Feasibility study on theoretical design of Mo x W 1−x Se 2 /g-GaN heterojunction with type II band arrangement for photocatalytic water splitting

Photocatalytic water splitting offers a possible route to address energy and environmental problems, although electron-hole recombination limits the performance of single-component 2D transition metal dichalcogenide (TMDC) photocatalysts. Here, density functional theory (DFT) was used to construct MoxW1−xSe2/g-GaN by combining alloying with heterojunction formation. Alloying tunes the TMDC band gap, and the heterostructure exhibits a type II band arrangement. The interfacial built-in electric field favors Z-path carrier transfer, improves photogenerated-carrier separation, and extends the redox-potential range. These results support the potential application of MoxW1−xSe2/g-GaN in 2D TMDC-based photocatalysis.