(457g) Characterization of a Nanostructured Sulfated Zircona Based Proton Exchange Membrane for Direct Methanol and Formic Acid Fuel Cells

Sulfonated perfluorcarbon polymers such as Nafion®, which are today standard for proton exchange membrane materials, are unable to withstand high temperatures or perform adequately at low hydration levels. To address these problems, a number of alternative proton exchange membrane materials have been investigated. Ceramics can materials are generally hydrophilic and can withstand extremely high temperatures. Evidence from the literature suggests that proton conductivity increases in most PEM materials with the number and strength of surface acidic cites. This work demonstrates nanostructured porous sulfated zirconia, a superacidic ceramic, as an effective alternative PEM material for direct methanol and direct formic acid fuel cells. Electrochemical impedance spectroscopy was utilized to examine the proton conductivity as well as to illucidate the proton conduction mechanism in the material. Water retention and surface acidity was studied using thermogravimetric analysis. Crossover measurements with both methanol and formic acid were also performed. Lastly, the membrane was incorporated into a simple membrane electrode assembly to demonstrate its viability in a fuel cell. The effects of different nanofabrication procedures, calcination temperature, zirconia precursor, and sulfonation methodology were studied.