Preparation and testing of Nafion/titanium dioxide nanocomposite membrane electrode assembly by ultrasonic coating technique

ABSTRACT

Membrane 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 cm² active area operating at the temperature range of 70°C to 110°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. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40541.