Boosting the photocatalytic CO₂ reduction reaction over BiOCl nanosheet via Cu modification

The development of photocatalytic reduction of CO₂ is hindered by slow surface reaction kinetics due to the high activation barrier of CO₂ and the lack of activation centers in the photocatalyst. To overcome these limitations, this study focuses on enhancing the photocatalytic performance through incorporating Cu atoms into BiOCl. By introducing a minute amount of Cu (0.18 wt%) into BiOCl nanosheets, significant improvements were achieved, with a CO yield of 38.3 µmol g^-1 from CO₂ reduction, surpassing that of pristine BiOCl by 50%. To explore the surface dynamics of CO₂ adsorption, activation and reactions, in situ DRIFTS was employed. Theoretical calculations were further performed to elucidate the role of Cu in the photocatalytic process. The results demonstrate that the incorporation of Cu into BiOCl induces surface charge redistribution, which facilitates efficient trapping of photogenerated electrons and accelerates the separation of photogenerated charge carriers. Furthermore, Cu modification on BiOCl effectively lowers the activation energy barrier by stabilizing the COOH* intermediate, thereby turning the rate-limiting step from COOH* formation to CO* desorption and boosting the CO₂ reduction process. This work unveils the atomic-level role of modified Cu in enhancing the CO₂ reduction reaction and presents a novel concept for achieving highly efficient photocatalysts.