| Direct methanol fuel cell (DMFC) use cheap methanol as the fuel. It does not need the fuel reforming equipment. Its operating temperature is low. The fuel source is abundant and is easy to store and to transport. Therefore, it is an ideal power for mobile electronic equipment and electric automobiles. Recently, many countries invest lot of the enormous manpower and material resource to carry out its fundamental and applied research. However, due to its high toxicity, it is necessary to find a new liquid fuel to displace the methanol in order to realize the application of DMFC used for the power of the mobile phone, mobile computer and electric automobiles. Ethanol is easy to obtain from biomass on the large scale and it is not toxic. Thus, it is possible to be applied for the fuel in the fuel cell.In this thesis, the effects of the preparation methods of Pt/C and Pt-Ru/C catalysts and the average diameter of the catalyst particles on the electrocatalytic performance of the catalysts for the ethanol oxidation are investigated using the electrochemical methods and XRD , TEM, EDS techniques. The main results obtained are as follows:1. The electrocatalytic activities of the Pt/C catalyst prepared with the solid phase reaction method for the ethanol oxidation is reported for the first time. It was found that the electrocatalytic activity of the Pt/C catalyst with 20% Pt prepared with the solid phase reaction method is much better than that of the Pt/C catalyst prepared with the traditional liquid phase reaction method. For example, in the cyclic voltammogram of the Pt/C catalyst electrode prepared with the solid phase reaction method in the 0.5mol/L CH3CH2OH + 0.5mol/L H2SO4 solution, the currents of the two anodic peaks during the potential scan in the positive direction are about 7.5 and 10.5mA/cm2 , respectively. The current of the anodic peak during the potentail scan in the negative direction is about 10mA/cm2. However, under the same conditions, for the Pt/C catalyst electrode prepared with the traditional liquid phase reaction method, the currents of the three anodic peaks are 2.5, 3.0 and 4.0 mA/cm2, respectively. It is mainly due to that the average diameter of the Pt particles in the Pt/C catalyst preparedAbstractwith the solid phase reaction method is small, about 3.7nm. Thus, its utilization ratio and the electrochemical active surface area of Pt are high, about 15.2% and 31.6m2/g. However, the diameter of the Pt particles in the Pt/C catalyst prepared with the traditional liquid phase reaction method is large, about 9.0nm, Its utilization ratio of Pt and the electrochemical active surface area are low, about 3.62% and 8.60m2/g.2. It is reported for the first time that Pt-Ru/C catalyst is prepared with the solid phase reaction method and its electrocatalytic activity for the ethanol oxidation is studied. It is found that the electrocatalytic activity of the Pt-Ru/C catalyst with 30% Pt-Ru and the atom ratio of Pt:Ru=1:1 prepared with the solid phase reaction method for the ethanol oxidation are much better than that of the Pt-Ru/C catalyst with 30% Pt-Ru and the atom ratio of Pt:Ru =1:1 prepared with the traditional liquid phase reaction method. For example, in the cyclic voltammogram of the Pt-Ru/C catalyst electrode prepared with the solid phase reaction method in the 0.5mol/L CH3CH2OH + 0.5mol/L H2SO4 solution, the peak current is about 125 mA/cm2 and the peak potential is located at about 0.54V. However, for the Pt-Ru/C catalyst prepared with the traditional liquid phase reaction method, the corresponding peak current is only 60 mA/cm2 and the peak potential is located at about 0.64V. The TEM and EDS measurements indicated that it is mainly due to the high dispersibility and small diameter of the Pt-Ru particles in the Pt-Ru/C catalyst prepared with the solid phase reaction method.3. The electrocatalytic activities of the Pt/C catalysts with 20% Pt and different average diameters of the Pt particles for the ethanol oxidation were compared. It was found that when the aver... |
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