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

Abstract

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.