Identification\nof Degradation Reasons for a CO<sub>2</sub> MEA Electrolyzer Using\nthe Distribution of Relaxation Times\nAnalysis

The application of membrane electrode assembly (MEA)\nin electrocatalytic\nCO<sub>2</sub> reduction (ECO<sub>2</sub>R) technology is an essential\nstep toward industrialization. Nevertheless, the issue of ECO<sub>2</sub>R failure in MEA during extended operation hinders its industrial\napplication. In this work, we employed in situ, nondestructive electrochemical\nimpedance spectroscopy (EIS) techniques combined with distribution\nof relaxation times (DRT) methodology to diagnose the causes of the\nfailure. By systematically investigating the variations in polarization\nresistance throughout the degradation process and utilizing a controlled\nvariable approach to identify the origin of polarization, we diagnosed\nthe degeneration of ionomers as the primary cause of the performance\ndegradation of ECO<sub>2</sub>R in this instance. We further confirmed\nthe reliability of our findings through material characterization\nand respraying ionomers onto the catalyst surface. This research provides\nan effective diagnostic method for the failure analysis of ECO<sub>2</sub>R performance in MEA, which is crucial for advancing industrialization\nof ECO<sub>2</sub>R technology.