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 cm² 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.