The synergistic enhancement of photocatalytic hydrogen evolution performance and electrical conductivity in XS2(X=Sn,Pt)/Ga2SSe vdW heterostructures based on first-principles

Photocatalytic hydrogen production technology has attracted significant attention due to its clean and sustainable characteristics. However, conventional single-component photocatalysts commonly suffer from rapid recombination of photogenerated electrons and holes, which severely limits their photocatalytic performance. To address this critical issue, this study innovatively constructs an XS 2 (X = Sn,Pt)/Ga 2 SSe van der Waals heterostructure system. The two heterostructures were systematically studied via first-principles calculations for their stability, electronic and optical properties, and photocatalytic mechanisms. Results show both heterostructures exhibit excellent stability and unique band alignments, with the valence band maximum (VBM) and conduction band minimum (CBM) mainly governed by Ga 2 SSe and SnS 2 (PtS 2 ), respectively. Their band positions fully satisfy the redox potential requirements for water splitting. Compared to their monolayers, both heterostructures show enhanced electrical conductivity, which promotes carrier separation and boosts solar-to-hydrogen conversion efficiency, achieving high hydrogen evolution efficiencies of 31.95 % and 17.41 %, respectively, under AM1.5G illumination-demonstrating a synergistic enhancement of photocatalytic performance and conductivity. They also exhibit superior light absorption and higher refractive indices. Gibbs free energy calculations confirm excellent the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) activity, with optoelectronic properties further tunable via biaxial strain. • XS 2 (X = Sn,Pt)/Ga 2 SSe heterostructures show synergy for H 2 evolution and conductivity. • Band edges straddle water redox potentials across the full pH range. • Solar-to-hydrogen efficiencies reach up to 31.95 % and 17.41 %. • Biaxial strain enhances optical properties and electrical conductivity.