Photochemical Ammonia Synthesis over Reduced Polyoxovanadate-Intercalated\nDefective ZnAl Layered Double Hydroxide Nanosheets

Abstract

The\nexploration of efficient and stable N₂ fixation\nphotocatalysts featuring a broad absorption spectrum and N₂ fixation active sites has become specifically conspicuous. Herein,\na series of reduced polyoxovanadates (POVs) were intercalated into\ncopper-induced ZnAl layered double hydroxide (0.5%-ZnAl LDH) nanosheets\nwith oxygen vacancies via an anion exchange strategy toward green\nammonia production. The intervalence charge transfer arising from\nmixed-valence POV materials is responsible for its light-harvesting\nbehavior, and the LDHs lay the foundation for the chemical adsorption\nand activation process of nitrogen molecules; both contributions facilitate\nthe nitrogen photofixation performance of such composite materials.\nAs predicted, the catalytic efficiency of V₃₄/0.5%-ZnAl\nis 7.0 times higher than 0.5%-ZnAl LDH. Therefore, such an all-inorganic\nsystem exhibits an apparent quantum efficiency of 0.3137% at 500 nm.\nThe strategy of “working in tandem” established by POV-based\nlight-absorber species and oxygen vacancies as the sites for N₂ activation is extremely vital for enhanced ammonia formation.\nThis work opens up a versatile insight for the rational design of\nan efficient photo-driven nitrogen-reduction composite catalyst toward\nsustainable ammonia production compared to the industrial Haber–Bosch\nprocess.