Electrocatalytic reduction of nitrogen oxide species to ammonia

The nitrogen cycle is one of the most important biochemical cycles. However, the development of human society has led to a substantial release of nitrogen oxide species, both as ions (NO_x⁻) and gases (NO_x), into the environment, causing a considerable burden on the natural denitrification processes. Electrocatalytic reduction of NO_x⁻ and NO_x emerges as a promising approach to transform these waste products into valuable ammonia, thereby contributing to the restoration of the nitrogen cycle. This review provides a concise overview of recent advances in electrocatalytic NO_x⁻ and NO_x reduction to ammonia, including detailed reaction mechanisms, catalyst development strategies based on both theoretical and experimental results, and the design and selection of electrolytic cells. Furthermore, it highlights key challenges associated with scaling up the reaction from laboratory-scale to practical industrial-scale application and explores potential opportunities to upgrade this reaction.