Study of IrxMny(CO)n(DMF)z as Electrocatalyst for Oxygen Reduction and Hydrogen Oxidation in the Presence of Fuel Cell Contaminants

Abstract

The oxygen reduction reaction (ORR) and the hydrogen oxidation reaction (HOR) have been studied on a wide range of elec-trocatalysts, including bimetallic materials which are based solely on platinum group metals and their alloys. This work reports the synthe-sis and characterization of a novel bimetallic electrocatalyst, IrxMny(CO)n(DMF)z, for the ORR and HOR in acid media. The material was synthesized by reacting Ir4(CO)12 and MnCl2·4H2O in DMF. It was characterized structurally by FT-IR and micro-Raman spectroscopy, X-ray diffraction, SEM and energy-dispersive X-ray spectroscopy; the electrochemical characterization was made by the rotating disk elec-trode technique, at room temperature. The electrocatalytic activity of the new material for the ORR and HOR does not show appreciable variations due to the presence of methanol or carbon monoxide, respectively, even at high concentrations of these contaminants (2 mol L-1 methanol and 0.5% CO). This tolerance is a very important property with respect to platinum-based catalysts, which are poisoned by low concentrations of such contaminants. The kinetic parameters of the novel catalyst, such as Tafel slope (b), exchange current density (jo) and charge transfer coefficient (α), are reported as well. The results show that the novel electrocatalyst is attractive for evaluation as cath-ode/anode in PEM fuel cells.