Ammonia (NH₃) is attracted as a potential carbon free energy carrier and as important feedstock for most of the fertilizers, chemicals, pharmaceutical related products. NH₃ is industrially produced by conventional Haber–Bosch process under harsh experimental conditions (high temperature and high pressure), and this process requires high-energy consumption and produces large amount of CO₂ emissions into the atmosphere. Therefore, there is an urgent need to develop an alternative and sustainable route for NH₃ production under ambient conditions. Recently, electrocatalytic N₂ reduction to NH₃ production has attracted as a potential approach, but achieving high NH₃ yield and Faradaic efficiency, and avoiding competitive hydrogen-evolution reaction (HER) are still challenging. Nitrate/nitrite (NO₃⁻/NO₂⁻) is the widely reported contaminant for eutrophication and carcinogens, which can be utilized as a nitrogen resource for electrocatalytic NO₃⁻/NO₂⁻ reduction to NH₃ (NRA) via eight/six-electron transfer process. Unfortunately, electrocatalytic NRA using metal nanomaterials are rarely investigated. In this review, we discuss the electrocatalytic NRA performance containing reactivity, selectivity, Faradaic efficiency and cycling stability of metal nanocatalysts, bio-inspired metalloenzymes and bioelectrochemical system. After this overview, we investigate the key factors, rate-determining step and the reaction mechanism that controlling the NRA performance. Finally, we summarize the challenges and future pathways guiding the design of effective nanomaterials and reaction systems to promote the industrial application of electrocatalytic NRA.

氨（NH ₃）被吸引为潜在的无碳能源载体，并作为大多数肥料，化学药品和制药相关产品的重要原料。NH ₃是在恶劣的实验条件（高温和高压）下通过常规的Haber-Bosch工艺工业生产的，该工艺需要消耗大量能量，并向大气中排放大量CO ₂。因此，迫切需要开发一种在环境条件下生产NH ₃的替代且可持续的途径。近来，将电催化的N ₂还原为NH _3的生产已成为一种潜在的方法，但实现了较高的NH _3。产率和法拉第效率，以及避免竞争性的氢演化反应（HER）仍然具有挑战性。硝酸盐/亚硝酸盐（NO ₃ ^- / NO ₂ ^- ）可以富营养化和致癌物的广泛报道的污染物，其可以被用作氮源为电催化NO ₃ ^- / NO ₂ ^-还原为NH ₃（NRA）通过八/六电子传输过程。不幸的是，很少研究使用金属纳米材料的电催化NRA。在这篇综述中，我们讨论了包含金属纳米催化剂，生物启发的金属酶和生物电化学系统的反应性，选择性，法拉第效率和循环稳定性的电催化NRA性能。在此概述之后，我们将研究控制NRA性能的关键因素，速率确定步骤和反应机理。最后，我们总结了指导有效的纳米材料和反应系统设计以促进电催化NRA的工业应用的挑战和未来的途径。