Permselective MOF-Based Gas Diffusion Electrode for Direct Conversion of CO₂ from Quasi Flue Gas

Abstract

Industrial activities lead to a substantial share of current anthropogenic CO 2 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 CO 2 . Herein, we demonstrate a rational assembly of a permselective gas diffusion electrode (PGDE) for direct CO 2 conversion from quasi flue gas (i.e., 10−15% CO 2 , 4% O 2 , and N 2 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 CO 2 to a silver electrocatalyst. The MOF is CALF-20, notable for the ability to physisorb CO 2 in wet gas streams. Applying this approach, we convert N 2 -diluted CO 2 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 O 2 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 CO 2 while avoiding the economic and environmental costs of obtaining purified CO 2 feedstocks.

Recent Progress and Outlook of Metal–Organic Framework Materials Used for CO2 Electrocatalytic Reduction

“…At the same time, the application of MOF composites in the field of photocatalytic carbon dioxide conversion has also attracted much attention. For example, some researchers have successfully applied ZIF-8/UiO-66-NH 2 /MoS 2 composites to the reaction of photocatalytic reduction of carbon dioxide to ethanol. ,− …”

Microscopic insight into the shaping of MOFs and its impact on CO2 capture performance

“…This MOF made of 1,2,4-triazolate bridged zinc( ii ) layers pillared by oxalate ions has been demonstrated recently as a benchmark CO 2 selective sorbent owing to its exceptionally high CO 2 /N 2 selectivity and large CO 2 uptake under working conditions. 39,40 The shaping of this highly chemically stable and easily scalable MOF has been achieved with the use of a single binder, i.e. , polysulfone; however, there is an associated loss of CO 2 sorption capacity as compared to its powdered form (about 20% loss).…”

Bifunctional Gas Diffusion Electrode Enables In Situ Separation and Conversion of CO2 to Ethylene from Dilute Stream

“…Addressing this supply constraint or direct intake of dilute CO 2 streams (≈10%) via in situ eCO 2 R could further lower the economic barrier to widespread utilization. [27] Recent reports on either ICCC or low-concentration CO 2 utilization employing eCO 2 R feature aqueous amine or alkali metal hydroxide based solvents for chemical absorption of CO 2 . [28][29][30] Amine or alkali scrubbing, the current benchmark for commercial carbon capture technology, suffers from cost and energy penalties associated with absorbent regeneration and regenerative amine losses.…”

“…Addressing this supply constraint or direct intake of dilute CO 2 streams (≈10%) via in situ eCO 2 R could further lower the economic barrier to widespread utilization. [ 27 ]…”