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.