Review on Photocatalytic Oxidation of Hg⁰ by BiOIO₃-Based Materials

Photocatalytic oxidation of Hg0 is an environmental protection technology that removes Hg0 from flue gas by oxidizing Hg0 using active species produced by photocatalysts under light conditions. For the past few years, BiOIO3 has drawn a lot of attention from scientists because of its special layered structure and internal polarity. In this work, we first introduce the photoelectrochemical properties of BiOIO3, and the modification methods of BiOIO3 are summarized according to different photocatalytic mercury oxidation mechanisms. Second, density functional theory is used to calculate the energy bands, density of states, and work function to reveal the changes in the microscopic physicochemical properties of the modified catalysts. Then, the synthesis methods of BiOIO3 and its composites are summarized and the effects of different flue gas components on the photocatalytic oxidation of Hg0 are investigated. Finally, the applications of BiOIO3 in other fields are briefly introduced, suggesting that the use of such catalysts for synergistic treatment in the fields of mercury removal and carbon dioxide reduction is a direction to be explored in the future. Furthermore, the modification of the BiOIO3 series catalysts according to their unique layered structure will be the next focus of their use in photocatalytic mercury oxidation. This work contributes to the development of more efficient BiOIO3 series photocatalysts.