Surface Reorganization Leads to Enhanced Photocatalytic Activity in Defective BiOCI

Introducing defects into semiconductor photo-catalysts has been identified as an effective approach to extend the visible-light absorption and achieve high-efficiency solar energy conversion. However, the band gap model system of defect states may not truly describe the evolutions in real materials as the narrower band gap would limit the photocatalytic activity via suppressing the charge separation. Here, we report that reorganizing the surface termination in a defective semiconductor plays a key role in determining the photocatalytic performance. We directly observed that the surface reorganizations are accompanied by the formation of defects in layered structured bismuth oxychloride (BiOCI). Both experimental and theoretical results demonstrate that varying terminations have strong effects on the electronic structure and electron-hole pair recombination, which is shown to be the driving force of the promotion of visible-light photocatalytic activity in BiOCI. We also reveal that the surface reorganization induces a novel transfer path and high-dielectric surface to prevent the trapping of charge carriers, highlighting an efficient way of improving the photocatalytic activity by surface reorganization.