Preparation And Characterization Of Modified Nafion Membranes For Fuel Cells

The proton exchange membrane (PEM), a key component of proton exchange membrane fuel cells (PEMFC), has dual functions of proton conduction and separation of the anode from the cathode. So far, perfluorinated sulfonic acid ionomer membranes have been used in practical fuel cells, their high cost and humidification systems are the important factors for retarding the commercialization of PEMFC. Product of self-humidification PEM can simplifying the PEMFC system. In order to improve the self-humidification capability of perfluorinated sulfonic acid ionomer membranes,this thesis did some interrelated reseerch.Firstly, nanometer titanium dioxide (TiO₂) has been mixed with Nafion solution, which was re-dissolved by DMF.TiO₂/Nafion composite membranes were produced via this perfluorosulfonic acid resin solution. TiO₂/Nafion composite membranes were characterized.The TiO₂ has excellent capability of adsorbing water,can reduce fuel gas humidification systems hopefully, so has some foreground for application.Then,Pt/CNTs-TiO₂/Nafion composite membranes were prepared base on the TiO₂/Nafion composite membranes. These membranes make up of three layers, both the outboard layers are Pt/CNTs catalyst, and the middle is TiO₂/Nafion composite membrane.The Pt/CNTs outboard can catalyze H₂ and O₂ permeating through the membrane from the anode and cathode to produce water,which improves problem of water loss on the anode. On the other hand,nanometer titanium dioxide in the middle layer can adsorb water to remain membrane wet, is propitious to simplifying operation systems of Fuel Cell.