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 (100) 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 photo catalyst 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.