Preparation and Characterization of an Oxidized MWCNT-Reinforced Nafion<SUP>®</SUP> Nanocomposite Membrane for Direct Methanol Fuel Cell

Abstract

Oxidized multiwalled carbon nanotube (MWCNT) reinforced Nafion ® nanocomposite membranes were prepared toward the use a polymer electrolyte membrane (PEM) for direct methanol fuel cells. To reduce methanol crossover through Nafion ® membrane, the oxidized MWCNTs were prepared and added into the Nafion ® membrane in the range of 0.5―3 wt%. The oxidized MWCNTs were prepared by treatment with 60% nitric acid at 120 ° C for 12 h and characterized by scanning electron microscope and Raman spectroscopy. Well-aligned structures with low entanglement were observed in the oxidized MWCNTs. The portion of amorphous carbon structure in the oxidized MWCNTs was increased by the oxidation reaction. The oxidized MWCNT reinforced Nafion ® nanocomposite membranes were prepared by a solution casting method on a hot plate. Thermal stability was enhanced by adding MWCNT into Nafion ® membranes. While MWCNT-reinforced Nafion ® nanocomposite membranes exhibited similar ion exchange capacity to that of Nafion ® , the methanol uptake was reduced about 14 wt%.