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

AbstractRuthenium (Ru) loaded catalysts show high activity and selectivity for ammonia (NH3) synthesis via electrochemical reduction of nitrate (NO3−), 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 (OV)‐rich Fe/Fe3O4 composite nanorods (Ru@P‐Fe/Fe3O4) to synergistically promote electrocatalytic NO3− reduction reaction (NO3−RR)‐to‐NH3 performance via strong metal‐support interaction (SMSI) is reported. Impressively, the best Ru@P‐Fe/Fe3O4 catalyst exhibits outstanding NO3−RR activity, selectivity, and durability in 0.1 M KNO3 + 0.5 M KOH solution, with an NH3 yield rate of 14.37 ± 0.21 mgNH3 h−1 cm−2 (1710.71 ± 25 mgNH3 h−1 mgRu−1) at −0.75 V versus reversible hydrogen electrode (vs. RHE), an NH3 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/Fe3O4 composite nanorods can promote the generation of OV, tune the electronic structure of Ru species, and stabilize Ru nanoclusters, thereby reducing the reaction energy barrier of NO3−RR‐to‐NH3, inhibiting the competitive hydrogen evolution reaction, and boosting the NH3 yield rate NH3 FE, and stability.