Green electrosynthesis of nitric acid/nitrate via NO/N2 electrocatalytic oxidation: a sustainable route for nitrogen resource utilization.

This review comprehensively summarizes the research progress in the electro-catalytic oxidation of nitrogen oxides (NO) and nitrogen gas (N2) to produce nitric acid/nitrate. In response to the global imbalance in the nitrogen cycle and the problem of NO pollution, the traditional high-energy consumption ammonia oxidation (Haber-Ostwald process) technology and end-of-pipe treatment techniques have limitations such as resource waste and secondary pollution. However, electro-catalytic technology can directly convert NO or N2 into high-value nitric acid/nitrate under mild conditions, achieving the resource utilization of pollutants and providing a new approach for building a low-carbon nitrogen cycle system. This review elaborates on the thermodynamic basis, reaction mechanism, and key performance indicators of electro-synthesis of nitric acid/nitrate, focuses on summarizing the design strategies and latest progress in noble metal, non-noble metal, and non-metal catalysts, discusses the electrolyte effect, electrolytic cell structure optimization, and challenges in actual flue gas treatment, and introduces the role of in situ characterization and theoretical calculation in mechanism research. Meanwhile, this paper points out that electrochemical synthesis technology has broad prospects in distributed nitric acid production, industrial flue gas resource recovery, and renewable energy storage, but still needs to overcome problems such as catalyst stability, system adaptability, and engineering scaling. Finally, this paper clearly proposes future comprehensive and sustainable research priorities, including the development of high-performance catalysts, in-depth exploration of reaction mechanisms, promoting system engineering innovation, and achieving interdisciplinary integration.