The Role of Reaction Parameter on Leaching of SiO2 Doped Nafion Membrane for Use in High Temperature PEM Fuel Cells

The Nafion 117 membrane was doped with SiO2 particles by sol-gel reaction.The reaction conditions to minimize leaching were investigated by usingfull factorial design of experiment. The results from the full factorial analysisindicated that the lowest amount of leaching takes place at 60oC without additionof acid and swelling of membranes prior to the reaction. The membranes, preparedat optimum reaction conditions, were characterized using differential scanningcalorimetry (DSC), and for water uptake, ion exchange capacity, and cell performance.The water uptake of Nafion/SiO2 membrane with 7% of doping level increasedup to 44% that is 26% higher than that of the pure Nafion membrane. The same trendwas obtained for proton exchange capacity. DSC Measurements for modified samplesshowed an increase in Tg as compared to unmodified sample. Fuel cell test wascarried out at 70oC and 110oC. At 110oC the modified membrane with 7 wt% of SiO2showed improved fuel cell performance compared to the pure Nafion. For instance,at 200 mA/cm2 the voltage gained by composite membrane was twice higher thanthat of the pure Nafion.