Tracing transport of dissolved electrocatalysts in proton exchange membrane water electrolysis using operando synchrotron X-ray fluorescence

To improve long-term stability of anodes in proton exchange membrane water electroysers (PEMWE), understanding the degradation of iridium-based electrocatalysts is of great interest. Previous results have shown that most of the dissolved catalyst redeposits in the membrane and the cathode catalyst layer (CCL), however, in-situ data for iridium dissolution is to the best of our knowledge only available for aqueous model systems (AMS) but not for full cells. By means of synchrotron-based operando small- and wide-angle X-ray spectroscopy (SAXS, WAXS), and X-ray fluorescence spectroscopy (XRF), we will shed light on the transport mechanism, i.e. diffusion and migration, of dissolved catalyst through the membrane towards the CCL in a single-cell PEMWE. Obtained results are the basis to model transport of dissolved catalyst and unravel discrepancies between full cell systems and AMS.