Investigation of band offsets of interface BiOCl:Bi2WO6: a first-principles study

Density functional theory calculations are performed to study the band offsets at the interface of two photocatalytic materials BiOCl:Bi2WO6. It is found that the W-O bonded interface shows the most stability. An intrinsic interface fails to enhance the charge-carrier separation due to the improper band alignment between these two materials. Sulfur (S) is proposed to replace the bulk oxygen (O) site and thus tune the band edges of BiOCl to enhance the photocatalytic performance of the heterojunction. Furthermore, the presence of S provides an extra charge to generate a clean interface with minimal gap states that also benefits carrier migration across the heterojunction.