Carbon fibers with cup-stacked-type structure: An advantageous support for Pt-Ru catalyst in methanol oxidation

Carbon fibers with dangling bonds lined up in an orderly way on the wall of the carbon tube and with an average tube diameter of about 25 nm were studied as support for Pt-Ru nanoparticles. These nanoparticles were prepared using a non-ionic water-in-oil microemulsion (w/o) formed by polyethylenglycol-dodecylether, n-heptane, and water. To evaluate the electrochemical performance of this novel catalyst, Pt-Ru nanoparticles supported on carbon Vulcan XC were also prepared by the microemulsion method for comparison. Transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray analysis, and nitrogen adsorption were used to investigate the carbon-supported Pt-Ru catalysts. The microemulsion method furnished Pt-50-Ru-50 particles with average particle sizes of 4.0 +/- 0.8 nm, for both carbon supports. The electrocatalytic activity of the supported alloys in methanol oxidation was investigated by cyclic voltammetry and chronoamperometry. Results reveal that the catalytic activity is enhanced by a factor of two when the carbon nanofibers are used as support for the Pt-Ru nanoparticles. The electronic conductivity of the carbon fibers and dangling bonds seem to be the factors responsible for the excellent performance exhibited by the electrodes. (c) 2006 Elsevier B.V. All rights reserved.