Identifying and alleviating the durability challenges in membrane-electrode-assembly devices for high-rate CO electrolysis

Abstract CO electrolysis (COE) has emerged as an important alternative technology to couple with other sustainable techniques for transitioning towards a carbon-neutral future. A large challenge for the deployment of high-rate COE is the limited durability of the membrane-electrode-assembly (MEA). In this work, by utilizing an operando wide-angle X-ray scattering (WAXS) technique and monitoring the change of electrolyte, we identified several degradation mechanisms of the MEA during high-rate COE. Cathodic gas diffusion electrode (GDE) flooding and metal contaminants (crossover from anode) are two major issues causing excessive HER, which can be partly alleviated by increasing the PTFE content in the GDEs and using an alkaline stable Ni-based anode. When analyzing MEA’s long-term stability, the dynamic evolution of anolyte became the major issue: the pH would continuously drop due to cathodic acetate formation and anodic ethanol oxidation. By compensating for this issue, we maintained a Faradaic Efficiency (FE) of C2+ products to be over 70% during a 136-h testing period. Our findings provide clear guidelines to circumvent the durability challenges for high-rate CO/CO2 electrolysis.