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Contribution of Transmission Electron Microscopy to Proton Exchange Membrane Fuel Cell Electrodes Development and Degradation Understanding

Proton exchange membrane fuel cell (PEMFC) is one of the most promising zero emission power sources. The membrane/electrode assembly (MEA) that constitutes the fuel cell core is composed of a proton conducting membrane coated on each side with catalyst layers where the electrochemical reactions take place. These electrodes exhibit a complex porous nanostructure consisting of carbon black supporting Pt nanoparticles, ensuring electronic conduction and electro-catalysis, and of ionomer for protons transport, also used as the binder. Significant progress made on MEA components was a key factor for the recent introduction of fuel cell vehicles in the market. However a widespread commercialisation still requires reductions in costs and improvement in performance and durability. Consequently further research is needed to continue MEA component optimization and to increase understanding of their degradation mechanisms. In these research domains, transmission electron microscopy (TEM) has become an essential tool.