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Article Citation - WoS: 31Citation - Scopus: 35Preparation and Testing of Nafion/Titanium Dioxide Nanocomposite Membrane Electrode Assembly by Ultrasonic Coating Technique(Wiley-blackwell, 2014) Devrim, Yilser; Alemdaroğlu Temel, Mine; Alemdaroğlu Temel, MineMembrane electrode assemblies with Nafion/nanosize titanium dioxide (TiO2) composite membranes were manufactured with a novel ultrasonic-spray technique (UST) and tested in proton exchange membrane fuel cell (PEMFC). The structures of the membranes were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis. The composite membranes gained good thermal resistance with insertion of TiO2. The SEM and XRD techniques have proved the uniform and homogeneous distribution of TiO2 and the consequent enhancement of crystalline character of these membranes. The existence of nanometer size TiO2 has improved the thermal resistance, water uptake, and proton conductivity of composite membranes. Gas diffusion electrodes were fabricated by UST. Catalyst loading was 0.4 (mg Pt) cm(-2) for both anode and cathode sides. The membranes were tested in a single cell with a 5 cm(2) active area operating at the temperature range of 70 degrees C to 110 degrees C and in humidified under 50% relative humidity (RH) conditions. Single PEMFC tests performed at different operating temperatures indicated that Nafion/TiO2 composite membrane is more stable and also performed better than Nafion membranes. The results show that Nafion/TiO2 is a promising membrane material for possible use in PEMFC at higher temperature. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40541.Article Citation - WoS: 44Citation - Scopus: 43Fabrication and Performance Evaluation of Hybrid Membrane Based on a Sulfonated Polyphenyl Sulfone/Phosphotungstic Acid/Silica for Proton Exchange Membrane Fuel Cell at Low Humidity Conditions(Pergamon-elsevier Science Ltd, 2014) Devrim, YilserSulfonated polyphenyl sulfone/phosphotungstic acid/silica ( sPPS/PWA/silica) hybrid membranes were prepared and characterized as alternative materials for PEMFC operation at high temperature and low humidity conditions. Polyphenyl sulfone polymer (PPS) was sulfonated with trimethylsilyl chlorosulfonate in 1,2 dichloroethane at ambient temperatures. The degree of sulfonation was determined by 1H-NMR analysis. Sulfonation levels from 25 to 45% were easily achieved by varying the content of the sulfonation agent. The hybrid membrane was composed of the mixture of sPPS solution, PWA/silica particles. The structures of the membranes were investigated by Scanning Electron Microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and by thermogravimetric analysis (TGA). The composite membranes gained good thermal resistance with insertion of PWA/silica. SEM results have proven the uniform and homogeneous distribution of PWA/silica in hybrid membrane. The existence PWA/silica has improved the water uptake, proton conductivity and oxidative stability of hybrid membrane. Gas diffusion electrodes (GDE) were fabricated by ultrasonic coating technique. Catalyst loading was 0.4 mg Pt/cm(2) for both anode and cathode sides. The membranes were tested in a single cell with a 5 cm(2) active area operating at the temperature range of 70 to 120 degrees C and 100 and 30% relative humidity conditions. Single PEMFC tests performed at different operating temperatures indicated that sPPS/PWA/silica hybrid membrane was more stable and also performed better than pristine sPPS membrane. At the overall, the sPPS/PWA/silica hybrid membrane seems to be a promising alternative membrane for the possible utilization in PEMFC. (C) 2014 Elsevier Ltd. All rights reserved.
