The effect of excessive amount of nanosized silica on the performance of proton exchange membrane(PEM)

Abstract

Inorganic nanoparticles in nanocomposite membranes significantly affect the characteristics of those membranes, such as dimensional stability, proton transport behavior, and electrochemical single cell result. Therefore, the inorganic nanoparticles should be considerably chosen. In this study, organic-inorganic nanocomposite membranes were prepared by adding both hydrophobic ( Aerosil 812, Degussa) and hydrophilic silica (Aerosil 380, Degussa) nanoparticles into a Sulfonated poly(arylene ether sulfone) (SPAES) polymer matrix. The SiO₂ particles are evenly dispersed in a SPAES matrix by the aid of a non-ionic surfactant (Pluronics L64). A SiO₂ content plays an important role in membrane microstructures and membrane properties such as proton conductivity and water uptake. Therefore, to study nanocompoiste membranes with higher amount of silica, all nanocomposite membranes with 5 wt. % of silica nanoparticles were prepared by adding whole 5 wt.% silica containing a dispersant with a surfactant at once, and 5 times each 1 wt. % silica, respectively. Interestingly, a hydrophobic SiO₂ containing nanocomposite membrane showed better electrochemical performance (29% higher than pristine SPAES) despite of low proton conductivity due to its adhesive properties with a catalyst layer in a single cell test. All membranes exhibited better performance comparing to a pristine SPAES membrane.