(651e) Design, Preparation And Characterization Of Bimetallic/trimetallic Nanoparticle Catalysts

The understanding of the factors governing the preparation of bimetallic/trimetallic nanoparticles is important for the rational design and exploitation of the nanostructured catalysts for catalytic reactions. This presentation discusses recent findings of our investigations of the synthesis and processing protocols for the preparation of platinum- and gold-containing bimetallic and trimetallic nanoparticles on different support materials with controlled size, shape, composition, and surface properties. The synthesis strategy explores the manipulation of the metal precursor and the capping agent concentration ratios in the reaction solution, whereas the processing route explores thermally activated core-shell reactivities in a highly-concentrated solution of the nanoparticles. The bimetallic or trimetallic nanoparticles with controllable sizes (1-5 nm) and compositions (M1(n)M2(100-n), and M1(n)M2(m)M3(100-n-m)) were synthesized by molecularly-engineered reduction and decomposition reactions in solutions. Gold and alloy nanoparticles were investigated as model systems for developing the correlation of the core-shell reactivities with structural manipulation and processing control parameters. The resulting nanoparticles were supported on a variety of powder supports including carbon, silica, titanium oxide, and calcined by controlled thermal treatments. An array of techniques was used for the characterization of the nanoparticles, including x-ray diffraction, infrared spectroscopy, transmission electron microscopy?energy dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, and thermal analysis. The catalysts were examined in catalytic and electrocatalytic reactions, including methanol oxidation reaction and oxygen reduction reaction. The activity and stability of the electrocatalysts in fuel cell reactions were investigated by electrochemical techniques. The results will be discussed in terms of the synergistic properties of the bimetallic/trimetallic electrocatalysts for fuel cell and gas-phase reactions, providing the fundamental insights into the correlations between the nanocrystal phase and surface binding properties and between the size and composition of the nanoscale bimetallic or trimetallic catalysts.