Preparation of carbon supported Ru Se based catalysts and their electrochemical performance in DMFC cathodes

Ruthenium catalysts were prepared employing aqueous solutions of ruthenium salts as precursors to obtain 2 nm sized metal particles homogeneously dispersed on a CO2 activa ted carbon support after annealing in hydrogen at 200 C. Selenium treatment was per form ed pouring the reduced product into a H2SeO3 or a SeCl4 solution prior to reduction in hydrogen at 300 C and 800 C. RuSex clusters have been formed which convert into a RuSexOy cluster after exposure to air. The presence of selenium in the cluster surface leads to a significant stabilisa tion against oxi dation of the metallic core and enables a highly selective catalytic activity towards the oxygen reduction reaction. The highest current density in RDE experi ments was observed for a carbon supported Ru 25wt Se 6wt catalyst. Varying metal loading, PTFE and NAFION content in the cathode layer of a DMFC MEA structure, best results were obtained using a metal loading of 1 mg cm2 obtaining power densities of 20 mW cm2 at a cell voltage of 0.4 V in a single cel