Loosely Packed Catalyst Layers Promote Gas Transport and Flooding Resistance in Gas Diffusion Electrodes for Electrochemical CO 2 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 Cubased 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.