Rational design of a direct Z-scheme β-AsP/SiC van der Waals heterostructure as an efficient photocatalyst for overall water splitting under wide solar spectrum

Abstract

The solution to the issue of energy scarcity lies in the search for an effective photocatalyst. In this study, the monolayers β-AsP and SiC are selected to build a heterostructure as an efficient photocatalyst and its geometric structure and stability, electronic properties, interfacial charge transfer, band edge alignment, optical absorption and solar-to-hydrogen energy conversion efficiency, biaxial strain engineering for band gap and optical adsorption, and the driving force for photocatalytic water splitting are explored systematically using first-principles calculations. The results show that the β-AsP/SiC heterostructure is a semiconductor with a direct band gap of 1.65 eV, and the charge transfer path conforms to a direct Z-scheme mechanism, which can effectively suppress the recombination of photogenerated electron–hole and improve the catalytic efficiency. The β-AsP/SiC heterostructure possesses fascinating band edge position to induce water splitting. Moreover, the optical absorption of the heterostructure is better than that of its monolayer materials, and the solar-to-hydrogen efficiency can reach 5.9%. The effect of biaxial strain on the electronic structure and optical absorption properties is discussed. Furthermore, the analysis of Gibbs free energy confirms that the β-AsP/SiC heterostructure can spontaneously carry out the redox reaction of water splitting in an alkaline environment. Therefore, we believe that the β-AsP/SiC heterostructure provides an effective reference value for the development of efficient photocatalysts.