Polarization Switching of Photocatalytic Solar-to-Hydrogen Conversion in Two-Dimensional Single-Layer Lattices: Insights from First-Principles and Non-adiabatic Molecular Dynamics.

Two-dimensional polar materials with adjustable polarization hold significant potential to improve photocatalytic water-splitting performance. However, due to the distinct mechanism for regulating polarization and photocatalysis, achieving efficient polarization modulation for enhanced photocatalytic efficiency remains challenging. Herein, using first-principles calculations with non-adiabatic molecular dynamics simulations, we identify four single-layer materials of MoXX'N₃Y (X and X' = Si and Ge; X ≠ X'; and Y = P and As), whose catalytic activity can be well-tuned by polarization switching. Adjusting electronic asymmetry contributes to effective control of electric polarization, ultimately affecting catalytic reaction paths and carrier dynamics. Consequently, P↑ MoGeSiN₃Y allows spontaneous redox reactions for overall water splitting, unlike P↓ MoSiGeN₃Y. Besides, the polarization switching in MoXX'N₃Y monolayers enhances solar-to-hydrogen conversion efficiency and prolongs carrier lifetimes, thereby achieving a polarization-dependent photocatalytic switch. This study opens an avenue to modify the polarization and significantly improve the catalytic efficiency.