Composite Membrane Based on SiO2-MWCNTs and Nafion for PEMFCs

A novel composite membrane for fuel cell applications was prepared by incorporating custom-made silica-coated multi-wall carbon nanotubes (SiO2-MWCNTs) in Nafion resin. The MWCNTs were used to provide mechanical reinforcement to the Nafion polymer. The SiO2 coating on the surface of the MWCNTs helped to electrically insulate the MWCNTs from each other and inhibit electron transport across the thickness of the membrane. Additionally, the highly hygroscopic SiO2 enhanced water absorption and retention in the membrane which improves fuel cell performance under low relative humidity conditions. Transmission electron microscopy confirmed the formation of the SiO2-MWCNTs particles. The electrical resistivity of the composite membrane was tested by the four-point probe method and compared with pure Nafion and MWCNT/Nafion membranes. Tensile strength, water uptake and swelling of the membranes were also measured and compared at 60 degrees C. The polarization curves at 50% relative humidity clearly indicated that the fuel cell performance of the novel SiO2-MWCNT/Nafion composite membrane was significantly better than that of the pure Nafion membrane. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.079208jes]