| Recently direct methanlol fuel cell (DMFC) has been widespread attentions because of the abundant source, the inexpensive price, easy storage and transportation of the liquid methanol as well as the small volume and weight, the simple structure, easy operation and maintenance, the low cost of DMFC. Therefore, DMFC is viewed as one of the most promising mobile power sources. Although Pt-Ru/C catalysts have been used widely as anodic catalysts in DMFC, the poor electro-catalytic activities are the one key issue hindering DMFC commercial application.Rare earth element has been used as co-catalyst in the field of methanol electro-catalytic material because of its unique 4f electron structure. Pt-Ru-Ln (Ln = La,Ce,Sm,Eu,Dy,Ho,Lu,Y ) alloy particle can avoid effectively electrochemical erosion of rare earth element. Rare earth element can translate d electron structure of Pt because of its 4f electron structure and vacant d electron structure. It is important to improve electro-catalytic activities of Pt-Ru/C catalysts.In this work, Pt-Ru/C catalysts doping with rare earth element were prepared by pulse electro-deposition method. The micro-structure and composition of Pt-Ru-Ln/C catalysts were characterized by XRD, EDS and XPS. The activities of the Pt-Ru-Ln/C catalysts were characterized by cyclic voltammetry (CV) and electrochemical impedance spectrum (EIS).The results indicated that the catalyst material are consist of Pt-Ru-Ln alloy particles and varying amounts of Ln oxide. The average particle size and special active area of catalysts are about 2～4 nm and 50～90 m2·g-1, respectively. The proportion of metal element in alloy particle was coincided with precursor.In the same pulse electro-deposition process and content of rare earth element, the order of the activities of Pt-Ru-Ln alloys is Pt-Ru-Eu/C≈Pt-Ru-Ho/C> Pt-Ru-Dy/C>Pt-Ru-Sm/C≈Pt-Ru/C> Pt-Ru-La/C> Pt-Ru-Ce/C> Pt-Ru-Y/C≈Pt-Ru-Lu/C. Doping with Eu and Ho can enhance markedly the activities of Pt-Ru alloy for methanol electro-catalytic oxidation; Doping with Dy and Sm can improve relatively, but doping with La, Ce,Y and Lu element reduced activities of Pt-Ru alloy.Tafel constant a of Pt-Ru-Eu0.2/C and Pt-Ru-Ho0.2/C catalysts are lower than that of Pt-Ru/C catalysts. The current density on Pt-Ru-Eu0.2/C and Pt-Ru-Ho0.2/C catalysts are 67.5 mA·cm-2 and 66.8 mA·cm-2 in 0.5mol L-1 H2SO4 + 0.5 mol L-1 CH3OH solution in our work, respectively.Reactive initiative potential reduced 0.05 V in comparison with Pt-Ru/C catalyst.With the enhancement of methanol concentration and temperature, methanol electro-catalytic oxidation rate of Pt-Ru-Eu0.2/C and Pt-Ru-Ho0.2/C catalysts are of great improvement. The stability of Pt-Ru-Eu0.2/C catalyst was evalulated using cyclic voltammetry method. The results indicated that the stability of Pt-Ru/C catalyst doping with rare earth element Eu is correspond to Pt-Ru/C catalyst.The particle size of Pt-Ru-Eu0.2/C catalyst increased from 4.6 nm to 5.1 nm with the testing time. The electro-catalytic activity of Pt-Ru-Eu0.2/C is still higher than that of Pt-Ru/C because the catalyst materials contain of Pt-Ru-Eu alloy.
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