Progress in selective electrochemical reduction of nitrate into ammonia

Abstract

Selective electrochemical reduction of nitrate (NO3-) into ammonia (NH_3) is critical for environmental remediation and resource recovery. This review comprehensively summarizes the recent advances in electrochemical conversion of NO3- into NH_3. Mechanisms of NO3- reduction are discussed. The conversion of NO3- into NO_2 and formation of N—H is the key for achieving high selectivity of NH3. The technologies and strategies for enhancing the performance of electrode are summarized and compared. The crystal structure, morphology and charge density of materials are the key factors affecting the properties of electrode materials. The influence of electrochemical reactor on NO3- conversion and NH_3 formation is described. The core of electrolytic cell is to avoid anode interference and in-situ realize NH_3 separation and recovery. With these facts, it is proposed that the strategies for NO3- electrochemical selective reduction synthesis of NH_3 are the development of low-cost, stable, and efficient electrode materials and electrochemical synthesis and in-situ separation of NH_3 reactor. Besides, the long-term large-scale research on the electrochemical synthesis of NH_3 from actual NO3- wastewater is critical for promoting the industrialization of this technology.

Keywords

• electrochemical reduction
• nitrate wastewater
• nitrate reduction
• selective reduction
• ammonia recovery