Mechanistic Study of CrS/BP as a Direct Z-Scheme Heterojunction for Photocatalyst of Splitting Water Under Biaxial Strain

Semiconductor photocatalysts are hampered by carriers' recombination problems that hinder their practical application. The rational design of direct Z-scheme heterojunctions based on two-dimensional (2D) materials is one of the effective ways to solve this problem. Therefore, we predicted 2D CrS/boron phosphide (BP) van der Waals heterojunction as a potential direct Z-scheme photocatalyst based on density functional theory. The CrS/BP heterojunction has a small direct band gap, which is favorable for light absorption. In addition, the built-in electric field promotes the separation and transfer of the desired carriers. Photogenerated electrons and holes are localized in the conduction band of the BP component and the valence band of the CrS component, respectively. In addition, it was found that the heterojunction obtained a relatively small band gap and a wide optical absorption range at + 4% and + 5% strains. Therefore, the CrS/BP heterojunction is a new photocatalyst satisfying the direct Z-scheme charge transfer mechanism, which has a certain application value. Graphical Abstract: [Figure not available: see fulltext.]