The active facet of copper and its alloy for selective and efficient electrochemical reduction of nitrate to ammonia

Electrochemical reduction of nitrate (NO3-) to ammonia (NH3) (the e-NO3RR) is one of the most widely discussed methods to remediate the NO3- concentrations found in industrial and agricultural wastewater. The growing importance of NH3 stems from its central role in fertilizer and advanced chemical production and as an emerging renewable hydrogen carrier due to its excellent hydrogen ratio and liquefiability. This review highlights how the active facets of copper (Cu), the most widely documented electrocatalyst for e-NO3RR, and its alloys transform NO3- to NH3. The literature findings on Faradaic efficiency and the NH3 formation rate in connection with the Cu facet, Cu oxide, and Cu alloys are discussed, followed by a discussion of the potential opportunities of the eNO3RR. We hope this review will provide helpful information to facilitate the design of the next generation of electrocatalysts.