Studies On Pt/C And Alloy Catalyst For Proton Exchange Membrane Fuel Cells

Most of the catalysts used in the proton-exchange membrane fuel cell (PEMFC) are the Pt/C catalysts at present. Because the resource of the platinum is very lacking, it is very important to find a new way to make the low loading platinum catalyst with high performance.In this thesis a few methods for preparing the Pt/C catalyst are compared. The low loading Pt/C catalyst prepared by impregnation and ion exchange method was compared and investigated. The catalysts were characterized by TEM and CV. The results show that the diameter of Pt particle prepared by ion exchange method is circa 1.5-2.5 nm, it is less than the diameter of Pt particle prepared by impregnation method (3-4.5 nm). It is an effective way to increase the surface area of Pt/C catalyst to prepare catalyst by ion exchange method. The Pt/C catalysts prepared by these two methods were tested in the PEMFC. It was found that the catalyst prepared by ion exchange method had higher performance than that prepared by conventional impregnation method.The exchange current density of the oxygen electrode is so low that the over-potential mostly happens on the cathode in the fuel cell. In order to improve the performance of the fuel cell, we must enhance the activity of the catalyst on the cathode to reduce the over-potential.In this thesis, the alloys of Pt and Ni were made and used as the cathode catalyst. By the contrast of the two kinds of catalysts' electrode kinetic parameters, we find that the exchange current density of cathode doubled.