Blue Phosphorus/Mg(OH) 2 van der Waals Heterostructures as Promising Visible-Light Photocatalysts for Water Splitting

To construct efficient solar-driven devices, considerable efforts have been made to search for desirable photocatalysts for water splitting. Motivated by recent successful syntheses of single-layer blue phosphorus (BlueP) and Mg(OH) 2, we systematically investigate the stability, energy band structure, charge transfer, and potential photocatalytic properties of the BlueP/Mg(OH) 2 van der Waals heterostructure using the first-principles method. It is found that all the heterostructures considered possess similar electronic and optical properties and exhibit type-II band alignment and indirect band gap characteristics. In addition, the ground-state configuration (β-stacking) of the heterostructure is found to be a potential photocatalyst for water splitting. In particular, its band gap, band-edge positions, and optical absorption can be tuned by in-layer biaxial strain to improve the efficiency of the photocatalytic water splitting. Our findings provide a new possibility of designing efficient photocatalysts for water splitting.