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

直接甲醇燃料电池（DMFC）因其能量转换效率高、污染物排放少、甲醇能量密度高、燃料可用性高等特点而受到广泛关注。但也存在一些问题，制约了DMFC的应用。这些需要解决的问题包括甲醇活性低和耐CO_2。为了提高甲醇氧化的催化活性，人们对铂合金催化剂进行了大量的研究，以减少催化剂的中毒。采用醇还原法和反相微乳液化学还原法制备了碳载体上高度分散的Pt和Pt- ru合金颗粒。采用紫外可见光谱、x射线衍射、电子显微镜、x射线光电子能谱、循环伏安法和CO条带法对催化剂进行了表征。前一种方法具有简单易行、不经任何改性直接还原氯化物盐的优点。后一种情况下，纳米颗粒的平均尺寸约为2 ~ 4 nm，分布较窄。此外，它们在碳载体上均匀分布。结果表明，纳米颗粒的粒径大小与微乳液中水的体积有关。此外，CO溶出伏安法和CO/H_2和甲醇的电化学氧化实验表明，合成的双金属颗粒具有较高的比表面积和良好的CO和甲醇氧化催化活性。研究了Pt_3Ru_2Sn和Pt-Ru-Fe催化剂的制备和表征。Pt-Ru- sn催化剂的催化活性明显高于Pt-Ru催化剂。在三元合金催化剂中加入Sn修饰了Pt的电结构，但没有使Pt-Pt键距大幅增加，这可能是通过提高CO耐受性来提高甲醇氧化的催化活性。其次，研究了Pt_3Ru_2Fe催化剂的催化活性。Pt_3Ru_2Fe催化剂的甲醇氧化活性比Pt-Ru催化剂提高了2.5倍。少

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