Regensburg 2010 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 41: Nanoparticles and Composite Materials II
CPP 41.7: Talk
Thursday, March 25, 2010, 15:45–16:00, H48
Synthesis of stable bimetallic AuAg and CoPd colloids via diblock copolymer micelle nanoreactors — •Willian G. Menezes1, Volkmar Zielasek1, Christian Kübel2, Karsten Thiel3, and Marcus Bäumer1 — 1Universität Bremen, Institut für Angewandte und Physikalische Chemie — 2Forschungszentrum Karlsruhe / KIT — 3Fraunhofer IFAM, Bremen
The preparation of metal nanoparticles (NPs) by using block copolymers (BCP) as encapsulating agent yields NPs with narrow size distributions and outstanding control over the inter-particle distance. Various metal salts, also in combination, can be easily loaded as precursor for NPs into the micelle cores.[1] We will demonstrate the synthesis of AuAg and CoPd bimetallic NPs by using PS-b-P4VP as stabilizing agent and N2H4·H2O as reducing agent. TEM images show spherical crystalline NPs with diameters varying between 3 and 6 nm, for both, AuAg and CoPd. In UV-vis only one plasmon band at 460 nm was observed for Au-Ag NPs, indicating the formation of truly bimetallic NPs. STEM and EDX confirm that single NPs contain both metals, in the case of AuAg with atomic ratios of Au:Ag as 1:1, in agreement with the metal salt concentrations used. In catalysis, bimetallic systems can demonstrate unique properties distinct not only from the bulk metals but also from the corresponding monometallic NPs. The results of first catalytic tests for CO oxidation at titania loaded with AuAg and CoPd NPs prepared via the BCP route will be presented. Despite the organic matrix, the NPs are active for CO oxidation under certain conditions.
[1] S. Förster, M. Antonietti, Adv. Mater. 10 (1998) 195.