A comparative study between carbon supported Platinum-Tin (Pt-Sn-syn), synthesized via the carbonl route, and the commerical (Pt3Sn) from E-TEK is reported. The electro-oxidation of methanol and adsorbed CO, in sulphuric acid medium, were used as probes to evaluate the performance of these electrocatalysts. In-line differential mass spectrometry (DEMS) was used for this purpose. Both nanoparticulate materials had a mean particle size of < d > = 1.68 +/- 0.72 nm, and < d > = 3.58 +/- 1.98 nm, respectively. It is demonstrated that, under the same experimental conditions, our home-made Pt-Sn-syn is less sensitive to poisoning by CO. This observation was again verified during the oxidation of methanol. These results are discussed in terms of the local disorder of the particles surface atoms, favourably induced by size effect and the preparation route employed.

The electrochemical response and electrode potential-dependent infrared spectra for CO-adsorbate oxidation on unsupported ruthenium cluster-like material (Rux), prepared in two organic solvents: (xylene (Xyl), and 1,2-dichlorobenzene (Dcb)) from tris–ruthenium dodecacarbonyl decomposition, are reported. In spite of a similar particle size (2 nm) of the materials, the interfacial pseudo-capacitance of Rux(Xyl) is ca. four times higher than that of Rux(Dcb). Wide angle X-ray spectroscopy (WAXS) analysis on Rux(Xyl) and Rux(Dcb) nanoparticles revealed a high degree of structural disorder on Rux(Xyl) (J. Phys. Chem. B 105 (2001) 5238). The surface state of Rux(Xyl) and Rux(Dcb) used to oxidize CO, to form oxide-like (RuxOy) species, and used to recover the metallic nanoprecursor (under hydrogen annealing) can be inherently attributed to the degree of surface atom disorder. The CO absorption bands recorded on both types of surfaces are linear in nature and have apparently similar behavior to that observed on massive or well-defined ruthenium electrode surfaces.

Structural and stability studies of bimetallic Pt-Sn (3:1) nanoparticles were performed in situ via X-ray diffraction at wide angles (WAXS). The homemade bimetallic catalyst (Pt-Sn) ccomp (ecomp = from carbonyl complex) was synthesized in mild conditions from a Pt-carbonyl chemical precursor. A relatively narrow size distribution (2.4 +/- 0.9 nm) of such a bimetallic catalyst supported onto carbon Vulcan XC72 was obtained at room temperature. Its electrochemical behavior was compared to that of a commercial catalyst. The WAXS study revealed that such a catalyst, prepared via the carbonyl route, has a certain degree of surface disorder (high Debye parameter, B), which enhances the electrocatalytic activity for hydrogen adsorption. Furthermore, WAXS also demonstrated that the structural stability of this bimetallic catalyst is maintained at the annealing temperature employed (500 degreesC), although the particle size increases from 1.6 to 2.2 nm. Electrochemical underpotential deposition studies, via copper deposition, also provide information concerning the state of the nanoparticulate surface of the various platinum-based catalysts investigated.