Two dimensional Janus SGaInSe(SeGaInS)/PtSe2 van der Waals heterostructures for optoelectronic and photocatalytic water splitting applications

Hydrogen generation by photocatalytic water splitting is considered as a viable and clean energy source for dealing with energy shortages and environmental pollution challenges. By means of first-principles calculations, the SGaInSe(SeGaInS)/PtSe2 van der Waals (vdWs) heterostructures are confirmed to be energetically, dynamically, and thermally stable, indicating that they have a lot of potential for experimental implementation. The Model-I of SGaInSe/PtSe2 heterostructures possesses type-II indirect band alignment, while the other three heterostructures retain type-I band alignment, which is further tuned to type-II with the application of strain. The charge transfer to SGaInSe/SeGaInS layer from PtSe2 layer generates built-in electric field that effectively resists the recombination of photo-generated electron-hole pairs. At pH = 0, the band edge positions of both heterostructures completely straddle the redox potentials. The Model-I of SeGaInS/PtSe2 heterostructures with biaxial −2% compressive strain makes the band edges to do complete water splitting in natural environment (pH = 7). In the visible range of the irradiating spectrum, our designed heterostructures have enhanced imaginary part of the dielectric function and absorption coefficient up to 105 cm−1. Moreover, with the biaxial compressive (tensile) strains, the blue-shift (red-shift) in absorption spectra is examined. Our study extends the applications of Janus monochalcogenides/PtSe2 vdWs heterostructures and supports to design of more heterostructures-based photocatalysts and optoelectronic devices.