Janus PtSSe-based van der Waals heterostructures for direct Z-scheme photocatalytic water splitting

The semiconductor photocatalysts based on van der Waals heterostructures (vdWHs) and direct Z-scheme mechanism are viable candidates for water splitting using sunlight. In this study, we exploit the combined effects of the inherent dipole in a Janus PtSSe monolayer and the intrinsic electric field present at the interface of Janus PtSSe-based vdWHs for water splitting. These vdWHs exhibit type-II band edge position, narrow band gap and intrinsic electric fields, establishing them as prototypical direct Z-scheme systems. Remarkably, the density functional theory-based results find the potential drop of similar to 0.2 - 3.2 eV across the interface of vdWHs, promoting the interlayer photogenerated carrier's recombination while suppressing the intralayer charge transfer, which leads to a direct Z-scheme charge transfer pathway with robust redox capabilities. In conjunction with redox reactions, the built-in electric field at the interface generates sufficient driving force for the photogenerated carrier's separation. Also, these Janus PtSSe-based vdWHs possess exceptional abilities in capturing visible light with high solar-to-hydrogen (STH) conversion efficiency. The results obtained from this study are important to designing efficient direct Z-scheme photocatalysts for splitting water under sunlight and offer valuable insights for potential commercial implementations.