Loosely packed catalyst layers promote gas transport and flooding resistance in gas diffusion electrodes for electrochemical CO2 reduction

Abstract

Acidic CO₂ electrolysis enables high CO₂ utilization through carbonate protonation and high C₂₊ selectivity due to the elevated local alkalinity, yet its lifetime remains limited by gas diffusion electrode flooding. In this study, we reveal that a loosely packed, house-of-cards structure can be obtained by incorporating 2D-structured graphene nanoplatelets (GNPs) with Cu-based catalysts, effectively mitigating flooding. With an optimal GNP content below 9 wt%, this structure enhances CO₂ diffusion and significantly improves electrode lifetime, reaching 10 hours at a high current density of 600 mA cm⁻². Excessive GNP content leads to catalyst layer densification and accelerates flooding, highlighting the importance of a structure sufficiently thick to accommodate liquid seepage but also sufficiently porous to allow CO₂ access throughout the entire thickness. Our findings provide insights into a practical microstructural strategy for developing efficient and stable CO₂ electrolysis systems.