Direct Z-scheme GaTe/SnS2 van der Waals heterojunction with tunable electronic properties: A promising highly efficient photocatalyst

Abstract

The production of hydrogen through photocatalytic water splitting offers a secure and eco-friendly approach. In this study, the application of GaTe/SnS2 heterojunction in the field of photocatalysis was studied in depth by using the first-principles calculation method. Based on single-layer GaTe and SnS2, a novel two-dimensional GaTe/SnS2 van der Waals heterojunction (vdwH) was constructed. Through analytical calculations, it is obvious that the GaTe/SnS2 heterojunction has an indirect bandgap of 0.85eV. Furthermore, its type-II band alignment facilitates efficient separation of photogenerated electrons and holes across different layers. The application of Bader charge analysis revealed an intriguing observation: the GaTe layer transferred a charge of 0.058e to the SnS2 layer. This charge transfer led to the creation of a robust built-in electric field, which played a pivotal role in efficiently inhibiting the recombination of photogenerated electrons and holes. Under the condition of pH = 0, GaTe/SnS2 heterojunction can promote redox reaction and realize water splitting. In addition, when the biaxial strain of -3%–3 % is applied to the GaTe/SnS2 heterojunction, the band edge position and light absorption properties are effectively changed, and more photons participate in the water splitting process. More importantly, the solar-to-hydrogen (STH) efficiency of GaTe/SnS2 heterojunction reaches 56.6 %, and when ε = 3 %, ηSTH increases to 58.21 %. Hence, our research showcases the GaTe/SnS2 heterojunction's potential as a highly efficient Z-scheme photocatalyst for water splitting, offering promising prospects for hydrogen production.