Boosting Electrocatalytic\nNitrate Reduction to Ammonia\nvia Promoting Water Dissociation

Abstract

Electrocatalytic nitrate reduction reaction (NO₃^–RR) opens opportunities for ammonia production.\nThe\nsluggish kinetics of this multielectron and multiproton process has\nbeen regarded as the key issue. Herein, we report a Cu₁Co₅ alloy for electrocatalytic NO₃^–RR to NH₃. It achieves a high current density (453 mA\ncm^–2) and Faradaic efficiency (96.2%) for NH₃ production at 0.075 V vs RHE, with a half-cell energy efficiency\nof 44.9%, higher than those of Cu, Co, and other Co-based alloys,\nand is among the highest value reported. We found that the interaction\nbetween Cu and Co reorganizes their electronic structure in alloys.\nThe NO₃^– adsorption switches to a spontaneous\nprocess, and the *NO → *N and *NH → *NH₂ processes\nare promoted. Importantly, the water dissociation process concerted\nwith the transformation of N-species is proven to be rate-determining,\nwhich is facilitated on Co sites in the Cu₁Co₅ alloy and is essential for the enhanced NO₃^–RR. This inspires us a strategy for designing more efficient catalysts\nfor NO₃^–RR under alkaline condition by\npromoting the H₂O dissociation process.