Ampere-level current density ammonia electrochemical synthesis using CuCo nanosheets simulating nitrite reductase bifunctional nature.

The development of electrocatalysts capable of efficient reduction of nitrate (NO) to ammonia (NH) is drawing increasing interest for the sake of low carbon emission and environmental protection. Herein, we present a CuCo bimetallic catalyst able to imitate the bifunctional nature of copper-type nitrite reductase, which could easily remove NO via the collaboration of two active centers. Indeed, Co acts as an electron/proton donating center, while Cu facilitates NO adsorption/association. The bio-inspired CuCo nanosheet electrocatalyst delivers a 100 ± 1% Faradaic efficiency at an ampere-level current density of 1035 mA cm at -0.2 V vs. Reversible Hydrogen Electrode. The NH production rate reaches a high activity of 4.8 mmol cm h (960 mmol g h). A mechanistic study, using electrochemical in situ Fourier transform infrared spectroscopy and shell-isolated nanoparticle enhanced Raman spectroscopy, reveals a strong synergy between Cu and Co, with Co sites promoting the hydrogenation of NO to NH via adsorbed *H species. The well-modulated coverage of adsorbed *H and *NO led simultaneously to high NH selectivity and yield.