Mesoporous ceria-silica/poly(arylene ether sulfone) composite membranes for durability of fuel cell electrolyte membrane

Sulfonated poly(arylene ether sulfone) (sPES)/mesoporous ceria-silica electrolyte composite membranes were prepared using a solvent casting method. The composite membranes with two components were prepared well on glass dish using dimethyl sulfoxide (DMSO) as well as N,N-dimethyl acetamide (DMAc) solvents, at various concentrations from 2.5 up to 30 wt% of the mesoporous ceria-silica powder. The degree of sulfonation was 50% for sPES and the mesoporous ceria-silica material had a 2D hexagonal (p6mm) mesostructure with the Ce/Si ratio of 0.5 and the sulfur atoms of 3.1 mmol/g in sulfonic acid groups. The oxidation stability against hydroxyl radicals ([rad]OH) was investigated both with Fenton's test and the hydrogen peroxide exposure. Hydrogen peroxide vapor exposure experiments was developed to screen the oxidation stability in a short time under high temperature and low relative humidity conditions, which is more similar to actual fuel cell system. The composite membranes exhibited higher oxidation stability than a pristine sPES membrane. However, the proton conductivity decreased with the incorporation of mesoprous ceria-silica, which should be resolved through further study using combination of the polymer matrix with different structure and the modification of mesoporous ceria-silica.