Photocatalytic water splitting performance of ScTeI monolayer with Janus structure: A first-principles study

Two-dimensional Janus materials have attracted significant attention in photocatalysis due to their unique layered structures and intrinsic electric fields. However, the recombination of photogenerated electrons and holes reduces charge utilization and limits performance, making the development of low-recombination materials a key challenge. This study investigates the ScTeI monolayer, a Janus material with an I-Sc-Te stacking sequence, using first-principles calculations. The results reveal significant anisotropy in carrier mobility: electron mobility is higher along the x-direction (2890.60 cm2V- 1s- 1), while hole mobility is higher along the y-direction (772.73 cm2V- 1s- 1). This anisotropy promotes carrier separation, reducing recombination and improving photocatalytic efficiency. Additionally, the Te site exhibits dual catalytic activity in both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), enhancing the effective use of photogenerated carriers. The ScTeI monolayer also demonstrates excellent thermodynamic and mechanical stability, with a binding energy of-3.79 eV/atom, indicating feasibility for experimental synthesis. It has a direct bandgap of 2.07 eV, meets the band edge requirements for water splitting, and shows strong visible light absorption. Theoretical calculations further indicate a solar-to-hydrogen efficiency (STH) of 23.66 %, significantly exceeding the 10 % threshold required for commercial applications. These findings underscore the ScTeI monolayer's potential in photo- catalytic water splitting and provide a solid theoretical foundation for designing high-performance photo- catalytic materials.