstrated for high thermodynamic stability. The electronic properties of TiO2/GLM, such as geometric structure, density of states, charge density, charge density difference and optical properties, were characterized. There were interactions between GLM sheets and TiO2, which caused charge accumulation on the GLM surface and charge depletion on the other side of TiO2 in the heterojunction. Electrons in the highest occupied molecular orbital (HOMO) consisted of the O2p orbital from TiO2 could be directly excited or dispersed to the lowest unoccupied molecular orbital (LUMO) composed of the hybridized orbital from GLM and TiO2 under irradiation. The produced well-separated electron-hole pairs induced an enhanced photocatalytic performance of TiO2/GLM. The theoretical results pointed out the electron migration and transfer path at the interface, which might illustrate the mechanism of enhanced photocatalytic activity of TiO2/GLM.