Preparation Of Pt-Based Catalysts And Their Performaces Toward Methanol/Ethanol Electrooxidation

Direct alcohol fuel cell (DAFC) is a kind of power generation devices which converts chemical energy of alcohols directly into electrical energy. It has received considerable attention due to its high energy density and relatively low operating temperature. DAFC is well suited to serve as portable power and automotive propulsion. However, the sluggish kinetics of anodic oxidation leads to a low output power, which retards the commercialization process of DAFC. Hence, it is of vital significance to develop efficient catalysts for electrooxidation of alcohols.Commercial platinum (Pt) catalyst can’t satisfy the requirements of the practical application due to the scarcity of Pt and the catalyst deactivation. Currently, platinum is still indispensable in a high performance anodic electrocatalyst. In order to improve the utilization of Pt in DAFC, Pt nanocube catalyst, Pt-Cu alloy catalyst and supported Pt/MnO2catalyst were prepared and their performances toward methanol/ethanol electrooxidation were investigated in this thesis. The main work is as follow:1. By using ascorbic acid as reductant, surfactant-free Pt nanoparticles were synthesized in N, N-dimethylformamide (DMF) solution. The influences of ascorbic acid concentration, the reaction temperature on the structure and catalytic behavior of Pt nanoparticles were investigated thoroughly. Pt nanocubes with an average size of3.5nm were obtained with the ascorbic acid concentration of50mM at150℃. The existence of{110} type sites on the Pt nanocube catalyst was demonstrated to promote the electro-oxidation of methanol and ethanol.2. With the assistance of oleic acid as growth regulator, Pt-Cu alloy catalysts were prepared in DMF solution. The influences of the ratio of metal precursors, the oleic acid concentration on the structure and catalytic behavior of Pt-Cu catalysts were explored. Pt-Cu alloy catalyst with the smallest particle size,6.30nm, was obtained when the concentration of oleic acid was30mM and the nominal ratio of Pt precursor to Cu precursor was1:1. This catalyst shows the highest activities toward methanol/alcohol electrooxidation among several as-prepared Pt-Cu catalysts.3. MnO2with various morphologies and Pt sol were prepared by the water phase synthesis and the polyol process, respectively. Pt/C and Pt/MnO2supported catalysts were prepared via a typical loading process. The catalyst with lamellar MnO2as carrier shows higher performance toward methanol/alcohol electrooxidation. As a reactive carrier, MnO2is able to enhance the performances of Pt catalyst toward methanol/alcohol electrooxidation.