Synergistic Regulation of Intermediate Conversion and Activated Hydrogen Supply on Fe-Ru Diatomic Sites Drives Efficient Electroreduction of Neutral Nitrate to Ammonia

Abstract

Electrochemical conversion of nitrate (NO3−) represents an efficient strategy for mitigating NO3− pollutants while offering a promising alternative route for sustainable ammonia (NH3) synthesis. However, this process is hindered by the kinetic mismatch among initial NO3− adsorption, active hydrogen (*H) formation via water dissociation, and subsequent stepwise hydrogenation. Herein, an Fe-Ru diatomic catalyst (FeRuSA NC) was designed and synthesized, and it delivers a remarkable NH3 yield rate of 1.99 mmol h−1 mgcat.−1 and a high Faradaic efficiency (FE) of 96.8% at −1.2 V vs. RHE. The Fe-Ru diatomic sites reduce the energy barriers of the initial adsorption and the subsequent rate-determining hydrogenation step, thereby facilitating the reduction of NO3⁻ to NO2− and subsequent hydrogenation to NH3. Moreover, the Fe-Ru diatomic sites promote water dissociation via modulating the interfacial water structure (enriched K-H2O) and suppress HER, thus supply sufficient *H for deep hydrogenation of nitrogenous intermediates. This work unveils interactions between diatomic sites and multiple reactants/intermediates, providing new insights into the rational design of atomically dispersed catalysts for efficient NO3− reduction and NH3 synthesis.