Boosting Electrocatalytic Nitrate Reduction to Ammonia via Promoting Water Dissociation

Electrocatalytic nitrate reduction reaction (NO3–RR) opens opportunities for ammonia production. The sluggish kinetics of this multielectron and multiproton process has been 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 cm–2) and Faradaic efficiency (96.2%) for NH3 production at 0.075 V vs RHE, with a half-cell energy efficiency of 44.9%, higher than those of Cu, Co, and other Co-based alloys, and is among the highest value reported. We found that the interaction between Cu and Co reorganizes their electronic structure in alloys. The NO3– adsorption switches to a spontaneous process, and the *NO → *N and *NH → *NH2 processes are promoted. Importantly, the water dissociation process concerted with the transformation of N-species is proven to be rate-determining, which 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 for NO3–RR under alkaline condition by promoting the H2O dissociation process.