Enhanced Nitrate-to-Ammonia Activity on Copper–Nickel Alloys via Tuning of Intermediate Adsorption

Abstract

Electrochemical conversion of nitrate (NO3–) into ammonia (NH3) recycles nitrogen and offers a route to the production of NH3, which is more valuable than dinitrogen gas. However, today’s development of NO3– electroreduction remains hindered by the lack of a mechanistic picture of how catalyst structure may be tuned to enhance catalytic activity. Here we demonstrate enhanced NO3– reduction reaction (NO3–RR) performance on Cu50Ni50 alloy catalysts, including a 0.12 V upshift in the half-wave potential and a 6-fold increase in activity compared to those obtained with pure Cu at 0 V vs reversible hydrogen electrode (RHE). Ni alloying enables tuning of the Cu d-band center and modulates the adsorption energies of intermediates such as *NO3–, *NO2, and *NH2. Using density functional theory calculations, we identify a NO3–RR-to-NH3 pathway and offer an adsorption energy–activity relationship for the CuNi alloy system. This correlation between catalyst electronic structure and NO3–RR activity offers a design platform for further development of NO3–RR catalysts.