Light Control-Induced Oxygen Vacancy Generation and In Situ Surface Heterojunction Reconstruction for Boosting CO Reduction.

The weak adsorption of CO and the fast recombination of photogenerated charges harshly restrain the photocatalytic CO reduction efficiency. The simultaneous catalyst design with strong CO capture ability and fast charge separation efficiency is challenging. Herein, taking advantage of the metastable characteristic of oxygen vacancy, amorphous defect BiOCO (named BOC) was built on the surface of defect-rich BiOBr (named BOB) through an in situ surface reconstruction progress, in which the CO in solution reacted with the generated Bi around the oxygen vacancies. The in situ formed BOC is tightly in contact with the BOB and can prevent the further destruction of the oxygen vacancy sites essential for CO adsorption and visible light utilization. Additionally, the superficial BOC associated with the internal BOB forms a typical heterojunction promoting the interface carriers' separation. Finally, the in situ formation of BOC boosted the BOvB and showed better activity in the photocatalytic reduction of CO into CO (three times compared to that of pristine BiOBr). This work provides a comprehensive solution for governing defects chemistry and heterojunction design, as well as gives an in-depth understanding of the function of vacancies in CO reduction.