Research On Electrode Fabrication For Direct Methanol Fuel Cells By Pulse Electrodeposition

Recently developed direct methanol fuel cells (DMFCs) has been received widespread attention due to the abundant sources, the low price, the safety of the storage and transportation of the fuel, inherent simplicity of design and operation, high energy efficiency, small weight and volume, and low pollution. However, some problems, such as low electrocatalytic activity of the anode catalyst restrict its practical use. In this thesis, in order to reducing the amount of the Pt/Ru catalyst and improving the electrocatalytic activity of the Pt/Ru catalysts, the pulse elelctrodeposition methode was used to prepare the electrode of Pt/Ru with high dispersibility and utramicro particles. Using the XRD and EDS techniques, the size and the effective surface area of the Pt and PtRu particles prepared with pulse electrodepositionmethods were studied. The electrocatalytic activities and stability for methanol oxidation were evaluated with the electrochemical techniques. And the dynamic equation for methanol oxidation was simulated. The main results obtained are as follows:Investigating experiments of electrodeposition variables show that duty cycle, frequency have significant influence on the particle size and morphology of the electrode. This proved that the pulse electrodeposition method have the advantage of simplicity and controlled particles size.Optimizing experiments of electrode composition show that the electrocatalytic active and stability for the methanol oxidation for the electrode loading PtRu fabricated with the pulse electrodeposition are much better than that of Pt/C or PtRu/C catalysts prepared with traditional methods. For example, for the electrode loading Pt or PtRu catalysts fabricated with the pulse electrodeposition method, the diameter of the Pt or PtRu particles is 3.2nm, the electrochemical active surface area is 86m2/g. In the cyclic voltammetry obtained in the 0.5mol/L H2SO4 + 0.5mol/LCH3OH solution, when the temperature is 25 °C, scan rate is 5Mv/s, the peak current density for oxidation methanol is about 80mA/cm2, the peak potential is about 0.61V, the initial oxidation potential is about 0.15V.Using RDE technique, the dynamic parameter for oxidation methanol was simulated.