Cationic-group Functionalized Electrocatalysts Enable Stable Acidic CO2 Electrolysis
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posted on 2023-08-23, 09:26 authored by Mengyang Fan, Jianan Erick Huang, Rui Kai Miao, Yu Mao, Pengfei Ou, Feng Li, Xiao-Yan Li, Yufei Cao, Zishuai Zhang, Jinqiang Zhang, Yu Yan, Adnan Ozden, Weiyan Ni, Ying Wang, Yong Zhao, Chen Zhu, Behrooz Khatir, Colin P O’Brien, Yi Xu, Yurou Celine Xiao, Geoffrey WaterhouseGeoffrey Waterhouse, Kevin Golovin, Ziyun WangZiyun Wang, Edward H. Sargent, David SintonAcidic electrochemical CO2 reduction (CO2R) addresses CO2 loss, and thus mitigates the energy penalties associated with CO2 recovery; however, acidic CO2R suffers low selectivity. One promising remedy – using a high concentration of alkali cations – steers CO2R towards multi-carbon (C2+) products; but these same alkali cations result in salt formation, limiting operating stability to <15 hours. Here we present cationic groups (CG) functionalized copper that enables efficient CO2 activation in a stable manner: by replacing alkali cations with immobilized benzimidazolium cationic groups within ionomer coatings, we achieve over 150 hours of stable CO2R. We find the water-management property of CG minimizes proton migration that enables operation at a modest voltage of 3.3 V with mildly alkaline local pH, leading to more energy-efficient CO2R with a C2+ Faradaic efficiency of 80%±3%. As a result, we report an energy efficiency of 28% for acidic CO2R towards C2+ products, and a single-pass CO2 conversion efficiency exceeding > 70%.
