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 using full factorial design of experiment. the results from the full factorial analysis indicated that the lowest amount of leaching takes place at 60oc without addition of acid and swelling of membranes prior to the reaction. the membranes, prepared at optimum reaction conditions, were characterized using differential scanning calorimetry (dsc), and for water uptake, ion exchange capacity, and cell performance. the water uptake of nafion/sio2 membrane with 7% of doping level increased up to 44% that is 26% higher than that of the pure nafion membrane. the same trend was obtained for proton exchange capacity. dsc measurements for modified samples showed an increase in tg as compared to unmodified sample. fuel cell test was carried out at 70 oc and 110 oc. at 110 oc the modified membrane with 7 wt% of sio2 showed improved fuel cell performance compared to the pure nafion. for instance, at 200 ma/cm2 the voltage gained by composite membrane was twice higher than that of the pure nafion.