Direct Z-scheme 2D/2D heterojunction of BP/monolayer SnSe2 with photocatalytic activities: A first-principles study

New high-efficiency photocatalysts are of great significance to solve the problems of environmental pollution and energy shortage in the world. In this paper, a Z-Scheme heterojunction of 2D/2D BP/SnSe2 heterojunction is designed, and its electronic structure and photocatalytic mechanism are systematically calculated based on first-principles calculations. The results show that BP/SnSe2 heterojunction is a direct band gap semiconductor with a band gap value of 0.69eV, and shows the intrinsic type-II staggered band alignment characteristics. A small band gap can accelerate the separation of photogenerated electrons and holes, and the built-in electric field makes the photogenerated electrons and holes transfer along the Z-scheme path, and the appropriate band edge position and high carrier mobility also show that BP/SnSe2 heterojunction is an excellent photocatalyst. In addition, the Gibbs free energy diagram also shows that BP/SnSe2 heterojunction can spontaneously complete water decomposition driven by solar energy. Finally, the effects of biaxial strain and pH value on the practical application were also studied. Therefore, we believe that BP/SnSe2 heterojunction can have a good application prospect as a new direct Z-scheme photocatalyst.