Oxygen Vacancy-Mediated Bi─O Unsaturation Coordination in BiOCl for Efficient Photocatalytic Water Purification

The stable modulation of the local charge distribution behavior induced by unsaturation sites within photocatalysts continues to pose a significant challenge in the quest to achieve notable enhancements in photocatalytic activity. Herein, we harnessed the hydrogen annealing reduction technique to deliberately introduce oxygen vacancies (OVs) into the BiOCl lattice for constructing the OVs-Bi-O structure, which decreases the valence state of Bi, and diminishes the Bi─O coordination, further establishing a charge asymmetric region within the material. This distinctive structural arrangement facilitates the sufficient migration of electrons to adjacent Bi sites that are closely linked to the OVs, significantly promoting the capture capability of electrons, leading to more adsorption and activation of water and oxygen as well as the conversion of reactive oxygen radicals. The engineered OVs-BiOCl variant showcases potential photocatalytic prowess, boasting a satisfactory photocatalytic application than that of its unmodified BiOCl counterpart. Under low-light conditions, this variant impressively achieves a ∼98.1% removal efficiency for RhB, while concurrently achieving an almost complete elimination of E. coli. This finding presents an insightful approach for manipulating unsaturation coordination active sites through the strategic introduction of controllable defects and elucidates the impact of unsaturation coordination on photocatalytic efficiency.