Preparation of Carbon Supported Ru-Se Based Catalysts and their Electrochemical Performance in DMFC Cathodes

Abstract

Ruthenium catalysts were prepared employing aqueous solutions of ruthenium salts as precursors to obtain 2 nm sized metal particles homogeneously dispersed on a CO2-activated carbon support after annealing in hydrogen at 200 {degree sign}C. Selenium treatment was performed pouring the reduced product into a H2SeO3 or a SeCl4 solution prior to reduction in hydrogen at 300 {degree sign}C and 800 {degree sign}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 oxidation of the metallic core and enables a highly selective catalytic activity towards the oxygen reduction reaction. 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 cell.