Carbon-supported Pt-Ru catalysts prepared by the Nafion stabilized alcohol-reduction method for application in direct methanol fuel cells

The Nation stabilized alcohol-reduction method has been used to prepare Pt-Ru. catalysts supported on Vulcan XC-72. The particle size and morphology of catalysts are determined by X-ray diffraction analysis and transmission electron microscopy. Well-dispersed catalysts with particle sizes from 3 to 7 nm are achieved. The catalytic activities of these catalysts towards methanol electro-oxidation are investigated at electrode potentials of interest for fuel cells. The addition of Nation during catalyst preparation enhances the methanol electro-oxidation activity even for low methanol concentrations. The in-house prepared Pt-Ru/C catalysts (MEC-01 and MEC-03) in 0.5 M H2SO4 with 5% methanol at 40degreesC display a higher catalytic activity than a standard Pt-Ru/C (E-TEK 40) catalyst. In 5% methanol, the impedance of the in-house catalyst is lower than that of the standard Pt-Ru/C (E-TEK 40) catalyst, viz., 26.18 mg Omega versus 139.49 mg Omega. The Structure of the in-house prepared MEC-01 catalyst is compared with that of commercial E-TEK 40 by means of X-ray absorption spectroscopy. The X-ray absorption near-edge (XANES) of the MEC-01 catalyst at Pt L-III-edge shows significant variation in white line intensity compared with that of the commercial E-TEK 40 catalyst. (C) 2004 Elsevier B.V. All rights reserved.