Web Release Date: January 23,
Bifunctional Electrocatalysis in Pt-Ru Nanoparticle Systems
and
Centre for Nanoscale Science, Department of Chemistry, The University of Liverpool, Liverpool, L69 7ZD, United Kingdom, Institute for Materials Science, TU Darmstadt, D-64287 Darmstadt, Germany, and Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
Received June 1, 2007
In Final Form: October 4, 2007
Abstract:
Pt-Ru alloys are prominent electrocatalysts in fuel cell anodes as they feature a very high activity for the oxidation of reformate and methanol. The improved CO tolerance of these alloys has been discussed in relation to the so-called ligand and bifunctional mechanisms. Although these effects have been known for many years, they are still not completely understood. A new approach that bridges the gap between single crystals and practical catalysts is presented in this paper. Nanoparticulate model systems attached to an oxidized glassy carbon electrode were prepared by combining both ligand-stabilized and spontaneously deposited Pt and Ru nanoparticles. These electrodes showed very different voltammetric responses for CO and methanol oxidation. The cyclic voltammograms were deconvoluted into contributions attributed to Pt, Ru, and Pt-Ru contact regions to quantify the contribution of the latter to the bifunctional mechanism. Scanning transmission electron microscopy confirmed the proximity of Pt and Ru nanoparticles in the different samples.
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