Typical layered structure bismuth-based photocatalysts for photocatalytic nitrogen oxides oxidation.

Traditional NO treatment methods require external reducing reagents and harsh reaction conditions, which is not conducive to effectively eliminate NO at low concentration, especially at ppb levels. Fortunately, low concentration NO can be removed by photocatalytic oxidation under mild reaction conditions. Bismuth (Bi)-based photocatalysts with the layered structure have obtained considerable concerns of photocatalytic NO oxidation. This review focused on typical layered Bi-based photocatalysts (BiWO, BiOCO, BiOY (YCl, Br, and I), BiOIO, and BiOCOOH) with the structure of [BiO] layer for photocatalytic NO oxidation. The strategies (morphological control, defect engineering, heterostructure construction, etc.) to improve photocatalytic oxidation activity were summarized. Furthermore, the mechanism involving various free radicals (hydroxyl radical, superoxide radical, etc.) of photocatalytic oxidation of NO was proposed. In addition, the non-NO selectivity was also illuminated. Lastly, the current drawbacks and further research directions for photocatalytic NO oxidation were elaborated. The development of photocatalysts with high photocatalytic activity, wide light absorption range, and non-NO selectivity is the focus of future research. This review aims to provide a pandect and theoretical guidance for the practical application of photocatalytic oxidation of NO.