Direct Methanol Fuel Cell: Studies On The Preparation Of Highly Dispersed Pt Based Electrocatalysts With High Loading

Highly dispersed carbon supported Pt based metal catalysts with high metal loading (40~60wt.%) are known to be efficient electrocatalytic material in direct methanol fuel cells (DMFCs). hi this dissertation, a novel synthesis of this kind of electrocatalysts was explored and the effects of several preparation variables on the particle size and morphology of electrocatalysts were studied. Some in-situ and ex-situ techniques were employed to provide clues for fundamental understanding of preparation process. The particle size, morphology, electrocatalytic activity and stability of in-house electrocatalysts were measured and compared to the same type of commercial electrocatalysts. hi addition, some preliminary exploration on Pt-MoiC/C, Pt-MoP/C and PtRu-MoP/C as new anode electrocatalysts were carried out.Optimizing experiments of preparation variables show that pH value, reduction temperature, addition sequence and volume, impregnation duration and lighting all have significant influence on the particle size and morphology of as-synthesized electrocatalysts during polyol process. The particle size of the electrocatalysts can be finely tuned to favorable nanometer size by changing some preparation variables by this method. Characterization of preparation process inferred that most of the metal particles formed in solution firstly and then deposited to carbon support after addition of sedimentation agent.The results of XRD, TEM and chemisorption consistently demonstrate that nanopaticles in in-house electrocatalyts are smaller and much uniform than that of the same type of commercial electrocatalysts. The single DMFC employing in-houseelectrocatalysts exhibit higher performance and better stability compared to the commercial electrocatalysts.Some preliminary exploration on Pt-MoiC/C, Pt-MoP/C and PtRu-MoP/C as new anode electrocatalysts were carried out to study their preparation, activities and stabilities in DMFC. The results display that the Pt-Mo2C/C with 3wt.% Pt loading has good stability during the cyclic voltammetry. However, the performance of single DMFC employing these electrocatalysts is lower than that of PtRu/C electrocatalyst.