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

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.