Rational fabrication flowerlike BiOBr with oxygen vacancy for enhancing photocatalytic performance to remove gaseous mercury

In this work, the different morphologies of BiOBr photocatalyst were successfully synthesized by mixing method, hydrothermal method, and calcination method for gas-phase Hg-0 photocatalytic oxidation. The physicochemical properties of the BiOBr were characterized by XRD, SEM, TEM analysis etc. It was found that all BiOBr photocatalyst samples showed excellent ability photocatalytic oxidation of Hg-0 under visible light irradiation, and the BiOBr-C sample prepared by calcination method showed the highest mercury removal efficiency about 60.5% among all samples. This can be attributed to the morphology of flowerlike BiOBr-C can enhance the electron transfer ability in three-dimensional space. Besides, the calcination method is beneficial to enhance the formation of oxygen vacancy and the introduction of oxygen vacancies can efficiently improve the ability of electron capture, and further promote the photocatalytic performance of BiOBr-C. Finally, a possible photocatalytic reaction mechanism was proposed.