| Direct methanol fuel cell (DMFC) has a promising prospect by widely applied in portable power supplies because of the advantages such as rich fuel, high power density, and friendly environment. Electrocatalyst is crucial for the performance of DMFC. When the active component of a catalyst is certain, the properties and morphology of carbon support will directly affect the catalyst activity and stability. Vulcan XC-72(XC-72), a kind of carbon black, is mostly used as the electrocatalyst support. However, its-supported catalysts may lead to a close pack during the hot-press process of electrode fabrication, thus block reactants to get access to inner active sites, resulting in a decreased utilization of catalyst.In this thesis, XC-72, carbonnanotubes (CNTs), and a home-made coiled carbon nanotubes (CCNTs) which synthesized by solid-state catalytic method have been applied as electrocatalyst support in order to combine the advantages of each carbon nanomateiral during electrode reactions, and then overcome the deficiency of XC-72in mass transport and electron/proton transfer. Firstly, Pt and PtRu nanoparticles supported on each carbon material have been synthesized by a modified ethylene glycol method. Subsequently, each two and three kinds of above catalysts were mixed with different mass ratios, and their electrocatalytic performances were investigated. Furthermore, three kinds of carbon materials with different mass ratioswere mixed as support before synthesized a series of cathode and anode catalysts. The physical property, morphology, structure, and electrochemical performance of carbon mateirals and electrocatalysts have been investigated by means of BET&BJH, transmission electron microscopy (TEM), X-ray diffraction (XRD), and cyclic voltammetry (CV), etc.Experimental results show that the obtained CCNTs, with well-defined graphitic coils and moderate mesopore morphology, can be an excellent catalyst support. Among the mixed cathode catalysts composed by two kinds of catalysts, the optimum combination was Pt/C and Pt/CCNTs catalysts with mass ratio of95:5, and the electrochemical specific surface area (ECSA) was106m2/gpt, with respect to69m2/gpt of commercial Pt/C catalyst (JM) supported on XC-72. Among the mixed catalysts with Pt/C, Pt/CNTs, and Pt/CCNTs, the optimum mass ratio was80:10:10corresponding to ECSA of111m2/gpt. According to the linear sweep voltammetry results, this mixed catalyst also exhibits the highest current density of4.7mA/cm2as compared to2.1mA/cm2of Pt/C at potential of0.5V vs. Ag/AgCl, which demonstrate its good oxygen reduction reaction activity.For the mixed anode catalysts, the peak current of PtRu/XC-PtRu/CNTs with opitmum mass ratio of80:20is5.3mA, which is higher than that of PtRu/XC, PtRu/CNTs, or PtRu/CCNTs. For the mixed PtRu/CNTs and PtRu/CCNTs, it can be observed the methanol oxidation reaction (MOR) peak current increases from1.6mA to3.5mA with increasing PtRu/CNTs content, and for the mixed PtRu/XC and PtRu/CCNTs catalysts, the peak current of MOR increased from3.7mAto5.2mA with adjusting the mass ratio from1:1to95:5. For the mixed PtRu/XC72, PtRu/CNTs, and PtRu/CCNTs catalysts with optimum mass ratio of80:10:10, the peak current is5.6mA. And it possessed highest â… f/â… b of6.3, which suggest that this mixed catalysthas better MOR activity and CO tolerance ability than individual catalyst or two mixed catalysts.For the mixed carbon material-supported catalysts, the optimum proportion of XC-72, CNTs, and CCNTs is8:1:1, and it only has a similar ECSA to that of commercial Pt/C. And for the anode catalyst with same ratio, it shows an enhanced peak current of4.8mA, which is higher than that of PtRu/C (JM), PtRu/CNTs, or PtRu/CCNTs catalyst.Combined application of XC-72, CNTs, and CCNTs carbon materials in catalyst layers can improve the catalytic activity of electrocatalysts, and mixed catalysts show better performance that mixed carbon material-supported catalysts. This result can be applied in practical electrode fabrication to enhance the performance of DMFC.
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