In Situ Fabrication of Nafion–Titanate Hybrid Electrolytes for High-Temperature Direct Ethanol Fuel Cell

The synthesis and characterization of a novel Nafion-matrix nanocomposite by the in situ conversion of titania particles into titanate nanofilaments such as nanotubes and nanorods are reported. Titania nanoparticles grown inside Nafion hydrophilic domains were converted by a microwave-assisted hydrothermal reaction into the proton conducting titanate nanotubes and nanorods. Detailed characterization by Raman spectroscopy, X-ray diffraction, small-angle X-ray scattering, and transmission electron microscopy evidenced an intimate interaction between titanate nanostructures and the ionomer hydrophilic phase. The favored localization of such high aspect ratio nanofilaments in the ionic phase of Nafion has a marked impact on the properties of the composites. The experimental data showed enhanced mechanical stability at high temperature (∼130 °C) that was correlated to a strong temperature dependence of the proton conductivity in the same temperature range. Such properties contributed to a significant increase of the performance of direct ethanol fuel cells operating at high temperature (∼130 °C) using hybrid Nafion–titanate electrolytes compared to commercial Nafion.