Two-dimensional AuSe/SnSe heterostructure for solar photocatalytic hydrogen evolution reaction with Z-scheme

Abstract

The solar photocatalytic hydrogen evolution reaction (HER) with Z-scheme driven by the two-dimensional (2D) AuSe/SnSe heterostructure is explored. Three preferable geometrical configurations of the heterostructure are identified from nine structures stacked with the SnSe and AuSe monolayers by formation energies, and thermodynamic stability is confirmed by ab initio molecular dynamics simulation at 400 K. The projected band edges of the monolayers in the heterostructure, interlayer charge transfer, and built-in fields support the AuSe/SnSe heterostructure to drive the photocatalytic HER with the direct Z-scheme, which increases not only the overpotentials of the photocatalytic water decomposition to produce hydrogen, but also the optical absorptions. Thus, the maximum solar-to-hydrogen conversion efficiency could attain 32.95% if a suitable biaxial strain is applied. The effects of the interlayer distance on the geometrical structures and electronic properties are also examined, and the results show that the increase in distance is safe, but the decrease will damage the character of the vdW heterostructure. The changes of Gibbs free energies confirm that the HER with Z-scheme driven by the AuSe/SnSe heterostructure is feasible. These results could provide a theoretical guide for the development of photocatalysts for the efficient HER with the direct Z-scheme by using the AuSe/SnSe heterostructure.