Synthesis Of Carbon Supported Pt And Pt-based Alloy Nanoparticles And Their Electrocatalytic Properties For Methanol Oxidation

Fuel cells are a kind of green power source with high efficiency, one of which is direct methanol fuel cell (DMFC). DMFC is believed to be an ideal small and mobile energy sources, it will be widely used in fields of traffic, communication, military affairs and aviation etc. There are two major problems about DMFC, one of which is that the electrocatalytic activity of methanol at anode is low, the other is that the penetration of methanol from anode to cathode is quite severe. Therefore it is a urgent need to prepare a kind of anode catalyst with high electrocatalytic activity for methanol oxidation. Transition metal Pt and its alloys are the common oxidation catalysts for organic molecules including methanol for the dehydrogenation reaction, therefore they are good anode catalysts of DMFC. The catalytic activity of the catalysts will be influenced by the size, distribution and shape of the particles, therefore it is very important to prepare catalysts with small size and homogeneous size distribution.This dissertation is mainly about the research of the Pt, PtRu, PtNi nanoparticles highly dispersed on carbon supports which are prepared by polyol process. Such analytic instruments as XRD, TEM were used to characterize the structure of the prepared Pt, PtRu, PtNi nanoparticles, whose electrocatalytic activities for methanol oxidation are analyzed by electrochemical tests.We synthesized Pt/CNTs catalysts using microwave-polyol process, by adding KOH to adjust the initial pH of reaction solution. The structures of the samples were characterized by XRD and TEM, the results indicated that the particle size of synthesized Pt nanoparticles can be controlled by the pH of reaction solution, and this controlling method was efficient and simplified. The electrochemical tests proved that the Pt/CNTs catalysts possess high electrocatalytic activity for methanol oxidation, and the results indicated that the Pt/CNTs catalysts prepared under the pH of 7.4 had ahigher electrocatalytic activity than other samples.In ethylene glycol solution, we synthesized PtRu/XC-72 catalysts with different proportion of Pt-Ru atoms by using sodium acetate as stabilizer. Such analytic instruments as XRD, TEM were used to characterize the structure of samples and the results indicated that the prepared PtRu particles had small size and homogeneous size distribution. The electrochemical tests proved that PtRu/XC-72 catalysts had high electrocatalytic activity for methanol oxidation, and they could effectively restrain CO. The results of electrochemical tests about three PtRu/XC-72 catalysts with different proportion of Pt-Ru atoms indicated that the catalyst with Pt-Ru proportion about 1:1 had better electrocatalytic activity than other samples.In ethylene glycol solution, we synthesized PtNi/XC-72 catalysts using sodium acetate as stabilizer. The results of characterization indicated that the prepared PtNi/XC-72 catalysts had small particles size and homogeneous size distribution. The electrochemical tests proved that the PtNi/XC-72 had better electrocatalytic activity for methanol oxidation and more effectively restraining effect to CO than Pt/C catalysts. And it could also be proved that the PtNi/XC-72 catalysts worked more steadily than PtRu/XC-72 catalysts when operating for long time.