Cu–Fe Synergistic Active Sites Boost Kinetics of Electrochemical Nitrate Reduction

Abstract Electrochemical conversion of nitrate offers an efficient solution to nitrate pollution and a sustainable strategy for ammonia generation. Cu and Fe bimetallic electrocatalysts exhibit excellent electrochemical reduction of nitrate (NO 3 RR) reactivity but the conventional preparation strategy is complex and time‐consuming and this reaction is still suffers from unsatisfied kinetic and unidentified mechanisms. Herein, in situ electrodeposition strategy is employed to induce Cu to modify the Fe active sites of iron‐based N‐doping carbon nanofiber electrode (Fe/Fe 3 C@NCNFs) during NO 3 RR in Cu‐contained nitrate solution. Benefiting from the synergistic effect between Cu and Fe sites of Cu─Fe/Fe 3 C@NCNFs electrode, superior activity of rate‐determining reaction (*NO 3 to *NO 2 ) and reduced energy barriers of the following deoxidation and hydrogenation steps are achieved. Compared with Fe/Fe 3 C@NCNFs‐500, the pseudo‐first‐order (PFO) rate constant for NO 3 RR by Cu─Fe/Fe 3 C@NCNFs demonstrates nearly two‐fold improvement with high current efficiencies over wide pH and voltage range. Furthermore, the maximum NO 3 ─N removal capacity and N 2 selectivity of Cu─Fe/Fe 3 C@NCNFs reach 15593.8 mg N g −1 Fe and ca. 92% after twenty cycles. This work offers an avenue for highly active bimetallic electrode design, paving more insights into the interactions between active site construction and NO 3 RR performance.