Advances in electrocatalytic nitrite reduction to ammonia: Mechanisms, catalyst design, and future perspectives

Electrocatalytic reduction of nitrite to ammonia (NO2RR) is an environmentally friendly and low energy consuming emerging technology with broad prospects. This article reviews the latest developments and explores the mechanism of NO2RR, including key steps such as nitrite adsorption, activation, multi-step reduction, and ammonia desorption. The reaction under both acidic and alkaline conditions are systematically analyzed. At the same time, the article deeply analyzes various catalyst design strategies, such as vacancy engineering, atomically dispersed metal sites, engineering interfaces for synergistic catalysis, hybrid-atom doped catalysts, and molecular catalysts, and summarizes the performance advantages and limitations of each type of catalyst. In addition, methods to improve catalyst selectivity and stability were explored, and challenges faced in this field were pointed out, such as the balance between catalyst activity and stability, complex reaction pathways, insufficient large-scale preparation techniques, and dynamic mechanism analysis. Finally, future development directions were proposed, including the development of new materials, precise design of selective active sites, optimization of preparation processes, and promotion of interdisciplinary research. This review provides a systematic reference for the mechanism exploration and rational design of catalysts in electrocatalytic nitrite reduction technology and is expected to promote its practical application in green ammonia synthesis and environmental remediation.