A Self‐Recycling Ruthenium Incorporated CuFe <sub>2</sub> O <sub>4</sub> Electrocatalyst for Efficient Neutral Ammonia Electrosynthesis
Yuning Wang, Wenyu Zhang, Yang Yang, Jinmeng Tong, Zhibo Liu, Tao Gan, Ali Han, Gang Liu
Abstract
Abstract The high performance of Fe‐based electrocatalyst for electrochemical nitrate reduction reaction to ammonia (eNO 3 − RR‐to‐NH 3 ) is currently constrained by low NH 3 selectivity and insufficient stability under high current density. Hence, the incorporation of ruthenium single‐atom into the CuFe 2 O 4 (Ru SA ‐CuFe 2 O 4 ) with self‐recycling property is developed. The Cu and Ru sites synergistically promote the water dissociation and facilitate the redeposition of in situ adsorbed Fe 2+ (Fe 2+ ad ) as α‐FeOOH by self‐reinforcing local alkalinity at the Ru SA ‐CuFe 2 O 4 surface, thereby achieving high activity and robust stability for eNO 3 − RR‐to‐NH 3 process. The optimized Ru SA ‐CuFe 2 O 4 delivers excellent performance with a 97.9% NH 3 Faradaic efficiency and 99.8% NH 3 selectivity at −0.59 V versus RHE in neutral electrolyte. Remarkably, in a membrane electrode assembly (MEA) system, it achieves a large current density of 1000 mA cm −2 at 2.5 V with robust stability, accompanied by >95% NH 3 selectivity, a nitrate removal rate of 4.17 mmol h −1 cm −2 , and an NH 3 production rate of 3.97 mmol h −1 cm −2 . Theoretical calculations have demonstrated that Ru site in the Ru SA ‐CuFe 2 O 4 significantly enhances NO 3 − adsorption and lowers the energy barrier for the potential determining step (*HNO 2 → *NO). This work offers valuable insights into designing autonomous local alkalinity microenvironments with self‐recycling properties on cost‐effective Cu/Fe oxides.