Gas diffusion electrodes, membrane-electrode assemblies and method for the production thereof
A gas diffusion electrode comprising an electrically conductive web, a non-catalyzed gas diffusion layer comprising at least one electroconductive filler and at least one binder, and a noble metal coating obtained by subjecting an electrically conductive web to a first ion beam having an energy not higher than 500 eV, then to a second beam having an energy of at least 500 eV, containing the ions of at least one noble metal.
1. A gas diffusion electrode, substantially free of ionomeric components, comprising (i) in an electrically conductive web, (ii) a non-catalyzed gas diffusion layer comprising at least one electroconductive filler and at least one binder, and (iii) a noble metal coating obtained by subjecting the electrically conductive web to a first ion beam having an energy not higher that 500 eV, and then to a second beam having an energy of at least 500 eV, said second ion beam containing the ions of at least one noble metal.
2. The gas diffusion electrode of claim 1 wherein the electrically conductive web is a metal or carbon cloth or a carbon paper.
3. The gas diffusion electrode of claim 1 wherein said at least one electroconductive filler comprises carbon particles, optionally acetylene black carbon particles.
4. The gas diffusion electrode of claim 1 wherein said at least one binder is hydrophobic and optionally fluorinated.
5. The gas diffusion electrode of claim 1 wherein said gas diffusion layer has a smoothness of at least 1000 Gurley seconds.
6. A membrane-electrode assembly comprising at least one gas diffusion electrode of claim 1 and an ion-exchange membrane.
7. The membrane-electrode assembly of claim 6 wherein said at least one gas diffusion electrode and said ion-exchange membrane are mutually bonded by hot pressing.
8. The membrane-electrode assembly of claim 6 wherein said ion-exchange membrane is not fluorinated, and wherein no ionomeric fluorinated component is present.