Two-dimensional TMDs/MN (M = Al, Ga) van der Waals heterojunction photocatalyst: a first-principles study.

Finding efficient and environmentally friendly semiconductor photocatalysts can effectively alleviate the energy crisis and environmental pollution. Based on first-principles calculations, this work focused on the electronic, Bader charge and optical properties of the TMDs/MN heterojunctions. The results showed that the AlN/WS2 and GaN/WS2 heterojunctions are the type-II energy band arrangement, which indicates effective promotion of the separation of the photogenerated electron–hole pairs. Meanwhile, the AlN/WSe2, GaN/WSe2, AlN/MoSe2 and GaN/MoSe2 heterojunctions belonged to the type-I energy band arrangement. The Bader charge results showed that the built-in electric field formed by the heterojunction prevents the recombination of charge carriers. These type-I heterojunctions have excellent optical absorption ability and are suitable for optoelectronic components. Surprisingly, we found that the AlN/WSe2, GaN/WSe2, AlN/MoSe2 and GaN/MoSe2 heterojunctions transform type-I heterojunction to type-II heterojunction by applying electric field. This work further provides the theoretical basis for the design of efficient photocatalysts. [ABSTRACT FROM AUTHOR]