Gram-level NH3 Electrosynthesis via NOx reduction on Cu Activated Co Electrode.

Ambient electrochemical ammonia (NH3) synthesis is one promising alternative to the energy-intensive Haber-Bosch route. However, the industrial requirement for the electrochemical NH3 production with amperes current densities or gram-level NH3 yield remains a grand challenge. Herein, we report the high-rate NH3 production via NO3- and NO2- reduction using the Cu activated Co electrode in a bipolar membrane (BPM) assemble electrolyser, wherein BPM maintains the ion balance and the liquid level of electrolyte. Benefited from the abundant activated Co sites and optimal structure, the target CuCo electrode delivers a current density of 2.64 A cm-2 with the Faradaic efficiency of 96.45% and the high NH3 yield rate of 279.44 mg h-1 cm-2 in H-type cell using alkaline electrolyte. Combined with in-situ experiments and theoretical calculations, we found that Cu optimizes the adsorption behavior of NO2- and facilitates the hydrogenation steps on Co sites toward a rapid NO2- reduction process. Importantly, this activated Co electrode affords a large NH3 production up to 4.11 g h-1 in a homemade reactor, highlighting its large-scale practical feasibility.