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

Abstract

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 and tip-enhanced effects, 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 Faradic 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%. Operando ATR-FTIR spectra, finite-element method, and DFT 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.