Proton exchange nanocomposite membranes based on 3-glycidoxypropyltrimethoxysilane, silicotungstic acid and α-zirconium phosphate hydrate

Novel fast proton-conducting GPTS–STA–SiO2 and GPTS–STA–ZrP composites were successfully fabricated. The polymer matrix obtained through hydrolysis and condensation reaction of 3-glycidoxypropyltrimethoxysilane (GPTS) showed apparent proton conduction at high relative humidity with conductivity from 1.0×10−7 to 3.6×10−6 S/cm, although no proton donor was incorporated. The proton conductivities of the fabricated composites were high, and increased up to 1.9×10−2 S/cm by addition of silicotungstic acid (STA). By incorporating α-zirconium phosphate (ZrP) into the GPTS–STA polymer matrix, the composite showed increased conductivity at low temperature (∼80°C), indicating weak dependence on humidity by molecular water in ZrP. The high proton conductivity of the composites is due to the proton conducting path through the GPTS-derived ‘pseudo-polyethylene oxide (pseudo-PEO)’ networks, which also contains a trapped solid acid (silicotungstic acid) as a proton donor.