Proton exchange membrane fuel cell catalyst layers (CLs) have complex structures that largely determine their performance and durability. Their three-dimensional morphology and component spatial distribution is still poorly understood. This comprehensive work reports one of the first cryogenic transmission electron tomography reconstructions of a full commercial CL section, including challenging-to-image ionomer distribution.
The true component morphology and spatial three-dimensional (3D) distribution of these complex systems on a nanoscale is still poorly understood and not trivial to obtain with standard imaging or spectroscopy techniques. Transmission electron tomography offers an avenue to provide this important information. This is a technique where a series of transmission electron microscopy (TEM) images are acquired while a sample is rotated under a range of tilt angles (for example, from –70o to 70o; Fig. 1b). The acquired tomograms, consisting of images collected at the tilt angles, are reconstructed into 3D