Promoting CO<sub>2</sub> Electroreduction to Multi‐Carbon Products by Hydrophobicity‐Induced Electro‐Kinetic Retardation
Mengjiao Zhuansun, Yue Liu, Ruihu Lu, Fan Zeng, Zhanyou Xu, Ying Wang, Ying Wang, Yao‐Yue Yang, Ziyun Wang, Gengfeng Zheng, Yuhang Wang, Yuhang Wang
Abstract
Abstract Advancing the performance of the Cu‐catalyzed electrochemical CO 2 reduction reaction (CO 2 RR) is crucial for its practical applications. Still, the wettable pristine Cu surface often suffers from low exposure to CO 2 , reducing the Faradaic efficiencies (FEs) and current densities for multi‐carbon (C 2+ ) products. Recent studies have proposed that increasing surface availability for CO 2 by cation‐exchange ionomers can enhance the C 2+ product formation rates. However, due to the rapid formation and consumption of *CO, such promotion in reaction kinetics can shorten the residence of *CO whose adsorption determines C 2+ selectivity, and thus the resulting C 2+ FEs remain low. Herein, we discover that the electro‐kinetic retardation caused by the strong hydrophobicity of quaternary ammonium group‐functionalized polynorbornene ionomers can greatly prolong the *CO residence on Cu. This unconventional electro‐kinetic effect is demonstrated by the increased Tafel slopes and the decreased sensitivity of *CO coverage change to potentials. As a result, the strongly hydrophobic Cu electrodes exhibit C 2+ Faradaic efficiencies of ≈90 % at a partial current density of 223 mA cm −2 , more than twice of bare or hydrophilic Cu surfaces.