Dresden 2011 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 34: Nanomaterials I
MM 34.6: Vortrag
Donnerstag, 17. März 2011, 12:15–12:30, IFW B
Ultrasound-driven design of new mesoporous metal catalysts — Jana Schäferhans1, Ekaterina Skorb2, •Nicolas Pazos Perez1, and Daria Andreeva1 — 1Physikalische Chemie II, Uni Bayreuth, Deutschland — 2Max-Planck-Institut für Kolloid- und Grenzflächenforschung, Golm, Deutschland
Mesoporous metal nanocomposites were formed by a “green chemistry” method with ultrasound irradiation. The sonication technique combines the fabrication of a mesoporous support consisting of metallic particles (Al, Mg) several tens of micrometers in size and the subsequent incorporation of metal (Ag, Au, Pt etc.) nanoparticles into its pores. Next to filling the mesoporous support with particles we are also able to form mesoporous alloys e.g. AlNi or CoAlFe. The resulting material is analyzed by transmission electron microscopy, powder X-ray diffraction, small-angle neutron scattering and the Brunauer-Emmett-Teller and the Barrett-Joyner-Halenda method. Surface areas up to 200 m2/g with a narrow pore size distribution around 3 nm can be achieved. The mesoporous structures are analyzed by confocal light microscopy after coloring the particles with dye. We explain the formation of the mesoporous inner structures by the following mechanism: Thermal etching and recrystallization of metals by ultrasound-stimulated high-speed jets of liquid form the porous structure that is stabilized by surface oxidation through free radicals generated during cavitation. We expect this approach to be universal and opening perspectives for a whole new class of catalytic materials that can be prepared in a fairly easy and cost effective way.