In this study, a series of BiOI/TiO2 heterostructure photocatalysts were prepared by a facile one-pot hydrothermal method. All samples were characterized by XRD, TEM and other techniques. The results showed that the heterostructures between BiOI and TiO2 were formed successfully. The photoactivities of the samples were tested by catalytic oxidation of Hg-0 and BT-4 showed the highest removal efficiency, reaching up to 82.5%. Moreover, the trapping experiments indicated that center dot O2- and h(+) were the main reactive components for Hg-0 removal. Finally, a possible mechanism was proposed: A Z-scheme electron/hole transport mechanism was the main reason for the enhanced photoactivity. [GRAPHICS] .