The charge transfer feature and high photocatalytic activity of S-scheme TiO2/h-BN heterostructure from first-principles

Designing compound photocatalyst with heterostructure is generally supposed to be a pragmatic strategy to attain effective charge separation and improve solar-driven water splitting. In this work, the photogenerated carrier transfer and photocatalytic properties of TiO2/h-BN heterostructure are systematically explored by density functional theory (DFT) calculations. The calculations indicate that a stable heterojunction structure is composed of TiO2 (1 0 0) surface and h-BN monolayer. According to the analysis of electronic structure and nonadiabatic molecular dynamics (NAMD), TiO2/h-BN heterostructure can be classified as S-scheme photocatalyst with strong redox ability. The strong interlayer interaction, built-in electric field and band bending can be formed by the construction of heterostructure, which will bring about recombination (separation) of electron-hole pairs with weak (strong) redox ability at the interface. Both HER and OER process of water splitting can be carried out spontaneously by TiO2/h-BN heterostructure under light irradiation and different pH values. Besides, the band gap and type of TiO2/h-BN heterostructure are almost unchanged under the action of biaxial strain, which illustrates that TiO2/h-BN heterostructure possesses strain resistance. Therefore, the present works not only discover a potential S-scheme photocatalyst for water splitting, but also offer a way to develop high-performance photocatalysts.