Development of sulfonated poly(ether ether ketone)/zirconium titanium phosphate composite membranes for direct methanol fuel cell

The present work addresses the development of economic membrane material with superior proton conductivity and less methanol crossover. Sulfonated poly(ether ether ketone) (SPEEK) composite membranes with various loading of zirconium titanium phosphate (ZTP) have been prepared by solution casting method. The structural and thermal properties of the ZTP powder are evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), BET surface area measurement, Fourier transform infrared spectroscopy (FTIR), and Thermo gravimetric analysis (TGA). The produced composite membranes are also characterized by evaluating the ion exchange capacity (IEC), water uptake, methanol uptake, thermal stability, proton conductivity, and methanol crossover as a function of ZTP loading. The proton conductivity of composite membrane is fourfold higher than that of the pure SPEEK membrane and also increases with an increase in the ZTP loading. The methanol permeability of the composite membrane containing 15% ZTP decreases by 264% (and 21%) when compared with pure SPEEK (and commercial Nafion 117 membrane). Over all, the selectivity of the SPEEK/ZTP composite membrane is found to be 15- and 3-fold higher than the pure SPEEK membrane and Nafion 117 membrane, respectively. Hence, the synthesized SPEEK composite membrane could be utilized as low cost alternative for the high cost commercial membranes. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012