Oxygen Vacancies Mediated Complete Visible Light NO Oxidation via Side-On Bridging Superoxide Radicals.

It is of a great challenge to seek for semiconductor photocatalysts with prominent reactivity to remove kinetically inert dilute NO without NO2 emission. In this study, complete visible light NO oxidation mediated by O2 is achieved over a defect-engineered BiOCl with selectivity exceeding 99%. Well-designed oxygen vacancies on the prototypical (001) surface of BiOCl favored the possible formation of geometric-favorable superoxide radicals (•O2-) in a side-on bridging mode under ambient condition, which thermodynamically suppressed the terminal end-on •O2- associated NO2 emission in case of higher temperatures, and thus selectively oxidized NO to nitrate. These findings can help us to understand the intriguing surface chemistry of photocatalytic NO oxidation and design highly efficient NO x removal systems.