Bimetallic Cu₁₁Ag₃ Nanotips for Ultrahigh Yield Rate of Nitrate-to-Ammonium

Electrochemical reduction of nitrate to ammonia (NRA) offers a sustainable approach for NH₃ production and NO₃ ^- removal but suffers from low NH₃ yield rate (<1.20 mmol h^-1 cm^-2). We present bimetallic Cu₁₁Ag₃ nanotips with tailored local environment, which achieve an ultrahigh NH₃ yield rate of 2.36 mmol h^-1 cm^-2 at a low applied potential of -0.33 V vs. RHE, a high Faradaic efficiency (FE) of 98.8 %, and long-term operation stability at 1800 mg-N L^-1 NO₃ ^-, outperforming most of the recently reported catalysts. At a NO₃ ^- concentration as low as 15 mg-N L^-1, it still delivers a high FE of 86.9 % and an NH₃ selectivity of 93.8 %. Finite-element method and density functional theory calculations reveal that the Cu₁₁Ag₃ exhibits reduced adsorption energy barrier of *N intermediates, favorable water dissociation for *H generation and high energy barrier for H₂ formation, while its tip-enhanced enrichment promoting NO₃ ^- accumulation.