Single Ag atoms induce Ag‐N/O bonds on WO3 for ultrastable acid ammonia synthesis

Ammonia from nitrate‐containing wastewater demands the catalysts with high activity, stability, and selectivity toward acidic electrochemical nitrate reduction owing to the corrosion effect of the catalyst and competitive hydrogen evolution reaction (HER). Herein, we synthesized single Ag atoms induced Ag‐N/O bonds on one‐dimensional WO3 nanowires for highly efficient and stable electrochemical nitrate reduction to ammonia under acidic conditions. The catalyst achieved a Faradaic efficiency (FE) of ammonia exceeds ~90% over a wide potential range of −0.6 ~ −0.2 VRHE with a maximum FE of approaching 100% at −0.4 VRHE and a maximum NH3 yield reaching 5.24 ± 0.41 mmol h−1 cm−2 at −0.55 VRHE. The catalyst maintained a current density at 480 mA cm−2 over 1100 h with a stable FE of ~94%. By integrating the catalyst into a membrane electrode assembly, we succeeded in obtaining a NH3 production rate of 104.08 mmol h‐1 at −3.5 V, and maintained the stability toward NO3RR for over 30 h with FE > 90%. Experimental and theoretical analysis demonstrate that the formation of Ag‐N/O bonds enhanced nitrate adsorption and lowered the energy barrier for the rate‐determining step of *NO→*NHO, considerably improving the efficiency of ammonia synthesis and inhibiting HER at amperometric current densities.