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A vapor‐feed direct methanol fuel cell based on a Nation 117® solid polymer electrolyte was investigated. Pt‐Ru/C and Pt/C catalysts were employed for methanol oxidation and oxygen reduction, respectively. The structure, surface, and morphology of the catalysts were investigated by x‐ray powder diffraction, x‐ray photoelectron spectroscopy, and transmission electron microscopy. Crystalline face‐centered cubic phases were found in the Pt and Pt‐Ru catalysts. The alloy composition in the Pt‐Ru/C catalyst was different from the nominal composition, probably due to the formation of surface RuOx species, as indicated by x‐ray photoelectron spectroscopy. Transmission electron microscopy observation showed an increase of the average particle size and particle agglomeration in the Pt‐Ru/C catalyst compared to the Pt/C catalyst. The membrane/electrode assembly was prepared by using a “paste process” method. Scanning electron microscopy and energy dispersive x‐ray analyses showed good adhesion of catalyst layers to the membrane and a homogeneous distribution of the ionomer inside the catalyst. AC‐impedance and galvanostatic steady‐state polarization techniques were used to investigate the electrochemical performance of the direct methanol fuel cell.

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