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

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.