Preparation And Electrocatalysis Research Of Pt Based Ordered Intermetallic Compounds

Direct alcohol fuel cells, the fuels of which are small organic molecules such as methanol, ethanol, isopropanol and formic acid are the new types of low temperature fuel cells. However, the poisoning of the anode electrocatalysts has affected performance and service life of fuel cells. The preparation of PtPb,PtSn,PtBi ordered intermetallic compounds is studied in this paper, and the electrochemical performance of these compounds is researched in the solutions of ethanol and formic acid. The compositions and particle sizes of the prepared composite catalysts were characterized by XRD.The results showed that the quantity of polyvinylpyrrolidone (PVP) as a polymer stabilizer, the temperature of reaction and the ratio of atom had the varying degree influence to the electrocatalysts preparation during the process of preparing PtPb, PtSn, PtBi ordered intermetallic compounds using the alcohol-reduction method.In the electro-oxidation reaction of ethanol, when the quantity of PVP is 170mg, and the temperature of reaction is 170℃, the PtPb/C catalyst with the Pt/Pb atomic ratios of 1:1 in the solution had the best performance. During the process of preparing the PtSn/C ordered intermetallic compound, the degrees of orderliness of the PtSn alloy increased with the increase of the quantity of PVP in some degree. It had affected the electrocatalytic performance of the PtSn/C catalyst, and the best quantity of PVP was 170mg. The temperature of reaction also had the influence to the catalytic activity for electro-oxidation of the PtSn/C catalyst. And the best reacting temperature was 240℃. The electrocatalytic performance of the PtSn/C catalyst was increased with the quantity of Pt in the solution. The best the best atomic ratios of Pt/Sn was 3:1. Compared the performance test of the PtSn/C catalyst with that of the commercial Pt/C in the solutions of ethanol and formic acid, it found that the properties of the PtSn/C catalyst were improved in some degree. At the room temperature, when the quantity of PVP is 100mg, and the Pt/Bi atomic ratios were 1:3, the catalytic activity for the ethanol electro-oxidation of the PtSn/C catalyst has the best performance.In the solutions of ethanol and formic acid, the electrochemical impedance spectroscopy of those catalysts was studied. New equivalent circuit was presented to fit the experimental electrochemical impedance spectroscopy. The electrode reaction mechanism of PtPb/C, PtSn/C and PtBi/C catalysts was investigated in the solutions of ethanol and formic acid. For the first time, the electrode reaction mechanism of PtPb/C, PtSn/C and PtBi/C catalysts was investigated by the rotating disk electrode in the solutions of ethanol.