Synthesis and Characterization of Surface Coated Silicotungstic Acid/Nafion Composite Membrane for Direct Methanol Fuel Cells

A composite proton exchange membrane (PEM) from surface coated silicotungstic acid (SiWA) and Nafion^TM for direct methanol fuel cells have been synthesized and characterized. Surface polymerization of sodium 4-vinyl benzene sulfonate (S4VBS) on SiWA has been accomplished by using atom transfer radical polymerization (ATRP). The ion exchange of sodium with hydrogen has been done by immersing the composite membrane in 2M sulfuric acid solution and sonicated for 10 minutes. The incorporation of surface coated SiWA in composite membrane resulted in homogenous membranes. It is expected to suppress the methanol crossover within PEM. The DMFCs have been fed with 5, 10, and 15 vol.% methanol solution and tested at room temperature. From polarization curve, DMFCs is fed with methanol solution 15 vol.% generated highest power output.