Constructing BiOBr 1- x I x - y with Abundant Surface Br Vacancies for Excellent Visible-Light Photodegradation Capability of High-Concentration Refractory Contaminants.

Bismuth oxybromide (BiOBr) is a promising photocatalytic semiconductor material due to its unique hierarchical structure and band structure. However, its photocatalytic applications are restricted due to its narrow visible-light absorption range and poor photooxidation capability. In this study, BiOBr 1- x I x - y with rich surface Br vacancies (BrVs-rich BiOBr 1- x I x - y ) was created via a facile indirect substitution strategy. Benefiting from the broadened visible-light response range and reduced recombination rate of photogenerated carriers, BiOBr 1- x I x - y shows excellent visible-light photodegradation ability for high-concentration refractory contaminants, such as phenol, tetracycline, bisphenol A, rhodamine B, methyl orange, and even real wastewater. At the same time, the Br vacancies can regulate the band structure of BiOBr 1- x I x - y and serve as trap states to promote charge separation, thus facilitating surface photoredox reactions. An in-depth investigation of the Br vacancy effect and photodegradation mechanism was conducted. This novel study revealed the significance of Br vacancies in enhancing the photocatalytic performance of BiOBr under visible light, providing a promising strategy for improving the utilization efficiency of sunlight in wastewater treatment.