Gram-level NH₃ Electrosynthesis via NO_x reduction on a 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 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 Co sites and optimal structure, the target modified Co foam 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.