Permselective MOF-Based Gas Diffusion Electrode for Direct Conversion of CO<sub>2</sub> from Quasi Flue Gas
Tareq A. Al‐Attas, Shariful Kibria Nabil, Ali Shayesteh Zeraati, Hadi Shaker Shiran, Tartela Alkayyali, Mohammad Zargartalebi, Thien Tran, Nedal N. Marei, Md Abdullah Al Bari, Haiqing Lin, Soumyabrata Roy, Pulickel M. Ajayan, David Sinton, George K. H. Shimizu, Md Golam Kibria
Abstract
Industrial activities lead to a substantial share of current anthropogenic CO2 emissions and are some of the most challenging to abate. Direct utilization of industrial flue gases to produce fuels or value-added chemicals is challenging due to the presence of impurities and low concentrations of CO2. Herein, we demonstrate a rational assembly of a permselective gas diffusion electrode (PGDE) for direct CO2 conversion from quasi flue gas (i.e., 10–15% CO2, 4% O2, and N2 balance at 100% relative humidity). The electrode design consists of a metal–organic framework (MOF) based mixed matrix membrane (MMM) that enables the selective permeation of CO2 to a silver electrocatalyst. The MOF is CALF-20, notable for the ability to physisorb CO2 in wet gas streams. Applying this approach, we convert N2-diluted CO2 streams to CO at a faradaic efficiency of 95% compared to 58% for the nonmodified counterpart electrode with MMM. The PGDE retained its electrochemical performance when introducing O2 by preventing ∼84% loss of current toward parasitic oxygen reduction reaction (ORR) and reported 30 mA cm–2 CO partial current density. Further, wetting the gas stream showed a negligible effect on the MOF and the electrochemical performance. Using our PDGE, we report nearly constant CO selectivity over 19 h in a membrane electrode assembly electrolyzer. This approach offers the potential for direct utilization of low-concentration CO2 while avoiding the economic and environmental costs of obtaining purified CO2 feedstocks.