Durability of carbon-silica supported catalysts for proton exchange membrane fuel cells

Carbon-aerogel silica composite material is evaluated as an alternative catalyst support material for Proton Exchange Membrane (PEM) fuel cells. Brunauer-Emmett-Teller surface areas of these materials are usually higher than Vulcan XC-72 which enabled a homogeneous catalyst distribution. Performance of the Membrane Electrode Assemblies (MEAs) prepared with C-SiO ₂ supported platinum catalysts increased with low silica content and decreased at higher levels. Performances up to 0.31 W cm ^-2 at 0.8 V are obtained with silica containing MEAs whereas only 0.23 W cm ^-2 at 0.8 V could be obtained with silica free MEAs. On the other hand, durability of the MEAs increased with increasing silica content. Accelerated durability tests show a current drop of 22-40% (at 0.6 V) for silica containing MEAs compared to 40% (at 0.6 V) for silica-free MEAs. Although appearing to have improved durability, silica containing MEAs show hydrophilic behavior, especially at high current density.