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 Sillén 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.