PdPt alloy nanoparticles (NPs) are promising catalysts for various chemical reactions because of the presence of powerful catalytic components of Pt and Pd on the surface of one nanostructure. In this paper, we report a facile synthesis of polyhedral PdPt alloy NPs via coreduction of Pd(acac) 2 (acac = acetylacetonate) and Pt(acac) 2 with morpholine borane in oleylamine at 90 and 180 °C. In the synthesis, the molar ratio of the two metal precursors added in the reaction mixture was carried over to the final PdPt NP product, and compositions of the PdPt NPs were readily tuned from Pd 88 Pt 12 to Pd 34 Pt 66 . These PdPt NPs show the composition-dependent catalytic activity for methanol oxidation, with NPs in 40À60 atomic % Pt exhibiting the superior activity and durability.

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Changes in a Au/TiO(2) catalyst during the activation process from an as-prepared state, consisting of supported AuO(x)(OH)(4-2x)(-) species, were monitored with X-ray absorption spectroscopy and FTIR spectroscopy, complemented with XPS, microcalorimetry, and TEM characterization. When the catalyst was activated with H(2) pulses at 298 K, there was an induction period when little changes were detected. This was followed by a period of increasing rate of reduction of Au(3+) to Au(0), before the reduction rate decreased until the sample was fully reduced. A similar trend in the activation process was observed if CO pulses at 273 K or a steady flow of CO at about 240 K was used to activate the sample. With both activation procedures, the CO oxidation activity of the catalyst at 195 K increased with the degree of reduction up to 70% reduction, and decreased slightly beyond 80% reduction. The results were consistent with metallic Au being necessary for catalytic activity.

A lloying a non-noble metal (M) with Pt has become a popular approach to Pt-based catalysts with much reduced Pt usage and enhanced Pt activity. 1À7 Depending on the chemical nature of M, PtM can be made highly active for either electrochemical oxidation or reduction. 5À8 Among various PtM alloys studied thus far, PtSn alloys represent an interesting group of catalysts not only for hydrogenation 9À11 and dehydrogenation reactions, 12À14 but also for electro-oxidation of carbon monoxide (CO), 15À20 methanol, 21À23 ethanol, 23À26 and ethylene glycol. 27 Previous evaluations on single crystals and thin films of Pt 3 Sn for catalytic CO oxidation suggest that Sn as an alloy component can enhance CO oxidation on Pt by promoting H 2 O dissociation on Sn to form SnÀOH and by altering electronic properties of Pt through its bonding with Pt, weakening the CO adsorption on Pt. 15À19 These experimental observations are further supported by the first-principles and density function theory calculations. 8,28 The activation energies for CO oxidation on Pt 3 Sn/Pt (111), Pt 3 Sn (111), and Pt (111) surfaces are 0.64 eV, 0.68, and 0.82 eV, respectively, 28 and water dissociation energy is lower on Sn (0.44 eV) than on Pt (0.67 eV). 8 These studies indicate that PtSn alloys in a nanoparticle (NP) form should be a more promising catalyst for CO and other small organic molecule oxidizations.In this paper, we report a high temperature organic phase synthesis of monodisperse Pt 3 Sn alloy NPs by coreduction of Pt and Sn salts and study their enhanced catalysis for CO and methanol oxidation reaction (MOR) in acid solutions. Previously, Pt 3 Sn NPs were synthesized directly on carbon supports from reduction of the absorbed Pt salt and Sn salt. 20 Recently, Pt 3 Sn NPs were prepared by room temperature H 2 reduction of Pt(dibenzylidene acetone) 2 with (n-Bu) 3 SnH, 29 or made by high temperature coreduction of Pt(acac) 2 (acac = acetylacetonate) and Sn(acac) 2 with 1,2-hexandecanediol. 21