Nano-TiO₂-coated polymer electrolyte membranes for direct methanol fuel cells

Composite polymer electrolyte membranes with nano-TiO₂ films are fabricated by deposition of titania nanoparticles from a sol solution. Measurements of ion conductivity, methanol permeability and single-cell performance of the modified Nafion membranes are conducted. The TiO₂ films adhere well and are crack-free. The protonic conductivity of the composite membranes decreases with increasing titania content, but methanol permeability is reduced. Preliminary tests on a single-cell of a direct methanol fuel cell (DMFC) indicate that a titania-coated membrane with 0.009 mg cm^-2 content gives the highest cell voltage and maximum power density.