Immobilized Tetraalkylammonium Cations Enable Metal‐free CO2 Electroreduction in Acid and Pure Water

• Published in: Angewandte Chemie International Edition Vol. 63; no. 9; pp. e202317828 - n/a
• Main Authors: Fan, Jia, Pan, Binbin, Wu, Jialing, Shao, Chaochen, Wen, Zhaoyu, Yan, Yuchen, Wang, Yuhang, Li, Yanguang
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 26.02.2024
• Edition: International ed. in English
• Subjects: Acidic Condition; Alkali metals; Carbon dioxide; Carbon Efficiency; Catalysts; Cations; Chemical reduction; CO2 Electroreduction; Commercialization; Electrodes; Electrostatic properties; Energy costs; Energy efficiency; Graphene; Immobilized Cations; Membrane Electrode Assembly; Metal ions; Performance measurement; Polyelectrolytes
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202317828

Carbon dioxide reduction reaction (CO2RR) provides an efficient pathway to convert CO2 into desirable products, yet its commercialization is greatly hindered by the huge energy cost due to CO2 loss and regeneration. Performing CO2RR under acidic conditions containing alkali cations can potentially address the issue, but still causes (bi)carbonate deposition at high current densities, compromising product Faradaic efficiencies (FEs) in present‐day acid‐fed membrane electrode assemblies. Herein, we present a strategy using a positively charged polyelectrolyte—poly(diallyldimethylammonium) immobilized on graphene oxide via electrostatic interactions to displace alkali cations. This enables a FE of 85 %, a carbon efficiency of 93 %, and an energy efficiency (EE) of 35 % for CO at 100 mA cm−2 on modified Ag catalysts in acid. In a pure‐water‐fed reactor, we obtained a 78 % CO FE with a 30 % EE at 100 mA cm−2 at 40 °C. All the performance metrics are comparable to or even exceed those attained in the presence of alkali metal cations. A positively charged polyelectrolyte formed by the electrostatic interaction between poly(diallydimethylammonium)and graphene oxide is devised on the surface of Ag catalysts. This porous medium with immobilized cations augments CO2 electroreduction to CO in acid‐ and pure‐water‐fed zero‐gap electrolyzers.