Composite proton conducting membranes based on Nafion and sulfonated SiO2 nanoparticles

Sulfonated SiO2 nanoparticles with uniform core–shell structure are synthesized and used as functional fillers for preparing composite proton conducting membranes for direct methanol fuel cells (DMFCs). Poly(4-styrenesulfonic acid) in the shell of SiO2 nanoparticle contributes well-dispersion of the SiO2 nanoparticle in the Nafion membrane. The addition of core–shell SiO2 nanoparticles into Nafion matrix is very effective in improving membrane performance, including ion exchange capacity, proton conductivity, mechanical strength and methanol permeability. As a result, the DMFC assembled with a composite membrane exhibits superior performance as compared to a Nafion-based cell.