Optoelectronic properties and strain regulation of the 2D WS/ZnO van der Waals heterostructure.

The combination of zinc oxide (ZnO) and transition metal dichalcogenide (TMD) nanoparticles has higher photocatalytic efficiency and field emission performance than TMDs or ZnO, as well as significantly higher water cracking photocatalytic activity. By first-principles calculation, we investigated the structural and optoelectronic properties of the two-dimensional (2D) WS/ZnO van der Waals (vdWs) heterostructure, and the regulation effect of biaxial strain. It is revealed that the conduction-band minimum (CBM) is lower than the reduction potential of water (H ≈ -4.44 eV), and the valence-band maximum (VBM) is lower than the oxidation potential ( ≈ -5.67 eV), thus the heterostructure is a good oxidant in the water decomposition process, but cannot match the requirements for water reduction. By applying a -2% biaxial strain, the CBM is elevated to a position higher than the reduction potential of water, then the 2D vdWs WS/ZnO heterostructure becomes a good material for the application of water reduction and other photovoltaic and photocatalytic devices.