Preparation And Characterization Of Pt/C Catalysts Modified With Nafion For PEMFC

Pt-based catalysts are usually employed as anode and cathode catalysts in proton exchange membrane fuel cell(PEMFC). But the bond between the Pt particle and the support carbon is week, which makes Pt particle readily move and agglomerate or sinter during the long-time run of PEMFC. In this study, the novel Pt/C catalysts modified with perfluorosulfonic acid(PFSA) such as Nafion was prepared to enhance the bond between the Pt particle and the support carbon. PFSA may act as protection agent as well as cohesive material. The Pt/C catalysts with nation-protected Pt (Pt-nafion/C) and with nafion-decorated support carbon(Pt/nafion-C) were prepared by the colloid method and the liquid phase reduction respectively. The structure, performance and durability of the prepared catalysts were characterized by TEM, XRD, XPS, CV and electrochemical acceleration respectively. The experimental results and conclusions are summarized as following:(1)The Pt particle in Pt-nafion/C catalysts is uniform and has narrow size distributions. XPS shows the proportion of Pt(metal) in 40%Pt-nafion/C is 79.3%, which is higher than that in commercialized 40%Pt/C catalyst (70.5%). However, the electrochemical surface area(ECSA) of the former is lower than that of the latter. The electrochemical acceleration shows the 40%Pt-Nafion/C catalyst has more advantaged durability than that of 40%Pt/C: The ECSA of the former is reduced by 62% over 12300 cycles, while the latter is reduced by 65% only over 4500 cycles.(2) The Pt particle in 20% Pt/nafion-C catalysts possesses uniform and narrow size distributions with average diameter of 2.40 nm. XPS shows the proportion of Pt (metal) in 20%Pt/nafion-C is 71.1%, which is nearly as much as that in commercialized 20%Pt/C catalyst(70.5%). ECSA of the former is higher than that of the latter. The electrochemical acceleration shows the 20%Pt/Nafion-C catalyst has better durability than that of 20%Pt/C: The ECSA of the former is reduced by 63% over 5800cycles, while the ECSA of the latter is reduced by 67% only over 3500 cycles.This study prove that it is feasible to enhance the durability of Pt/C catalysts by introducing PFSA acting as protection agent as well as cohesive material between Pt particle and supporter. The nolve catalysts are promising application in PEMFC.