Schulenburg, HendrikSchwanitz, BernhardLinse, NicolasScherer, Guenther G.Wokaun, A.Krbanjevic, JulijanaGrothausmann, RomanManke, Ingo2011-12-162011-12-162011-12-16201110.1021/jp203016uhttps://infoscience.epfl.ch/handle/20.500.14299/73810WOS:000292892500035During the lifetime of a polymer electrolyte fuel cell, the pore structure of the Pt/C catalyst layer may change as a result of carbon corrosion. Three-dimensional visualization of porosity changes is important to understand the origin of fuel cell performance deterioration. A focused ion beam/scanning electron microscopy (FIB/SEM) approach was adopted together with electron tomographic studies to visualize the three-dimensional pore structure of a Pt/C catalyst. In the case of pristine catalyst layers, the pores form an interconnected network. After 1000 start-up/shut-down cycles, severe carbon corrosion leads to a collapse of the support structure. The porosity of the degraded catalyst layer shrinks drastically, resulting in a structure of predominantly isolated pores. These porosity changes hinder the mass transport in the catalyst layer, consequently leading to a substantial loss of fuel cell performance. FIB/SEM serial sectioning and electron tomography allows three-dimensional imaging of the catalyst pore structure, which is a prerequisite for modeling and optimizing mass transport in catalyst layers.Carbon Corrosion3-Dimensional MicrostructureDegradationCathodeMicroscopyDamageAnodeVisualizationTomographyDurabilitytext::journal::journal article::research article