Development and electrochemical studies of ruthenium nanoparticles as cathode in a PEMFC

摘要

The molecular oxygen reduction reaction was investigated on nanoparticles of ruthenium in 0.5M H2SO4. The electrocatalyst was synthesized by reacting the ruthenium carbonyl compound, Ru-3(CO)(12), in 1,6-hexanediol (b.p. approximate to 250 degreesC), under refluxing conditions for two hours. The electrocatalyst presents an agglomeration of particles with a nanometric size and high uniformity. Conventional Tafel analysis of the data shows that the reaction order with respect to oxygen is unity and an independent variation of the Tafel slope with temperature. The dependence of temperature on the kinetic parameters was studied and the entropic component of the transfer coefficient was found to play one of the most important roles in the electrocatalytic reaction. The apparent activation energy was evaluated in a temperature range of 298-338 K. Performance achieved from the H-2/O-2 PEM single cell at 80 degreesC, with cathode of Ru-x was compared with electrodes of platimum in a membrane electrode assembly. We assume that the intrinsic properties of the Rux electrocatalyst cause the variation between the electrochemical Tafel behavior and the performed as a cathode electrode in a membrane electrode assembly.