GaN/BS van der Waals heterostructure: A direct Z-scheme photocatalyst for overall water splitting

Direct Z-scheme heterostructures have attracted much attention as promising solar-driven water splitting pho-tocatalysts. Here, the GaN/BS van der Waals heterostructures with Z-scheme charge transform model are con-structed. The electronic structure, optical properties and photocatalytic mechanism are investigated using the first-principles calculations. Our results demonstrate that the electrons migrate from GaN to BS layer in GaN/ BS heterostructure and its band edges straddle the water redox potentials, forming a direct Z-scheme photo -catalysts for overall water splitting. Biaxial and external electric field can effectively modulate the band edge positions and optical properties, promoting more photons participating in the water splitting. The solar-to -hydrogen efficiency eta STH of the heterostructure can reach 19.95 % at the epsilon = 6 %, significantly higher than GaN (0.28 %) and BS (1.55 %) monolayers. Negative electric field also can improve the eta STH. The work provides a valuable theoretical guidance for designing of the GaN/BS heterostructures and pointing that the hetero-structures have great promising for application in photocatalytic water splitting.