CuOx clusters decorated TiO2 for photocatalytic oxidation of nitrogen in air into nitric oxide under ambient conditions

Abstract

Photocatalytic nitric oxide (NO) synthesis from air is an attractive way to supersede the conventional nitrogen fixation manufacturing technique accompanied by high energy requirements and greenhouse gas emission. The development of efficient photocatalysts for direct solar-driven N2 oxidation to NO without external thermal assistance is highly challenged. Here, CuOx clusters decorated TiO2 nanoflowers with various copper contents are constructed and used for solar-driven air reaction into NO under ambient conditions. When the copper content is 1 wt%, the sample shows the optimal performance with a yield rate of 35.0 mmol m−2 h−1 (7.7 μmol h−1) and an apparent quantum efficiency of 1.77% at 365 nm. A series of in situ and ex situ characterizations reveal Cu2O species and TiO2 support form direct Z-scheme heterojunction over 1%Cu-TiO2. This heterojunction can promote the adsorption and activation of nitrogen and oxygen reactants, leading to the performance enhancement of NO photosynthesis from air. Also, we proposed a possible NO photosynthesis reaction pathway over 1%Cu-TiO2.