High proton conductive advanced hybrid membrane based on sulfonated Si-SBA-15

Composite membranes based on Sulfonated poly(ether ether ketone) (SPEEK) and sulfonated organically modified Si-SBA-15 (S-SBA-15) were investigated with the purpose of increasing the proton conductivity. The novelty of the composite membranes was attributed to two special structures and different ion exchange capacities (IEC) of S-SBA-15 fillers, which were embedded in membranes. The typical hexagonal channels array of S-SBA-15 was confirmed by XRD and TEM. The regular vermiculate and amorphous structures of the inorganic fillers were proved by SEM. Composite membranes were prepared through common solvent casting method. SEM images indicated that the inorganic filler with regular structure dispersed homogeneously in the composite membranes, but the amorphous filler caused an agglomeration phenomenon at the same loading content. The composite membranes exhibited good thermal stability, enhanced water uptake and proton conductivity. The proton conductivity of the composite membranes with low IEC filler was higher than the composite membranes with high IEC filler at the same loading content. The highest proton conductivity value of 0.156 S cm−1 was obtained for the composite membrane containing 5 wt.% S-SBA-15 with the IEC of 1.41 mequiv g−1 at 80 °C. This composite membrane also showed other promising properties such as good thermal and mechanical stability which exceeded the other composite membranes with different loading contents.