Synthesis and characterization of highly loaded Pt/carbon xerogel catalysts prepared by the Strong Electrostatic Adsorption method

In order to decrease the mass transport limitations reported in classical PEMFC electrodes, Pt/carbon xerogel catalysts have great potential to replace Pt/carbon black catalysts. These nanostructured materials with well defined pore texture allow for better gas/water diffusion and better contact between the platinum particles and the ionomer (Nafion (R)). Pt/carbon xerogel catalysts with high metal content (similar to 25 wt.%) and high metal dispersion (nanoparticles ca. 2 nm in size) were prepared via the 'Strong Electrostatic Adsorption' method; the impregnation-drying-reduction step with H2PtCl6 was repeated until the desired metal loading was achieved. However, both physicochemical and electrochemical characterization show that the use of H2PtCl6 leads to Pt catalysts poisoned with chlorine, especially if the reduction temperature is lower than 450 degrees C. This induces a dramatic decrease of the Pt utilization ratio in the final PEMFC catalytic layer.