Sustainable ammonia synthesis: opportunities for electrocatalytic nitrate reduction

Ammonia is the cornerstone of modern agriculture, providing a critical nitrogen source for global food production and serving as a key raw material for numerous industrial chemicals. Electrocatalytic nitrate reduction, as an environmentally friendly method for synthesizing ammonia, not only mitigates the reliance on current ammonia synthesis processes fed by traditional fossil fuels but also effectively reduces nitrate pollution resulting from agricultural and industrial activities. This review explores the fundamental principles of electrocatalytic nitrate reduction, focusing on the key steps of electron transfer and ammonia formation. Additionally, it summarizes the critical factors influencing the performance and selectivity of the reaction, including the properties of the electrolyte, operating voltage, electrode materials, and design of the electrolytic cell. Further discussion of recent advances in electrocatalysts, including pure metal catalysts, metal oxide catalysts, non-metallic catalysts, and composite catalysts, highlights their significant roles in enhancing both the efficiency and selectivity of electrocatalytic nitrate to ammonia (NRA) reactions. Critical challenges for the industrial NRA trials and further outlooks are outlined to propel this strategy toward real-world applications. Overall, the review provides an in-depth overview and comprehensive understanding of electrocatalytic NRA technology, thereby promoting further advancements and innovations in this domain.