1 Institute of Chemical Engineering, Biotechnology and Environmental Technology, Faculty of Engineering, SDU2 Institute of Chemical Engineering, Biotechnology and Environmental Technology, Faculty of Engineering, SDU
The implement of polymer impregnation in electrode structure (catalyst layer) decreasing the noble metal catalyst loading by a factor of ten , , is one of the essential mile stones in the evolution of Proton Exchange Membrane Fuel Cells’ development among the application of catalyst support and electrode deposition etc. In fuel cell reactions, both electrons and protons are involved. Impregnation of Nafion ionomer in catalyst layer effectively increases the proton-electron contact, enlarge the reaction zone, extend the reaction from the surface to the entire electrode. Therefore, the entire catalyst layer conducts both electrons and protons so that catalyst utilization in the layer is improved dramatically. The catalyst layer will in turn generate and sustain a higher current density. One of the generally adapted methods to impregnate Nafion into the catalyst layer is to mix the catalysts directly with the Nafion, especially supported catalysts, and then use the resulting mixture to fabricate the catalyst layer. The mixing ratio, mixing condition and most important interactions, between Nafion ionomer and the catalysts/support (of different surface area, wetting property, and porosity) play a significant role in the performance of the final electrode product. In this work, ex situ study of Nafion ionomer isothermal adsorption on catalysts / support materials is carried out. Experimental technique and method are improved based on earlier experience. Observation of Nafion ionomer in aqueous solution is assisted by 19 fluorine nuclear magnetic resonance spectroscopy (19F-NMR).