Carbon nanofibers supported Pt-Ru electrocatalysts for direct methanol fuel cells

Oxidized and reduced carbon nanofibers (OCNF and RCNF) were used as supports to prepare highly dispersed PtRu catalysts for the direct methanol fuel cells (DMFC). The structural and surface features and electrocatalytic properties of bimetallic PtRu/ OCNF and PtRu/RCNF were extensively investigated. FT-IR spectra show that carboxyl groups exist on the surface of the OCNF, which greatly influence the morphology and crystallinity of the electrocatalysts. Transmission electron microscopy and X-ray diffraction consistently show that PtRu/RCNF has a smaller particle size and more uniform distribution than PtRu/OCNF. However, both catalysts have very similar methanol oxidation peak current densities that are significantly lower than commercial catalyst based on current-voltage (CV) results. These two catalysts also give very similar single cell performance except for some difference in the resistance polarization region. The OCNF supported catalysts give better performance than commercial catalysts when current density is higher than 50 mA cm(-2) in spite of low methanol oxidation peak current density. These results can be ascribed to the specific surface and structural properties of carbon nanofibers. (C) 2005 Elsevier Ltd. All rights reserved.