Research progress on removal of mercury from flue gas by photocatalytic oxidation of bismuth oxyhalide: A review

Photocatalytic oxidation is a promising technology that can alleviate energy shortages and pollution. Bismuth oxyhalide is a new photocatalytic material, which has attracted much attention due to its unique crystal geometry, high photocatalytic performance and adjustable electronic structure. In this work, we firstly review the latest research progress in the field of bismuth oxyhalide photocatalysts for mercury removal. The advantages of bismuth oxyhalide for mercury removal are described in detail. Secondly, the synthesis of bismuth oxidized halides, mainly by hydrothermal method, is systematically presented. According to the different mechanism of mercury removal, the modification strategies including heterogeneous structure construction and element doping were summarized to improve the performance of photocatalytic mercury removal. The mercury removal mechanism of bismuth oxyhalide photocatalysts was revealed by density functional theory (DFT). Finally, it is pointed out that the key to improve the photocatalytic performance is to promote the separation of electron hole pairs, and consider the synergistic effect between different components of flue gas is also the focus of the next work. This work provides help for the innovative development and exploration of photocatalysts for bismuth oxyhalide.