Density Functional Theory Study on the Enhancement Mechanism of the Photocatalytic Properties of the g-CN/BiOBr(001) Heterostructure.

The van der Waals heterostructures fabricated in two semiconductors are currently attracting considerable attention in various research fields. Our study uses density functional theory calculations within the Heyd-Scuseria-Ernzerhof hybrid functional to analyze the geometric structure and electronic structure of the g-CN/BiOBr(001) heterojunction in order to gain a better understanding of its photocatalytic properties. The calculated band alignments show that g-CN/BiOBr can function as a type-II heterojunction. In this heterojunction, the electrons and holes can effectively be separated at the interface. Moreover, we find that the electronic structure and band alignment of g-CN/BiOBr(001) can be tuned using external electric fields. It is also noteworthy that the optical absorption peak in the visible region is enhanced under the action of the electric field. The electric field may even improve the optical properties of the g-CN/BiOBr(001) heterostructure. Given the results of our calculations, it seems that g-CN/BiOBr(001) may be significantly superior to visible light photocatalysis.