PtTe2/Sb2S3 Nanoscale Heterostructures for the Photocatalytic Direct Z-Scheme with High Solar-to-Hydrogen Efficiency: A Theoretical Investigation

We find that the PtTe2/Sb2S3 nanoscale heterostructure can drive the direct Z-schemes with high solar-to-hydrogen efficiency (STHE), although the band alignments of the PtTe2 and Sb2S3 monolayers turn out not to meet the redox potential conditions for the photocatalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), according to the band edges projected on each monolayer of the heterostructure and the built-in electric fields. The results indicate that the maximum STHE of the PtTe2/Sb2S3 nanoscale heterostructure can reach 28.82% and reveal that the compressive strain can remarkably decrease the STHE, although the tensile ones have no insignificant influence. Therefore, the compressive strains should be avoided in experimental preparations to achieve higher STHE. The thermodynamic feasibilities of HER and OER are confirmed by the Gibbs free energies in the reactions. Based on the preferable adsorbed sites for the intermediate products by screening calculations, the maximum ΔGH* for HERs is 1.396 eV and those for the rate-determining steps of OERs can be reduced to 2.089 eV by the dual-site process. All findings indicate that the present PtTe2/Sb2S3 nanoscale heterostructure is a promising candidate for driving overall water splitting for hydrogen generation.