Double defects cooperatively mediated BiOClBr-OV for efficient round-the-clock photocatalytic CO2 reduction

In recent years, the production of high-value solar fuels through photocatalytic reduction of CO2 has received significant attention. However, the low photocatalytic activity and intermittent nature of solar light contributing to low production rates have hindered its large-scale application. This study successfully constructed BiOClBr-OV with two defects (Cl/Br substitution, oxygen vacancy), which not only enhanced the catalytic activity but also opened the door to round-the-clock photocatalytic reduction of CO2. Under visible light exposure, the double defects exhibit a synergistic enhancement effect and outstanding electron storage capacity, resulting in 6.8 times and 34.2 times increase in the photocatalytic activity and electron storage capacity, respectively, compared to the pristine BiOCl. Additionally, BiOClBr-OV with surface oxygen defects exhibits frustrated Lewis pair (FLP) catalytic behavior, effectively changing the adsorption mode of CO2 and enhancing its activation ability. Simultaneously, the unsaturated surface Bi ions of BiOClBr-OV are the electron storage centers, achieving the three-in-one combination of adsorption sites, FLP active sites, and electron storage sites, leading to excellent photocatalytic activity. Finally, the catalytic mechanism and possible reaction pathways are thoroughly explained through in-situ technologies and density functional theory (DFT) calculations. This work introduces a novel multi-sites unified catalyst design strategy, providing deep insight into the photocatalytic CO2 reduction process and making the application of Bi-based semiconductors in round-the-clock photocatalysis possible.