Two-dimensional heterostructures of AuSe/SnS for the photocatalytic hydrogen evolution reaction with a Z-scheme

Two-dimensional (2D) heterostructures with the Z-scheme can significantly improve the recombination of the photogenerated charge pairs and increase the overpotential compared with the corresponding monolayers. Based on first-principles calculations, we demonstrate the photocatalytic performance with the Z-scheme of three 2D AuSe/SnS heterostructures identified from nine stacking types of AuSe and SnS monolayers using their formation energies. The thermal stabilities of the chosen heterostructures are assured by molecular dynamics simulations. The band alignment and built-in electric field support the heterostructures to drive the photocatalytic hydrogen and oxidation evolution reactions with the direct Z-scheme. Moreover, the optical absorption of both AuSe and SnS monolayers is obviously observed in the visible light and UV ranges, indicating their excellent response to solar light. The highest solar-to-hydrogen energy conversion efficiency of the heterostructures can reach 23.96%. The change in Gibbs free energy in the hydrogen evolution reaction with the heterostructures is in the range of 0.63–0.97 eV, indicating that these reactions are not difficult to carry out. Therefore, the present AuSe/SnS heterostructures could be promising candidates for producing hydrogen from photocatalytic water splitting with the Z-scheme driven by solar light.