Atomic Eu‐Mediated Acetonitrile Adsorption Configuration Switch Drives Long‐Term and Ampere‐Level Electrosynthesis of Ethylamine in AEM Electrolyzer

ABSTRACT Electrocatalytic hydrogenation of acetonitrile (AN‐ECH) offers a sustainable pathway for ethylamine (EA) synthesis. However, achieving high selectivity in AN‐ECH necessitates carefully balancing proton availability to suppress the hydrogen evolution reaction (HER), which often conflicts with the proton supply requirements under industrial‐grade current densities. Herein, we design and develop a novel and effective AN‐ECH catalyst consisting of rare‐earth Eu atoms modified on Cu ₂ O nanoneedles to drive efficient and durable AN‐ECH at ampere‐level currents. The optimized Eu‐Cu ₂ O catalyst achieves a high EA Faradaic efficiency of 98.1 % and an exceptional production rate of 2253.2 µmol h ⁻¹ cm ⁻² compared with pure Cu ₂ O. Notably, the Eu‐Cu ₂ O can continuously operate 420 h at 2 A in an anion‐exchange membrane electrolyzer for AN‐ECH, representing the longest reported stability under the industrial‐current conditions to date. Operando characterization and theoretical calculations elucidate that the Eu incorporation tailors the electronic structure of Cu sites, thus switching the adsorption configuration of AN from the flat‐lying multi‐site π‐adsorption to vertical N‐end adsorption. This reconfiguration of the adsorption site lowers the energy barrier for the imine hydrogenation step, dictating the ideal proton addition pathway while enhancing the proton addition kinetics to suppress the HER. This work provides fundamental insights into rare‐earth tuning of AN hydrogenation mechanisms and represents a critical advancement toward ampere‐scale electrosynthesis of EA.