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Abstract
Chemical durability of membranes plays an important role for the lifetime and commercial viability of the proton exchange membrane (PEM) fuel cells. In this study, a novel nanocomposite membrane based on Nafion and sulfonated SnO2/SiO2 (SnO2/SiO2-SO3H) was prepared by the solution-casting method. The design of nanocomposite membrane was based on the mitigation of membrane chemical degradation while keeping the proton conductivity as high as possible. The water uptake, ion exchange capacity, proton conductivity and thermal stability of membranes were studied. The results revealed that the proton conductivity of the Nafion/SnO2/SiO2-SO3H membranes is slightly lower than those of the pure Nafion membrane. However, the proton conductivity of the Nafion/SnO2/SiO2-SO3H membrane is higher than that of the un-sulfonated Nafion/SnO2 membrane. Fenton's test was used as an ex situ accelerated test to evaluate the chemical durability of membranes. The results indicate that the fluoride release and weight loss in Nafion/SnO2/SiO2-SO3H nanocomposite membranes are less than those in the pure Nafion membrane, which indicates the more chemical durability of Nafion/SnO2/SiO2-SO3H nanocomposite membrane. These findings were further confirmed by ATR-FTIR spectra and SEM surface images of membranes.