Characterization and PEMFC application of a mesoporous sulfonated silica prepared from two precursors, tetraethoxysilane and phenyltriethoxysilane

In this study, the mesoporous phenyl-silica (PS) is synthesized with tetraethoxysilane (TEOS) and phenyltriethoxysilane (PTES) as the Si-precursors. Then PS is sulfonated by the simple sulfonation with concentrated sulfuric acid to prepare the mesoporous sulfonated-phenyl-silica (SS). The Nafion®-based nanocomposite membranes, N/PS and N/SS, are successfully prepared with PS and SS silicas, respectively, and used as PEM for preparation of the PEMFC single cells. It is found that compared with the Nafion® membrane, NRE-212, and N/PSs, the best N/SS, SS1, which contains 3 wt.% of SS1 with about 5.18 wt.% sulfonic acid groups, exhibits more than 2-folds higher water uptake and slightly higher ion-exchange capacity (IEC). The highest proton conductivity of the as-prepared nanocomposite membranes at room temperature is in the same order as that of NRE-212. The power density of the PEMFC single cell fabricated with the best N/SS is 460 mW cm−2 at 110 °C under the humidified condition, which is approximately 13% and 53% higher than that with the N/PS and NRE-212. Besides, the peak power density obtained at 65 °C under dry condition is 414 mW cm−2, which is approximately 4 times higher than that of the N/PS.

► A sulfonated SiO2 (SS) was prepared by sol–gel method and sulfonation with H2SO4. ► The Nafion composite membrane (N/SS) exhibits more than 2-folds higher water uptake. ► Under dry condition, the power density of N/SS at 65 °C was improved for 4 times.