Dependence of photocatalytic activity on the direction of the intrinsic dipole in GaOI-based Janus structures

Abstract

In Janus photocatalysts, intrinsic dipole (P) plays an important role in the separation of photogenerated carriers and photocatalytic activity for water splitting. However, effectively switching the direction of the P vector between different surfaces is still an open issue. Based on first-principles calculation, we find that the P vector relies on charge distribution, while the distribution of the conduction band maximum-distributed reduction reaction surfaces (Sc) and valence band minimum-distributed oxidation surfaces (Sv) depends on the orbital hybridization in GaOI-based Janus. The direction of the P vector can be switched between Sc and Sv by substituting a metal or halogen atomic layer. The P vector in the direction from Sc to Sv releases bandgap limitation, broadens the light absorption range, and improves high carriers’ mobility and solar-to-hydrogen efficiency (STH) efficiency, while the P vector pointing from Sv to Sc hinders the photocatalytic activity of GaOI-based Janus. Based on the investigation of STH efficiency and redox reactions, GaInOI is found to be a potential photocatalyst for overall water splitting. The stability of the Janus is studied by ab initio molecular dynamics and phonon diffusion spectrum. Current work proposes that switching the direction of the P vector between Sv and Sc is a potential route to regulate the band structure, optical absorption, and photocatalytic activity in GaOI-based Janus.