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O: Fachverband Oberflächenphysik

O 73: Solid/liquid interfaces II (focussed session)

O 73.2: Hauptvortrag

Donnerstag, 25. März 2010, 15:30–16:00, H33

Investigations on Pt based catalysts for PEM fuel cells: from model systems to high surface area catalysts — •Matthias Arenz — Technische Universität München, Physikalische Chemie, Lichtenbergstr. 4, D-85748 München

The long term stability as well as the slow rate of the oxygen reduction reaction (ORR) are the main fundamental problems in the catalysis concerning polymer electrolyte membrane fuel cells. On Pt based model electrodes (single crystals and polycrystalline samples), it has recently been demonstrated how by fine-tuning the electronic structure of the surface, the specific activity for the oxygen reduction can be drastically enhanced. However, there is still a great challenge to create catalyst particles with the electronic and structural properties of the most active bulk crystal surfaces. For this task, the testing of high surface area catalysts, especially establishing the true specific activity of nanoparticle catalysts, is of highest importance. In the presentation the testing of high surface area catalysts by the so-called thin film rotating disc electrode method is critically discussed. It will be shown how reproducible activity measurements can be performed. In this respect it is demonstrated how the treatment of catalysts affects their surface composition and structure. Furthermore, a new TEM methodology for testing the stability of catalysts in accelerated ageing tests is introduced as well as new results on size selected Pt particles are shown.