Boosting Electrocatalytic Nitrate Reduction to Ammonia on a Hierarchical Nanoporous Ag,Ni-Codoped Cu Catalyst via Trimetallic Synergistic and Nanopore Enrichment Effects.

Abstract

The electrochemical nitrate (NO₃^-) reduction reaction (NO₃^-RR) offers a promising route for NO₃^- wastewater treatment and sustainable ammonia (NH₃) synthesis. However, the reaction still faces the challenges of unsatisfactory productivity and selectivity. Herein, we report a hierarchical nanoporous Ag,Ni-codoped Cu (np Ag,Ni-Cu) catalyst that exhibits a high NH₃ Faradaic efficiency of 98.5% with an attractive NH₃ yield rate of 41.1 mg h^-1 mg_cat^-1 at -0.2 V vs RHE for the NO₃^-RR. Density functional theory calculations and molecular dynamics simulations suggest that the excellent performance of np Ag,Ni-Cu results from a trimetallic synergistic effect and nanopore enrichment/confinement effect, in which the codoping of Ni and Ag into Cu can enhance NO₃^- adsorption, prevent *NO₂ desorption, and suppress the hydrogen evolution reaction, while nanopores can promote NO₃^- accumulation on the internal surface of nanopores and confine the reaction intermediates within the nanopores for a deeper NO₃^- electroreduction.