Visible‐Light‐Driven Spontaneous Water Splitting in a 2D Janus WSSe/GaO Z‐Scheme Heterostructure

Solar‐driven photocatalytic water splitting is a pivotal technology for global carbon neutrality, with the core challenge being the development of efficient, stable photocatalysts operating without sacrificial agents. Two‐dimensional (2D) Z‐scheme heterostructures are promising for efficient charge separation, while Janus materials with intrinsic polarization offer unique opportunities to enhance photocatalytic performance. Herein, we systematically investigate a 2D Janus WSSe/GaO heterostructure constructed from Janus WSSe and GaO monolayers via first‐principles calculations. The results demonstrate that the heterostructure exhibits a high electron mobility of 1864.53 cm 2 V −1 s −1 and broadband visible‐light absorption. Owing to its Z‐scheme band alignment, the heterostructure enables spontaneous water‐splitting hydrogen production under neutral or acidic conditions, achieving a theoretical solar‐to‐hydrogen conversion efficiency of 20.99%—surpassing most reported 2D heterostructures. This work highlights the potential of Janus‐based Z‐scheme heterostructures for high‐performance photocatalysis and provides a theoretical basis for experimental fabrication.