Oxygen vacancy-rich BiO2-x: Super-active co-catalyst on g-C3N4 for efficient visible-light photocatalytic CO2 reduction

Photoreduction CO2 to hydrocarbons are the sustainable and green methods to solve energy shortages and environmental pollution problems. Therefore, the development of efficient and environment-friendly photocatalysts remains a huge challenge, while coupling co-catalyst on traditional photocatalysts is a potential approach for improving photocatalytic activity. Here, a novel BiO2-x co-catalyst coupled g-C3N4 photocatalyst was prepared by a simple hydrothermal approach for the photocatalytic reduction of CO2. The experimental results proved that BiO2-x/g-C3N4 composites played a vital part for promoting the photocatalytic capability. The 20 % BiO2-x/g-C3N4 composites exhibited the best photocatalytic capability under the simulated visible-light. A maximum yield of CO (42.29 μmol/gcat) and CH4 (7.2 μmol/gcat) were obtained, which were 3.8 and 2.5 times that over pure g-C3N4, and its apparent quantum yield (AQY) was 1.5 % at 420 nm. According to the characterization results, the significantly increased photocatalytic activity could be ascribed to larger specific surface area, stronger visible-light absorption properties and more effective separation and transfer of photogenerated electron-hole pairs. Our finding provides a certain reference for the development and application of novel co-catalyst.