Morphological analysis of iridium oxide anode catalyst layers for proton exchange membrane water electrolysis using high-resolution imaging

This work demonstrates the application of high -resolution, 3D imaging to characterize micro- and nano -scale features of iridium oxide (IrO2) anode catalyst layers (CLs) in proton exchange membrane water electrolysis (PEMWE). Scanning electron microscopy (SEM) and nanoscale X-ray computed tomography (nano -CT) reveal differences in micro -scale features between spray -coated and blade -coated CLs, and in blade -coated CLs along the fabrication and testing timeline. The electrode thickness distribution of the tested blade -coated CL suggests increased thinning of regions compressed by titanium fibers of the porous transport layer (PTL). Ultrahigh -resolution imaging of Xe-plasma focused ion beam with SEM (pFIB-SEM) with the development of a segmentation method is used to investigate nano -scale features between these regions of the tested blade -coated CL, showing variations in porosity and pore sizes. The findings provide insights and modeling inputs for the morphology of PEMWE anode CLs towards a better understanding of the relationship between fabrication, operation, and transport behavior.