1 Inner Mongolia University, College of Chemistry and Chemical Engineering, College of Energy Material and Chemistry, Hohhot, 010021, Hohhot, CHINA.
2 Inner Mongolia University, College of Chemistry and Chemical Engineering, College of Energy Material and Chemistry, Inner Mongolia University South Campus, 010020, Hohhot, CHINA.
3 Concordia University, Department of Chemical and Materials Engineering, Montreal, QC H3G 2W1, Montreal, CANADA.
4 Inner Mongolia University, College of Chemistry and Chemical Engineering, College of Energy Material and Chemistry, Hohhot 010021, P. R. China., 010021, Hohhot, CHINA.
5 Inner Mongolia University, College of Chemistry and Chemical Engineering, Hohhot 010021, P. R. China., 010021, Hohhot, CHINA.

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 AuxCu single-atom alloy aerogels (AuxCu 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 VRHE). The FE of the catalyst was close to 100% at a high reduction potential of -0.8 VRHE, accompanying with NH3 yield reaching 6.21 mmol h-1 cm-2. More importantly, the catalyst maintained a long-term operation over 400 h at 400 mA cm-2 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.