Umicore Ag & Co Kg

De La Rue International Limited

Günther Vulpius

Ralf Zuber

Sandra Wittpahl

Peter Seipel

Klaus Schaack

Holger Dziallas

Götz Peter Hellmann

Peter Wolfgang Andreas Spahn

Bernd Dillmann

A method of forming a film of photonic crystal material. A first process is performed upon a material capable of having a photonic crystal structure, this process causing deformation of the material so as to form a film in which incident light received by the material is selectively reflected or transmitted to generate a first optical effect in the film. A second process is performed upon substantially all of the film which applies a shear stress to the film. This causes a change in the material structure so as to generate a second optical effect in the film, different from the first optical effect, in response to incident light. Security films, devices, articles and documents formed using the method are also discussed.

Method of forming a photonic crystal material

The invention relates to a membrane-electrode assembly (MEA) for electrochemical devices, in particular for membrane fuel cells. The membrane-electrode assembly has a semi-coextensive design and comprises an ion-conducting membrane, two catalyst layers and gas diffusion layers of differing sizes on the front side and rear side. The first gas diffusion layer has smaller planar dimensions than the ion-conducting membrane, while the second gas diffusion layer has essentially the same planar dimensions as the ion-conducting membrane. As a result, the ion-conducting membrane has a surface which is not supported by a gas diffusion layer on the front side. The membrane-electrode assembly has, owing to the particular construction, a stable structure which can be handled readily and displays advantages in the sealing of the reactive gases from one another and also in terms of the electrical properties. In particular, the hydrogen penetration current is significantly reduced. New processes for producing the MEA of the invention are described, in particular the method of heat pulse welding. The membrane-electrode assembly is used in PEM fuel cells, direct methanol fuel cells, electrolysers and other electrochemical devices.

Membrane electrode assembly for use in electrochemical devices

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Riedstadt, Germany

Günther Vulpius