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

Abstract

The Nafion 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 Nafion 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 H 2SO 4 with 5% methanol at 40 °C 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 Ω versus 139.49 mg Ω. 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 structure (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.