Applikation Sample AFM

The key component of a Proton-Exchange Membrane (PEM) fuel cell is the membrane-electrode assembly (MEA). It consists of a solid state electrolyte, usually a film of Nafion®, a synthetic material, with electrodes mounted on both sides, in which the electro-chemical reactions take place. Investigating such catalytic membranes is a substantial part of the research work undertaken in the AFM Laboratory.

The illustration shows the topographical structure of such a membrane surface imaged with the AFM.

AFM methodology can provide a lot more information apart from the topology. This is demonstrated by the above AFM measurements on the surface of the catalytic layer:

Topography (a), adhesion (b), deformation (c), electric current (d), and diagram of the development of these material parameters along the path shown in red (e). The curves in (e) indicate low adhesion and deformation, as well as an electric current for the platinum and carbon catalyst particles. The AFM can thus measure the distribution of the ionomer in the electrodes on the basis of its characteristic mechanical, chemical and physical properties.

Using the AFM to measure a membrane cross-section utilises the material properties to provide detailed information on its structure close to the interface between the Nafion® membrane and the electrode.

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