Theoretical Study on two Direct Z‐scheme Heterostructure Photocatalysts for Efficient Photohydrolysis and Catalytic Oxidation of Formaldehyde, CdS/BiOF and g‐C3N4/BiOF

Abstract

AbstractGraphitic carbon nitride (g‐C3N4) and cadmium sulfide (CdS) have attracted much attention due to their suitable band gap and excellent photocatalytic activity.Although BiOF cannot respond to visible light due to its ultra‐high band gap (3.6 eV), its strong oxidizing property is attractive to researchers.Therefore, in this study, we employed first‐principles studies to design mediator‐free CdS/BiOF and g‐C3N4/BiOF heterostructured photocatalysts. Then, the band structures, optical properties, charge transfer and radical generation reactions of the CdS/BiOF and g‐C3N4/BiOF heterostructures were calculated, respectively.The results show that the heterostructure exhibits hydrogen evolution and reactive radical generation potential under visible light irradiation. In addition, an interfacial electric field is generated during the interfacial charge transfer process of the heterostructure, and the generated interfacial electric field improves the separation efficiency of photogenerated carriers. This improvement is attributed to CdS (or g‐C3N4) acting as an electron acceptor, enabling the migration of photogenerated carriers at the interface to conform to the direct z‐scheme. Furthermore, we designed a method for catalytic oxidation of formaldehyde on the surface of heterostructures by exploiting the strong oxidizing properties of BiOF, which broadened the applicable scope of CdS/BiOF and g‐C3N4/BiOF heterostructures. This work facilitates the design of novel Z‐scheme photocatalysts and provides new insights into the Z‐scheme charge transfer mechanism in the field of solar energy conversion.