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: We describe a facile route to fabricate mesoporous metal oxide (TiO2, CeO2 and ZrO1.95) nanotubes for efficient water retention and migration in a Nafion membrane operated in polymer electrolyte fuel cell under low relative humidity (RH). Porous TiO2 nanotubes (TNT), CeO2 nanotubes (CeNT) and ZrO1.95 (ZrNT) were synthesized by calcining electrospun polyacrylonitrile nanofibers embedded with metal precursors. The nanofibers were prepared using a conventional single spinneret electrospinning technique, under an air atmosphere. Their porous tubular morphology was observed by SEM and TEM analyses. HR-TEM results revealed a porous metal oxide wall composed of small particles joined together. The mesoporous structure of the samples was analyzed using BET. The tubular morphology and outstanding water absorption of the TNT, CeNT and ZrNT fillers resulted in the effective enhancement of proton conductivity of Nafion composite membranes under both fully humid and dry conditions. Compared to a commercial membrane (Nafion, NRE-212) operated under 100 %RH at 80 oC, the Nafion-TNT composite membrane delivered approximately 1.29 times higher current density at 0.6 V. Compared to the Nafion-TiO2 nanoparticles membrane, the Nafion-TNT membrane also generated higher current density at 0.6 V. Additionally, compared to a NRE-212 membrane operated under 50%RH at 80 oC, the Nafion-TNT composite membrane exhibited 3.48 times higher current density at 0.6 V. Under dry conditions (18%RH at 80 oC), the Nafion-TNT, Nafion-CeNT and Nafion-ZrNT composite membranes exhibited 3.4, 2.4 and 2.9 times higher maximum power density, respectively, than the NRE-212. The remarkably high performance of the Nafion-TNT composite membrane was mainly attributed to the reduction of ohmic resistance by the mesoporous hygroscopic metal oxide nanotubes, which can retain water and effectively enhance water diffusion through the membrane.
    ACS Applied Materials & Interfaces 09/2014; · 5.90 Impact Factor
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    ABSTRACT: This review reports on the functions and applications of nanoceramic oxides in proton exchange membrane fuel cells (PEMFCs). Such materials are mainly used as fillers to enhance the water uptake and proton conductivity of polymeric matrices at high temperatures under low relative humidity. To further enhance the mechanical property of proton exchange membranes (PEMs), the functionalized ceramic oxides with organic groups are introduced. Furthermore, the inorganic PEMs are developed to improve their proton conductivities at elevated temperatures. Due to the inherent disadvantages of polymeric PEMs, it is believed that the inorganic PEMs based on porous ceramic oxides are a promising new candidate as solid electrolyte membranes in PEMFCs at high temperatures and with low relative humidity.
    Journal of Nanoscience and Nanotechnology 02/2014; 14(2):1169-80. · 1.34 Impact Factor
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    ABSTRACT: Titanate nanotubes (TiO2-NT) were functionalized with sulfonic acid functional groups and characterized with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Results confirmed that sulfonic acid groups were grafted onto TiO2-NT with a uniform distribution. When the functionalized titanate nanotube (F-TiO2-NT) was incorporated in perfluorosulfonic acid membranes, the membrane conductivity and water uptake were improved. Polymer electrolyte membrane (PEM) fuel cells using 5 wt.% F-TiO2-NT incorporated composite membrane exhibited a peak power density of 429 mW cm–2 with non-humidified O2 at 90 °C, which is about four times higher than that with Nafion 117 membrane at identical conditions. PEMWE with 5 wt.% F-TiO2-NT incorporated composite membrane achieved 1,000 mA cm–2 current density at voltages below 1.6 V at 90 °C without back pressurizing.
    Fuel Cells 12/2013; 13(6). · 1.55 Impact Factor


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Jul 24, 2014