Constructing g-C3N4/SnO2 S-scheme heterojunctions for efficient photocatalytic NO removal and low NO2 generation

The facile fabrication of g-C3N4/SnO2 S-scheme heterojunctions for photocatalytic removal of NO under visible light is reported. Optical and electrochemical investigations indicate the formation of these heterojunctions that enable bending at the interface of g-C3N4 and SnO2 and give rise to an efficient separation. A high photocatalytic 500-ppb NO removal performance of 35% and low NO2 generation of 2% are realized after 30 min of visible light irradiation upon the g-C3N4/SnO2 heterojunction with 30% of g-C3N4 addition. In contrast, the bare g-C3N4 extensively produces NO2 greater than 12% compared to 30% from the g-C3N4 sample. This study also shows that the g-C3N4/SnO2 heterojunction is a stable catalyst system and superoxide radicals play a crucial role in the photocatalytic NO removal. Since the preparation of the g-C3N4/SnO2 heterojunction reported in this work is straightforward, it can potentially enable the preparation of highly robust visible-light-driven photocatalysts to remove NO pollution.