First‐Principles Study on Electronic and Optical Properties of Novel Potential Photocatalytic Water‐Splitting Material: Blue‐P/Hf2CO2 vdW Heterostructure

ABSTRACT In this work, we set a series of blue‐P/Hf2CO2 vdW heterostructures by stacking blue‐P and Hf2CO2 monolayers together. Then the most stable structure, the AD‐stacking blue‐P/Hf2CO2 vdW structure (the HS), is selected out for further investigation. The electronic and optical properties of the HS are studied for exploring its potential applications. Result of its electronic structure investigation indicates that the HS is a type‐I band arrangement. By applying different biaxial strains parallel to the stacking direction to the HS, we regulate its band gap and band edge positions. Results show a suitable strain not only can adjust the band alignment type of the HS change from type‐I to type‐II but also regulate the band structure to a suitable band edge positions for photocatalytic water splitting. The band edge position of HS (2%) across the oxidation and reduction potential indicates that it is a potential photocatalyst of water splitting at pH = 7. By calculating the absorption coefficient, we found the HS (2%) has a good light‐harvesting ability in visible light and UV region, which further proves it has the potential as the sunlight‐driven photocatalyst for water splitting. A large difference in the electrostatic potential between blue‐P and Hf2CO2 monolayer leads to an built‐in electric field establishing at the HS (2%) interface. For HS (2%), its CBM is higher than −4.07 eV and VBM is lower than −5.30 eV, making it a potential photocatalysts of water splitting at pH = 7. (a) Planar average electrostatic potential; (b) the band alignment of HS (2%).