Cu Nanowires Encapsulated by ZIF67 for Efficient Ammonia Electrosynthesis from Nitrate

Abstract Electrochemical NO 3 − reduction reaction (NO 3 RR) represents a green and sustainable way to produce valuable NH 3 for both NH 3 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 NH 3 electrosynthesis from nitrate. The CuNW@ZIF67 catalyst exhibited excellent catalytic performance toward NO 3 RR in alkaline electrolyte, manifested by a large NH 3 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 NO 3 − into NO 2 − , while the Co site plays a critical role in catalyzing the NO 2 − ‐to‐NH 3 process. The study can shed light on rational design of efficient, durable, and highly selective catalysts for NO 3 RR and beyond.