Chitosan–Phosphotungstic acid Complexe and Montmorillonite Nanocomposite Membranes as High Performance Materials for Fuel Cell Applications

Fuel cells product direct current by using an electrochemical process. In direct methanol fuel cells (DMFCs) the proton exchange membrane (PEM), whichprovides protonic communications between the anode and cathode, is often considered as the key part of such configurations. The common membrane materials forDMFCs applications are the perfluorinated ionomers such as Nafion. Due to the relatively high cost of manufacturingand high methanol permeability, the utilization of Nafion membranes is limited. So a lot of researches have been devoted to find new alternative membranes instead ofNafion [1]. In this regard, Polyelectrolyte complexes (PECs) of chitosan and phosphotungstic acid (PWA) wereprepared and characterized as novel proton-conductingmembranes. PWA can be fixed within PEC membranes through strong electrostatic interactions, which avoids thedecrease of proton conductivity, caused by the dissolving of PWA in electrochemically produced water. Fouriertransform infrared spectroscopy (FTIR) demonstrates thathydrogen bonding is formed between chitosan chains and PWA. To reduce the methanol permeability several amounts ofmontmorilonite nanoclay (MMT Na, trade name: cloisite Na) were introduced to the system. The X-Ray diffraction(XRD) patterns of nanocomposite membranes proved, howclay layers are exfoliated in the samples. Proton conductivity and methanol permeability were measured.The selectivity parameter – ratio of proton conductivity to methanol permeability– was identified for the systems to choose the optimum membrane. So the goal in this research is preparing new membranes as an alternative of Nafion, based on chitosan and PWA nanocomposites