Photodriven Disproportionation of Nitrogen and Its Change to Reductive Nitrogen Photofixation

Nitrogen fixation is an essential process for sustaining life. Tremendous efforts have been made on the photodriven fixation of nitrogen into ammonia. However, the disproportionation of dinitrogen to ammonia and nitrate under ambient conditions has remained a grand challenge. In this work, the photodriven disproportionation of nitrogen is realized in water under visible light and ambient conditions using Fe-doped TiO₂ microspheres. The oxygen vacancies associated with the Fe dopants activate chemisorbed N₂ molecules, which can then be fixed into NH₃ with H₂ O₂ as the oxidation product. The generated H₂ O₂ thereafter oxidizes NH₃ into nitrate. This disproportionation reaction can be turned to the reductive one by loading plasmonic Au nanoparticles in the doped TiO₂ microspheres. The generated H₂ O₂ can be effectively decomposed by the Au nanoparticles, resulting in the transformation of the disproportionation reaction to the completely reductive nitrogen photofixation.