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

Abstract

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 (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.