Novel modification of Nafion®117 for a MEMS-based micro direct methanol fuel cell (μDMFC)

Nowadays the micro direct methanol fuel cell (μDMFC) has received much attention as a leading candidate for portable power of the future. This paper presents a novel modification method of the commercial proton exchange membrane Nafion117 to produce an improved polymer electrolyte membrane for the μDMFC. The method involves using γ-ray radiation and electroless palladium deposition on a Nafion117 membrane. Specific scopes of the γ-ray radiation dose may cause membrane crosslinking, thus reduce the membrane swelling ratio and decrease methanol crossover. The electroless palladium deposition on the γ-ray radiation modified Nafion117 further decreases methanol crossover. The modified membrane was characterized using a scanning electron microscope (SEM), an energy dispersive x-ray spectrometer (EDX) and x-ray diffraction (XRD). Water uptake, methanol permeability and membrane conductivity tests were also carried out. By reducing the membrane swelling ratio and methanol permeation, the single μDMFC with the modified Nafion117 membrane produced reasonable power density performance as high as 4.9 mW cm ^-2 under 2 M methanol solution at room temperature.