Photocatalytic Dinitrogen Reduction to Ammonia over Biomimetic FeMoSx Nanosheets

Reduction of atmospheric dinitrogen (N₂) to ammonia (NH₃) using water and sunlight in the absence of sacrificial reducing reagents at room temperature is very challenging and is considered an eco-friendly approach to meet the rapidly increasing demand for nitrogen storage, fertilizers, and a sustainable society. Currently, ammonia production via the energy-intensive Haber–Bosch process causes ∼350 million tons of carbon dioxide (CO₂) emission per year. Interestingly, natural N₂ fixation by the nitrogenase enzyme occurs under ambient conditions. Unfortunately, N₂ fixation on biomimetic catalysts has rarely been studied. To mimic biological nitrogen fixation, herein, we synthesized the novel iron molybdenum sulfide (FeMoS_x) micro-/nanosheets via a simple hydrothermal approach for the first time. Further, we successfully demonstrated the photochemical conversion of N₂ to NH₃ over a biomimetic FeMoS_x photocatalyst. The estimated yield is around 99.79 ± 6.0 μmol/h/g photocatalyst with a quantum efficiency of ∼0.028% at 532 nm visible-light wavelength. Besides, we also systematically studied the influence of key factors to further improve NH₃ yields. Overall, this study paves a new pathway to fabricate carbon-free, photochemical N₂ fixation materials for future applications.