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

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 membrane-electrode assembly (MEA) devices. Here, by using an operando wide-angle X-ray scattering 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 Ir contaminants (crossover from anode) are two main issues causing excessive hydrogen evolution, which can be partly alleviated by increasing the polytetrafluoroethylene content in GDEs and using an alkaline stable Ni-based anode. During long-term stability, the dynamic evolution of anolyte became the main 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 of C₂₊ products at more than 70% for 136 hours. [Figure not available: see fulltext.]