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Carbon supported Au–Pt catalysts with different bimetallic compositions were prepared by water-in-oil (w/o) micro-emulsions. Carbon Vulcan XC-72R was added during the synthesis of particles in order to obtain good dispersion. Structural characterization was performed using XRD (X-ray diffraction) at wide angles, WAXS (wide-angle X-ray scattering) which showed that Pt–Au particles exhibited alloy properties in samples with high gold-content, and a segregation effect for those with low gold-content. Electrochemical characterization allowed estimation of the surface composition of Pt–Au alloys. These experiments have been confirmed by XRD data. Moreover, HRTEM (high resolution transmission electron microscopy) and XEDS (X-ray energy dispersive spectroscopy) characterization further confirmed the electrochemical results and XRD data. CO stripping experiments have shown an increasing bonding energy between CO and platinum with the gold content in the nanoalloys. [ABSTRACT FROM AUTHOR]

Abstract  Conducting polypyrrole (PPy)/C (Vulcan XC-72) composite materials were synthesized by chemical polymerization method. These materials were used as matrix to support platinum nanoparticles, which were produced by the carbonyl chemical route. For the same catalyst loading (50 μg cm−2), it was observed that the nature of the composite strongly influences the electrochemical activity of nanoparticulated platinum toward the oxygen reduction reaction in acid medium. The variation of the PPy/C ratio determines the so-called substrate effect for electrocatalysis. [ABSTRACT FROM AUTHOR]

The carbon monoxide molecule is used to probe the electronic properties of Ru/C and Se surface-modified Ru/C nanocatalysts. Coordination of a Se to a Ru surface strongly affects the vibrational properties and reactivity of the CO adsorbed. Marked alteration of the CO stretching frequency; increase of the Stark tuning rate for C–O vibration; and a positive shift of the onset of CO oxidation are observed for Se-modified Ru particles and attributed to the electronic effect of Se. [ABSTRACT FROM AUTHOR]