From Flue Gas to Syngas: Composite Electrode Based on Ionic Liquid and Microporous Polymer for MEA‐Based CO₂ Electrolysis

Abstract

AbstractThe electrochemical CO2 reduction reaction (ECO2R) offers a promising pathway to convert CO2 into value‐added products. While catalyst advances remain crucial, gas‐diffusion electrodes (GDEs) architecture is equally vital in CO2 electrolyzer design. Most ECO2R studies use pure CO2 feeds, whereas industrial sources like flue gas contain ∼15% CO2, requiring costly purification. Eliminating this step demands electrolyzers that directly process impure streams via in situ separation. Here, we introduce a composite GDE (CGDE) featuring a thin CO2‐selective interlayer of intrinsically microporous polymer (PIM‐1) reinforced with the CO2‐philic ionic liquid [Emim][BF4]. This layer selectively adsorbs CO2 and suppresses N2/O2 existence at the catalyst interface. In simulated flue gas (15% CO2, 5% O2 in N2), the CGDE with 20 wt% [Emim][BF4]/PIM‐1 achieved >70% CO Faradaic efficiency (FE) at 100 mA cm−2, versus ∼20% FE for a pristine GDE. Multiphysics simulations confirmed effective CO2 delivery through the selective layer, with minimal O2 permeation. Cost estimation analysis indicates around 25% reduction in CO's minimum selling price using the integrated design and >50% under ideal performance metrics by eliminating compression/transport. These results demonstrate that advanced electrode design with CO2‐selective interlayer enables direct mixed‐gas ECO2R, establishes key design criteria for selective layers, and significantly improves process economics.