Proton exchange membrane fuel cell (PEMFC) technology has advanced substantially in recent years, however durability challenges remain prominent, particularly for applications in heavy-duty trucking. Understanding mechanisms of membrane degradation in PEMFC membrane electrode assemblies (MEAs) is essential to identify opportunities for improvement. The key for PEMFC membrane degradation is by tracking cerium (Ce) loss via ex-situ or operando methods in response to chemical and/or mechanical stressors. In this work, we tested a set of commercial as well as recently developed MEA following specified stress accelerated testing (AST) and highly stress accelerated testing (HAST). we employed electron microprobe analysis (EPMA) to map Ce, Pt, F, and S elemental distributions within the MEA before and after AST and HAST testing. Membrane thinning in all cases was determined by scanning electron microscope (SEM) imaging. To ensure no Ce convolution with ther elements, we carried out high resolution x-rays photoelectron microscopy (XPS) on both anode and cathode surfaces. The oxidation state of Ce before and after testing was determined following synchrotron-based X-ray absorption spectroscopy (XAS) ex-situ measurements.
