Toward Mild Conditions for N2 Activation: Progress and Challenges from Nitrogenase to Biomimetic Artificial Catalysts

Abstract Nitrogen (N2), as the most abundant gas in the atmosphere, poses a long-standing challenge in chemistry and biochemistry due to its high bond energy (≈941 kJ·mol–1) and thus low reactivity under mild conditions. In nature, nitrogenase can reduce N2 to ammonia at ambient temperature and pressure, while industry relies on the energy-intensive Haber–Bosch process for ammonia synthesis. This paper systematically reviews the mechanisms and catalytic progress in biological nitrogen fixation and industrial ammonia synthesis, with a focus on the structure and catalytic mechanism of nitrogenase, as well as the catalytic mechanisms and green pathways for industrial ammonia production. It further summarizes the design strategies and recent advances in artificial nitrogen fixation catalysts inspired by nitrogenase. For example, a biomimetic iron–molybdenum dual-atom catalyst on carbonized delignified wood (FeMo-CDW) recently achieved an NH3 production rate of 336.03 μg·h–1·cm–2 under acidic conditions, while an Fe single-atom catalyst supported on monolayer MoS2 delivered an NH3 production rate of 97.5 ± 6 μg·h–1·cm–2, underscoring the practical promise of nitrogenase-inspired systems. By reviewing molecular catalysts, metal sulfides/carbides, single-atom catalysts, and related directions, this review paper outlines future development pathways for efficient nitrogen fixation catalytic systems under mild conditions, offering theoretical insights and design principles for breakthroughs in green ammonia synthesis technologies.