Atomic Scale Cooperativity of Alloy Nanostructures for Efficient Nitrate Electroreduction to Ammonia in Neutral Media

Abstract Electrochemical nitrate reduction reaction (NO 3 RR) offers a route to balanced nitrogen cycle and sustainable ammonia production. However, unsatisfied performance in neutral media arising from competitive hydrogen evolution reaction and inefficient hydrogenation impede the further applications of NO 3 RR. Herein, the rational design of RuNi alloy nanostructures is reported. Benefited from the synergism effect between Ru and Ni, Ru 20 Ni 80 alloy exhibits a high NH 3 Faradaic efficiency of 98.02% at −0.35 V (vs reversible hydrogen electrode (RHE)) and a large NH 3 yield rate of 27.88 mg mg cat −1 h −1 at −0.65 V (vs RHE). Importantly, the atomic scale cooperation between Ru and Ni active sites endows RuNi alloy a close‐to‐unity NH 3 selectivity via HNO * pathway. Theoretical calculations have revealed that the interactions between Ru and Ni optimize the electronic structures of Ru 20 Ni 80 alloy, where Ru sites with enhanced electroactivity improve the generation of active hydrogens and more electron‐rich Ni sites facilitate the reduction of nitrate. Accordingly, the adsorption strengths of key intermediates become stronger and the energy barriers of NO 3 RR are reduced to guarantee efficient NO 3 RR. Furthermore, a flow‐type reactor coupled with coprecipitation is established to achieve continuous NH 3 generation and recovery as struvite.