Oxygen vacancy-rich CeO2/BiOBr was prepared via solvothermal method combined with rGO to design a Z-scheme heterojunction, which was used for photocatalytic oxidation of gaseous elemental mercury. The Z-scheme heterojunction constructed by interface engineering significantly promotes charge carriers transfer at the interface. Moreover, the surface oxygen vacancies and Ce3+/Ce4+ redox centers tend to capture electrons to accelerate the Z-scheme path of charge transfer to maintain efficient redox performance and facilitate molecular oxygen activation to boost photocatalytic removal of Hg-0. The collaboration of oxygen vacancies, Ce3+/Ce4+ and heterojunction enhances the photocatalytic oxidation activity, which achieves a removal efficiency of 76.53%, which is 1.29 times that of BiOBr and 1.91 times that of CeO2. The effect of actual flue gas components (SO2, NO and HCl) on the performance of photocatalytic Hg-0 removal was further investigated. Combined with DFT theoretical calculations, the photocatalytic reaction mechanism of Z-scheme heterojunction with oxygen vacancies-rich was proposed. It provides a feasible strategy for the development of high-efficiency Z-scheme heterojunction photocatalytic system for environmental purification. (c) 2020 Elsevier Inc. All rights reserved.