Electrochemical Nitrate Reduction to Ammonia on AuCu Single‐Atom Alloy Aerogels under Wide Potential Window

Electrocatalytic nitrate reduction to ammonia (NO₃RR) is very attractive for nitrate removal and ammonia production in industrial processes. However, the nitrate reduction reaction is characterized by intense hydrogen competition at strong reduction potentials, which greatly limits the Faraday efficiency at strong reduction potentials. Herein, we reported an Au_xCu single-atom alloy aerogels (Au_xCu SAAs) with three-dimensional network structure with significant nitrate reduction performance of Faraday efficiency (FE) higher than 90 % over a wide potential range (0 ~ -1 V _RHE). The FE of the catalyst was close to 100 % at a high reduction potential of -0.8 V_RHE, accompanying with NH₃ yield reaching 6.21 mmol h¹ cm². More importantly, the catalyst maintained a long-term operation over 400 h at 400 mA cm² for the NO₃RR using a continuous flow system in a H-cell. Experimental and theoretical analysis demonstrate that the catalyst can lower the energy barrier for the hydrogenation reaction of *NO₂, leading to a rapid consumption of the generated *H, facilitate the hydrogenation process of NO₃RR, and inhibit the competitive HER at high overpotentials, which efficiently promotes the nitrate reduction reaction, especially in industrial applications.