Enhancement of photocatalytic activities in hierarchical BiOBr microflowers induced by oxygen vacancies

Bismuth oxyhalides have attracted more and more attention as promising photocatalysts. Oxygen vacancies on the surface of BiOBr play an important role in enhancing photocatalytic activity. In this paper, we present a facile method to prepare hierarchical BiOBr microflowers with surface oxygen vacancies by the solvothermal synthesis route in the presence of urea. The content of oxygen vacancies on the surface of hierarchical BiOBr microflowers can be tuned by the amount of urea used in the synthesis process. Moreover, it was found that hierarchical BiOBr microflowers with oxygen vacancies exhibited much better photocatalytic activity for photocatalytic degradation of Rhodamine B than the BiOBr without oxygen vacancies. Furthermore, experimental results revealed that oxygen vacancies can promote effective separation and transport of photo-generated charges, which is beneficial for photocatalytic performance of BiOBr. This study establishes an in-depth understanding of defective oxygen vacancies structures in Bismuth oxyhalides based photocatalysts.