Photon localization effect and surface oxygen vacancy enhanced photocatalytic nitrogen fixation performance for nanocrystalline titanium dioxide films

Abstract

Photocatalytic nitrogen fixation has aroused extensive attention as a green and sustainable route for ammonia synthesis under mild conditions. To boost nitrogen fixation efficiency, many approaches have been proposed to overcome the limitations of a high energy barrier, easy recombination of photogenerated electrons–holes and poor light absorption. Oxygen vacancies (OVs) introduced on the surface of photo-catalysts are critical for N₂ molecular activation. Meanwhile, photonic crystals (PCs) can effectively promote the photon capture of catalysts. The focus of this work is to couple titanium dioxide (TiO₂) with oxygen vacancies (TOVs) and silica (SiO₂) photonic crystals (SPCs) for the purpose of synergistically enhancing the photocatalytic nitrogen fixation performance. Experimental results showed that TOV films exhibited better photocatalytic activity than anatase TiO₂ films because the OVs provided more active sites for the chemisorption and activation of nitrogen. The photon localization effect of SPCs could improve the light-harvesting ability of TOVs, leading to further enhancement of the nitrogen photofixation performance of TiO₂. This research provides a novel route for production of ammonia in a clean and low-energy consumption way.