Cationic-group-functionalized electrocatalysts enable stable acidic CO₂ electrolysis

MY Fan and JE Huang and RK Miao and Y Mao and PF Ou and F Li and XY Li and YF Cao and ZS Zhang and JQ Zhang and Y Yan and A Ozden and WY Ni and Y Wang and Y Zhao and Z Chen and B Khatir and CP O'Brien and Y Xu and YC Xiao and GIN Waterhouse and K Golovin and ZY Wang and EH Sargent and D Sinton, NATURE CATALYSIS, 6, 763-772 (2023).

DOI: 10.1038/s41929-023-01003-5

Acidic 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 h. Here we present a copper catalyst functionalized with cationic groups (CG) that enables efficient CO2 activation in a stable manner. By replacing alkali cations with immobilized benzimidazolium CG within ionomer coatings, we achieve over 150 h of stable CO2R in acid. 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%.

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