Structure, Properties, and Degradation of Ultrathin Ionomer Films in Catalytic Layers of Fuel Cells

Kurzfassung

The structure of electrodes for proton-exchange membrane fuel cells and electrolysers has an important impact on Performance and degradation. Ionomer films covering Pt/C agglomerates in fuel cell electrodes have a thickness in the range of 4 to 15 nm and differ from the bulk structure with their mostly lamellar films. The formation of such nanothin films deposited by drop-casting and self-assembly was studied by atomic force microscopy. For different equivalent weights and different solvents of Aquivion® and Nafion® dispersions, the size and structure of the Dispersion particles, of sub-monolayers, single and multilayers was investigated on graphene, platinum, mica, and silicon. The size of dispersion particles strongly depends on the solvent. On hydrophobic graphene, the height of ionomer bundles and layers measures 1.5 nm, significantly less than the 2.5 nm height found on hydrophilic Pt, Si, and mica.