Composite silica/Nafion® membranes prepared by tetraethylorthosilicate sol–gel reaction and solution casting for direct methanol fuel cells

Composite silica/Nafion® membranes were prepared using a tetraethylorthosilicate (TEOS) hydrolysis sol–gel reaction followed by solution casting. Physico-chemical properties of the composite membranes were characterized by TGA, XRD, FT-IR, SEM-EDX and water uptake. Membranes were investigated in direct methanol fuel cells (DMFCs). Lower silica loadings (3 and 5 wt.%) in the composite membranes helped to inhibit methanol crossover through the membrane, while higher silica loadings demonstrated a smaller contribution to lowering the methanol crossover. Proton conductivity of the composite membranes decreased with increasing silica content, in spite of the increasing membrane water uptake. DMFC performance using the composite membrane with 5 wt.% silica loading was higher than using a pure Nafion® membrane.