Degradation location study of proton exchange membrane at open circuit operation

In order to investigate the location of the radical-initiated membrane degradation at open circuit operation, ceria (CeO2) nanoparticles are firstly placed at different locations of the membranes to scavenge free radicals generated there. Scanning electron microscopy (SEM) is used to characterize cross-sectional morphology of membrane before and after the open circuit voltage (OCV) test. OCV decay rate is used as an indicator of membrane degradation rate. Composite membranes with CeO2 nanoparticles facing anode or cathode show improved membrane durability than that of plain membrane in terms of OCV decay rate and cross-sectional morphology. CeO2–Nafion composite membrane with the same thickness is subsequently proposed and it obtains the best durability. It is concluded that the chemical degradation at open circuit operation occurs at both sides of anode and cathode.