2D SnO/MoO3 van der Waals heterojunction with tunable electronic behavior for multifunctional applications: DFT calculations

• 2D SnO/MoO 3 vdW heterojunction was constructed through first-principles calculations. • Two layers in 2D SnO/MoO 3 are not restricted by the horizontal displacement. • Z-scheme 2D SnO/MoO 3 showed remarkable photocatalytic CO 2 reduction ability. • The main products of CO 2 reduction on 2D SnO/MoO 3 are CH 4 and CH 3 OH. • Band alignment of 2D SnO/MoO 3 can be effectively adjusted by negative electric field. Metal oxide van der Waals (vdW) heterostructures have attracted extensive attention in fundamental research and new-device design. The remarkable advantage of their tunable energy band structure makes it particularly important to develop versatile metal-oxide heterojunctions and to explore their mechanisms. Herein, 2D SnO/MoO 3 vdW heterojunction is successfully constructed by first-principles calculations. Interestingly, the two layers are not limited by horizontal displacements when forming the heterojunction. The electronic structure of the SnO/MoO 3 vdW heterojunction has been systematically investigated, and the underlying physical mechanism responsible for its band alignment has been further revealed. A Z-scheme charge transfer mechanism has been demonstrated in SnO/MoO 3 with remarkable photocatalytic CO 2 reduction capability. Most importantly, the band alignment can be efficiently tuned by varying the external electric field, indicating its multifunctional potential. Furthermore, the CO 2 reduction reaction pathway and product selectivity occurring at the surface of 2D SnO/MoO 3 vdW heterojunction can be optimized by adjusting the applied electric field. These findings will provide strong theoretical support for the design of novel multifunctional devices using SnO/MoO 3 vdW heterojunctions.