Methanol Electrochemistry at Carbon-Supported Pt and PtRu Fuel Cell Catalysts: Voltammetric and in Situ Infrared Spectroscopic Measurements at 23 and 60 °C

Abstract

The electrochemistry of methanol (50−200 mM) in 0.1 M HClO4 at Pt (10 wt %) and PtRu (30 wt % Pt, 15 wt % Ru) catalysts supported on Vulcan XC-72R carbon was investigated with voltammetry and in situ infrared spectroscopy at ambient temperature and 60 °C. The catalyst materials were each prepared as a thin film on a polished gold electrode according to a recently developed procedure [Weaver, M. J.; et al. J. Phys. Chem. B 2001, 105, 9719]. Methanol electrochemical oxidation was more sluggish on the Pt catalyst than on either bulk polycrystalline Pt or the PtRu catalyst material. The PtRu catalyst showed responses for methanol that were similar to those for a bulk PtRu alloy containing 46 wt % Ru. However, the PtRu catalyst appeared more resistant than bulk PtRu to CO adsorption. Differences are discussed in terms of the surface properties of bulk versus nanometer-scale Pt and PtRu.