Sulfonated silica-based fuel cell electrode structures for low humidity applications

Ceramic carbon electrodes (CCEs) are prospective candidates for use in proton exchange membrane fuel cells due to their high surface area, water retention properties, and durable nature. We have determined that incorporating small amounts of sulfonated silane in the CCE structure can lead to a profound enhancement of catalytic activity and proton conductivity. To evaluate the usefulness of a new catalyst layer for practical use, performance of the materials under various conditions must be considered. We have compared the properties of membrane electrode assemblies (MEA) prepared with CCE cathode catalyst layers to that of an MEA prepared with Nafion-based cathode catalyst layers. The MEAs were characterized via transmission electron microscopy, thermogravimetric analysis, infrared spectroscopy, and BET analysis. Fuel cell performance using different cathode gas relative humidity (RH) feed conditions was monitored using electrochemical impedance spectroscopy and polarization curves. Our CCE cathode materials maintained stable performance and had improved water management capabilities at low relative humidities, whereas Nafion-containing cathodes have performed poorly. The enhanced performance and tolerance to low RH is explained in terms of water retention within the CCE-based MEA. (C) 2013 Elsevier B.V. All rights reserved.