First-principles study on the type-II g-C6N6/GaS heterojunction: A promising photocatalyst for water splitting

The electronic transport properties, photocatalytic reaction mechanism and optical properties of novel g-C6N6/GaS heterojunction are investigated by first-principles calculations in this work. The results demonstrate that gC(6)N(6)/GaS forms a type-II heterojunction with the band edge straddling the redox levels of water and satisfying the requirements for overall water splitting reactions. Driven by the band offset and the built-in electric field at the interface, the photogenerated electrons and holes flow to the conduction band of g-C6N6 and the valence band of GaS, respectively. The effective separation of electron-hole pairs in space benefits to improve the photocatalytic efficiency. In addition, g-C6N6/GaS heterojunction exhibits excellent optical absorption in visible light region. Therefore, the g-C6N6/GaS heterojunction is a promising candidate for photocatalytic overall water splitting and solar energy conversion.