Engineering the Metal‐Support Interaction and Oxygen Vacancies on Ru@P‐Fe/Fe3O4 Nanorods for Synergetic Enhanced Electrocatalytic Nitrate‐to‐Ammonia Conversion

Abstract Ruthenium (Ru) loaded catalysts show high activity and selectivity for ammonia (NH 3 ) synthesis via electrochemical reduction of nitrate (NO 3 − ), but their practical application is still restricted by their high cost and insufficient stability. Herein, a multi‐component electrocatalyst of Ru nanoclusters loaded on phosphorus‐doped/phosphate‐modified and oxygen vacancy (O V )‐rich Fe/Fe 3 O 4 composite nanorods (Ru@P‐Fe/Fe 3 O 4 ) to synergistically promote electrocatalytic NO 3 − reduction reaction (NO 3 − RR)‐to‐NH 3 performance via strong metal‐support interaction (SMSI) is reported. Impressively, the best Ru@P‐Fe/Fe 3 O 4 catalyst exhibits outstanding NO 3 − RR activity, selectivity, and durability in 0.1 M KNO 3 + 0.5 M KOH solution, with an NH 3 yield rate of 14.37 ± 0.21 mg NH3 h −1 cm −2 (1710.71 ± 25 mg NH3 h −1 mg Ru −1 ) at −0.75 V versus reversible hydrogen electrode (vs. RHE), an NH 3 Faradaic efficiency (FE) of 97.2% at −0.55 V vs. RHE, and a superior stability over 50 h, suppressing most of reported Fe‐based and Ru‐based electrocatalysts. The characterizations and theoretical calculations unveil that the SMSI between Ru nanoclusters and P‐Fe/Fe 3 O 4 composite nanorods can promote the generation of O V , tune the electronic structure of Ru species, and stabilize Ru nanoclusters, thereby reducing the reaction energy barrier of NO 3 − RR‐to‐NH 3 , inhibiting the competitive hydrogen evolution reaction, and boosting the NH 3 yield rate NH 3 FE, and stability.