The reduction of dinitrogen (N₂) by proton and electron transfer remains a significant challenge in catalytic processes. This review discusses the current understanding of nitrogen fixation, highlighting the mechanisms involved in biological and artificial systems. Ammonia is essential for plant growth, and while the Haber–Bosch process is widely used for its production, it is energy-intensive. Natural nitrogen fixation by nitrogenases is less efficient but occurs through a series of proton and electron transfer steps. Recent advances in understanding nitrogen fixation, molecular catalysts, and electrochemical reduction have provided insights into the challenges of efficiently reducing N₂. Three main reaction mechanisms for nitrogen reduction are described: dissociative, alternating associative, and distal associative. The binding strength of nitrogen to the catalyst is crucial for ammonia selectivity. Stronger nitrogen binding increases the overpotential required for reduction, necessitating an optimal balance between overpotential and selectivity. The Haber–Bosch process remains the most efficient for ammonia synthesis, but alternative methods using proton and electron transfer are being explored. Molybdenum-based catalysts have shown promise in dinitrogen reduction, with systems like the Schrock catalyst demonstrating high efficiency. However, challenges such as hydrogen evolution and energy requirements persist. Electrochemical reduction of dinitrogen at heterogeneous surfaces is also being studied, with Ru and Rh surfaces showing potential. Despite progress, the energy input required for electrochemical nitrogen reduction is still higher than that of the Haber–Bosch process. The review emphasizes the need for further research to develop more efficient catalysts that can reduce dinitrogen with minimal energy input and high selectivity. While the Haber–Bosch process remains dominant, alternative methods are being explored to address energy and environmental concerns. The challenges in nitrogen reduction highlight the importance of understanding the underlying mechanisms and developing new catalysts that can overcome these barriers.The reduction of dinitrogen (N₂) by proton and electron transfer remains a significant challenge in catalytic processes. This review discusses the current understanding of nitrogen fixation, highlighting the mechanisms involved in biological and artificial systems. Ammonia is essential for plant growth, and while the Haber–Bosch process is widely used for its production, it is energy-intensive. Natural nitrogen fixation by nitrogenases is less efficient but occurs through a series of proton and electron transfer steps. Recent advances in understanding nitrogen fixation, molecular catalysts, and electrochemical reduction have provided insights into the challenges of efficiently reducing N₂. Three main reaction mechanisms for nitrogen reduction are described: dissociative, alternating associative, and distal associative. The binding strength of nitrogen to the catalyst is crucial for ammonia selectivity. Stronger nitrogen binding increases the overpotential required for reduction, necessitating an optimal balance between overpotential and selectivity. The Haber–Bosch process remains the most efficient for ammonia synthesis, but alternative methods using proton and electron transfer are being explored. Molybdenum-based catalysts have shown promise in dinitrogen reduction, with systems like the Schrock catalyst demonstrating high efficiency. However, challenges such as hydrogen evolution and energy requirements persist. Electrochemical reduction of dinitrogen at heterogeneous surfaces is also being studied, with Ru and Rh surfaces showing potential. Despite progress, the energy input required for electrochemical nitrogen reduction is still higher than that of the Haber–Bosch process. The review emphasizes the need for further research to develop more efficient catalysts that can reduce dinitrogen with minimal energy input and high selectivity. While the Haber–Bosch process remains dominant, alternative methods are being explored to address energy and environmental concerns. The challenges in nitrogen reduction highlight the importance of understanding the underlying mechanisms and developing new catalysts that can overcome these barriers.