Functionalized titania nanotube composite membranes for high temperature proton exchange membrane fuel cells

International Journal of Hydrogen Energy 03/2011; 36(10):6073-6081. DOI:10.1016/j.ijhydene.2011.02.030

ABSTRACT In this study, functionalized titania nanotubes (F-TiO2-NT) were synthesized by using 3- mercaptopropyl-tri-methoxysilane (MPTMS) as a sulfonic acid functionalization agent. These F-TiO2-NT were investigated for potential application in high temperature hydrogen polymer electrolyte membrane fuel cells (PEMFCs), specifically as an additive to the proton exchange membrane. Fourier transform infrared spectroscopy (FT-IR) and X-ray photo- electron spectroscopy (XPS) results confirmed that the sulfonic acid groups were successfully grafted onto the titania nanotubes (TiO2-NT). F-TiO2-NT showed a much higher conductivity than non-functionalized titania nanotubes. At 80 C, the conductivity of F-TiO2-NT was 0.08 S/cm, superior to that of 0.0011 S/cm for the non-functionalized TiO2-NT. The F-TiO2-NT/Nafion composite membrane shows good proton conductivity at high temperature and low humidity, where at 120 C and 30% relative humidity, the proton conductivity of the composite membrane is 0.067 S/cm, a great improvement over 0.012 S/cm for a recast Nafion membrane. Based on the results of this study, F-TiO2-NT has great potential for membrane applications in high temperature PEMFCs.

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    ABSTRACT: Amine-tailored titanate nanotube is introduced to polymer electrolyte membranes for improving the interfacial compatibility between polymeric resin and inorganic materials and enhancing the proton conductivity of the membrane at low relative humidity. Amine-tailored titanate nanotubes are formed through the coupling reaction of surface hydroxyl groups with 3-aminopropyltrimethoxysilane in anhydrous toluene. The grafting density of surface-tailored amino groups reaches 5.19×10−3 mol g−1. Vibrational spectroscopy and X-ray photoelectron spectroscopy confirm that both hydrogen-bonded and free amino groups exist on surface functionalized titanate nanotubes. Polymer electrolyte composite membranes containing the surface functionalized titanate nanotubes and Nafion polymers are characterized for the interfacial compatibility and proton conductivity. The surface grafted amino-groups exhibit positive effect on the interfacial compatibility of polymeric materials and inorganic materials, resulting in increased yield strength of composite membranes. At 100° C and 50% relative humidity, the proton conductivity of the formed composite membrane impregnated with functionalized titanate nanotubes reaches 0.045 Scm−1 that is about 4–5 times higher than that of pristine Nafion membrane and 3 times higher than that of composite membrane impregnated with unmodified titanate nanotubes.
    Journal of Membrane Science s 423–424:284–292. · 4.09 Impact Factor
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    Ionics 19(7). · 1.67 Impact Factor