Studies on the Improvement of catalytic performance for direct methanol fuel cell

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Direct methanol fuel cells(DMFC) have been received much attention because of their characteristics such as high energy conversion efficiency, low pollutant emission, high energy density of methanol, and fuel availability. However, there are some problems, inhibiting the application of DMFC. These problems to be solved involve the low activity of methanol and CO_2 tolerance. To enhance the catalytic activity of methanol oxidation, there are intensive researches on Pt alloy catalysts that minimize the catalyst poisoning.In the present work, the highly dispersed Pt and Pt-Ru alloy particles on carbon support were prepared by alcohol-reduction method using polyvinylpyrolidone as a stabilizer, and by chemical reduction method using reverse microemulsion. The prepared catalysts were characterized by UV-visible spectroscopy, x-ray diffraction, electron microscopy, x-ray photoelectron spectroscopy, cyclic voltammetry, and CO striping method. The former method has advantages over simplicity an … More d straight reduction of chloride salt without any modification. In the latter case, the average size of nanoparticle was ca. 2-4 nm with narrow distribution. Moreover, they are homogeneously dispersed on carbon support. It is cleared that the particle size of nanoparticle was dependent on the water volume in microemulsion. In addition, CO stripping voltammetry and the electrochemical oxidations of CO/H_2 and methanol showed that the synthesized bimetallic particles had a high surface area and a good catalytic activity for the oxidations of CO and methanol.The preparation and characterization of Pt_3Ru_2Sn and Pt-Ru-Fe catalysts were investigated. The catalytic activity of Pt-Ru-Sn catalyst was significantly higher than that of Pt-Ru. Sn in ternary alloy catalyst modified the Pt electric structure without the large increase of Pt-Pt bond distance, which may enhance the catalytic activity for methanol oxidation by improving CO tolerance. Next, the catalytic activity of Pt_3Ru_2Fe catalyst was studied. The activity of methanol oxidation of Pt_3Ru_2Fe catalyst was 2.5 times higher than that of Pt-Ru catalyst by the enhanced CO tolerance. Less