Optimizing Intermediate Adsorption via Heteroatom Ensemble Effect over RuFe Bimetallic Alloy for Enhanced Nitrate Electroreduction to Ammonia

The electrochemical nitrate reduction reaction (NO3RR) is a promising approach for nitrate removal and NH3 synthesis at ambient conditions. As a complex eight-electron/nine-proton transfer process, its performance relies heavily on the adsorption ability of reaction intermediates on the catalyst surface, which is determined by the geometric and electronic configurations of active sites. In this work, a heteroatom ensemble effect is deliberately triggered over RuFe bimetallic alloy to optimize intermediate adsorption for NO3RR. A record-high NH3 yield rate of 118.8 mg h(-1) mg(-1) and a high Faradaic efficiency of 92.2% are achieved at -1.4 V vs reversible hydrogen electrode, ranking at the top of the state-of-the-art. Experimental and computational results reveal that the geometric and electronic characteristics of the induced heteroatom ensemble effect play crucial roles. Both Ru and Fe display a continuous state throughout the Fermi level, suggesting high electron density benefits the whole NO3RR. As a result, facilitated adsorption of NO3-, efficient stabilization of key intermediates, as well as the timely desorption of NH3 are simultaneously achieved, thus significantly promoting the direct reduction of NO3- to NH3.