The direct Z-scheme character and roles of S vacancy in BiOCl/Bi 2 S 3 -(001) heterostructures for superior photocatalytic activity: a hybrid density functional investigation.

Given some current speculations and controversies regarding the type of BiOCl/Bi 2 S 3 -(001) heterostructure in experiments, it is of great importance to clarify these controversies and further explain the relevant experimental results. In this work, based on first-principles hybrid density functional calculations, it is verified that the BiOCl/Bi 2 S 3 -(001) heterostructure is a direct Z-scheme photocatalyst with high photo-generated carrier separation efficiency and strong redox ability that can react with O 2 and OH - to produce photocatalytic active species of superoxide ions (˙O 2 - ) and hydroxyl radicals (˙OH), respectively. This is consistent with the experimental findings and explains the excellent photocatalytic performance of the BiOCl/Bi 2 S 3 -(001) heterostructure in experiments. Besides, excitingly, it is found that the optical absorption, built-in electric field intensity, interlayer recombination probability, hydrogen evolution reaction ability, and the difference in electron-hole mobility are further enhanced via S vacancy introduction in BiOCl/Bi 2 S 3 -(001). Therefore, the significant roles of S vacancy in further improving the photocatalytic properties of the BiOCl/Bi 2 S 3 -(001) heterostructure are profoundly revealed. This work can provide valuable theoretical insights for designing the superior direct Z-scheme BiOCl/V S -Bi 2 S 3 -(001) heterostructure with promising photocatalytic properties.