Eun-Su Yoon  Chang-Hyeon Kim  Kyung-Won Jeon  Jae-Oh Shim

Vol. 32,  No. 1, pp. 14-26, Mar.  2026
10.7464/ksct.2026.32.1.14

Ammonia synthesis Nitrate reduction Electrochemical catalysis Non-noble metal catalysts carbon neutrality

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This paper provides a comprehensive overview of the recent research trends in the electrochemical nitrate reduction reaction (NO3RR) as an environmentally sustainable route for ammonia synthesis. The conventional Haber-Bosch process suffers from intrinsic limitations, including high-temperature and high-pressure operation requirements and reliance on fossil-fuel-derived hydrogen, resulting in substantial CO2 emissions. Consequently, the development of alternative ammonia production technologies compatible with carbon neutrality has become imperative. NO3RR offers both environmental remediation and resource recovery benefits by removing nitrate, a major contaminant in aquatic environments, while simultaneously producing NH3. This review first examines the historical development and current status of the Haber-Bosch process, followed by an analysis of NO3RR as a carbon-reducing and environmentally benign ammonia production pathway. The multi-electron transfer mechanism of nitrate reduction is summarized and the key processes governing the reaction selectivity and kinetics are the NO3– → NO2– initial activation step and the NH2OH → NH3 final hydrogenation step. Subsequently, catalytic systems based on noble metals are compared, focusing on how surface structure, defect engineering, and alloying strategies achieve high Faradaic efficiency and NH3 selectivity. Non-noble metal catalysts are also discussed, emphasizing cost-effective yet high-performance design principles such as interfacial electronic modulation, oxygen vacancy engineering, single-atom catalytic sites, and synergistic alloy effects. Overall, this paper suggests that NO3RR-based electrochemical ammonia synthesis could potentially complement or even replace the Haber-Bosch process. Lastly, future directions in catalyst design and the practical applicability of NO3RR for wastewater treatment are proposed.