Revealing the role of oxygen vacancies in bimetallic CdBiO2Br ultrathin nanosheets for boosting visible-light photocatalytic activity

The development of photocatalysts with high-efficiency spatial separation of photoinduced carriers and activation of molecular oxygen is of great significance in the degradation of organic contaminants. Herein, we successfully fabricate ultrathin CdBiO2Br nanosheets with Sille ' n structure and different oxygen vacancies (OVs) concentration employing a simple ionothermal method. Furthermore, the photocatalytic activity was evaluated employing tetracycline, ciprofloxacin, and rhodamine B as the target contaminants under visible light irradiation. Among which, oxygen-vacancy rich (ROV) CdBiO2Br showed the highest photocatalytic performance compared to oxygen-vacancy deficient (DOV) CdBiO2Br and bulk CdBiO2Br. In addition, the intermediate degradation products were proved to show a significant decrease in toxicity by microbial toxicology experiments. Based on a series of characterization analyses, the intrinsic factors of ROV CdBiO2Br for enhanced photocatalytic performance are studied, and a possible photocatalytic mechanism is summarized. This work reinforces the idea that defect engineering and surface structure engineering affect photocatalytic activity simultaneously.