Construction of CdS/SnSSe heterostructures for direct Z-scheme photocatalysis: a first-principles computational study

Abstract The construction of van der Waals (vdW) heterojunctions (HJs) offers an important means to enhance the properties and expand the applications of two-dimensional (2D) materials. The CdS/SnSSe HJs, comprising CdS/SSnSe and CdS/SeSnS HJs, have been designed and investigated as potential water-splitting photocatalysts using hybrid density functional theory. The suitable interface formation energies and interlayer distances confirm that both CdS/SSnSe and CdS/SeSnS HJs are vdW HJs. The small bandgaps allow CdS/SSnSe and CdS/SeSnS HJs to absorb adequate solar light. Based on the analysis of work functions, charge transfer, and band edge positions, the direct Z-scheme photocatalytic mechanism for CdS/SSnSe and CdS/SeSnS HJs is validated. This mechanism is beneficial for achieving spatial separation of photoexcited carriers and maintaining sufficient redox reaction driving potentials. All these results demonstrate that both CdS/SSnSe and CdS/SeSnS HJs are promising candidates as water-splitting photocatalysts.