Cu Nanowires Encapsulated by ZIF67 for Efficient Ammonia Electrosynthesis from Nitrate

Electrochemical NO₃ ^- reduction reaction (NO₃RR) represents a green and sustainable way to produce valuable NH₃ for both NH₃ production and nitrate contaminant removal, and developing efficient, durable, highly selective catalyst is the key. Herein, we report a facile method to fabricate a catalyst composed of ultrafine Cu nanowires (Cu NWs) encapsulated by ZIF67, namely, CuNW@ZIF67, for efficient NH₃ electrosynthesis from nitrate. The CuNW@ZIF67 catalyst exhibited excellent catalytic performance toward NO₃RR in alkaline electrolyte, manifested by a large NH₃ Faradaic efficiency of 93.7 % at -0.5 V versus reversible hydrogen electrode (RHE), a high energy efficiency over 30 % at -0.7 V, and robust long-term stability. Such intriguing catalytic properties are mainly ascribed to its structural merits and the strong electronic interaction between Cu NWs and ZIF67. DFT calculations revealed that, the Cu site can easily convert NO₃ ^- into NO₂ ^-, while the Co site plays a critical role in catalyzing the NO₂ ^--to-NH₃ process. The study can shed light on rational design of efficient, durable, and highly selective catalysts for NO₃RR and beyond.