ScSeI Monolayer for Photocatalytic Water Splitting.

We theoretically identify the ScSeI monolayer as a promising new 2D material for photocatalysis through first-principles calculations. The most notable feature is the significant difference in carrier mobility, with electron mobility in the horizontal direction being 20.66 times higher than hole mobility, minimizing electron-hole recombination. The ScSeI monolayer exhibits a bandgap of 2.51 eV, with the valence band maximum at -6.37 eV and the conduction band minimum at -3.86 eV, meeting the requirements for water splitting. Phosphorus doping lowers the Gibbs free energy by 1.63 eV, enhancing the catalytic activity. The ScSeI monolayer achieves a hydrogen production efficiency of 17%, surpassing the commercial threshold of 10% and shows excellent mechanical, thermal, and dynamic stability, indicating feasibility for experimental synthesis and practical application. Additionally, the monolayer maintains its photocatalytic properties under tensile strain (-6% to 6%) and in aqueous environments, reinforcing its potential as an effective photocatalyst. Based on these findings, we believe the ScSeI monolayer is a highly promising photocatalyst.