A nitrogen fixation strategy to synthesize NO via the thermally assisted photocatalytic conversion of air

Abstract

Developing a novel strategy for energy-efficient and clean synthesis of NO from distributed sources is highly desirable. Herein, we present a facile and green method to synthesize NO through the thermal-assisted photocatalytic oxidation of N₂ using simulated air as the reactant in a flow reactor. The TiO₂/WO₃ heterostructured nanorods were constructed and exhibited good activity for NO photosynthesis assisted by heating in the range of 200–350 °C. The yield rate of NO reached 0.16 mmol g⁻¹ h⁻¹ at 300 °C with a quantum efficiency of 0.31% at 365 nm. ¹⁵N isotope labeling experiments proved the origin of NO from N₂ oxidation. Experimental and theoretical results revealed that the lattice oxygen in the heterostructures participated in the photooxidation reaction of N₂, and the electron transfer from WO₃ to TiO₂ at the interface of the heterojunction under illumination could facilitate the adsorption of N₂ and the formation of NO* intermediates and thus enhanced the photocatalytic N₂ oxidation performance. Importantly, the solar-driven oxidation generated NO can be directly used for the synthesis of fine chemicals including nitric acid and β-nitrostyrolene. Our work opens a new avenue for nitrogen fixation via solar-driven N₂ oxidation from distributed sources of air.