Effects of surface chlorine atoms on charge distribution and reaction barriers for photocatalytic CO2 reduction

Photocatalytic CO2 reduction to produce high value-added carbon-based fuel has been proposed as a promising approach to mitigate global warming issues. However, the conversion efficiency and product selectivity are still low due to the sluggish dynamics of transfer processes involved in proton-assisted multi-electron reactions. Lowering the formation energy barriers of intermediate products is an effective method to enhance the selectivity and productivity of final products. In this study, we aim to regulate the surface electronic structure of Bi2WO6 by doping surface chlorine atoms to achieve effective photocatalytic CO2 reduction. Surface Cl atoms can enhance the absorption ability of light, affect its energy band structure and promote charge separation. Combined with DFT calculations, it is revealed that surface Cl atoms can not only change the surface charge distribution which affects the competitive adsorption of H2O and CO2, but also lower the formation energy barrier of intermediate products to generate more intermediate ∗COOH, thus facilitating CO production. Overall, this study demonstrates a promising surface halogenation strategy to enhance the photocatalytic CO2 reduction activity of a layered structure Bi-based catalyst.