Electroreduction of Oxygen in Polymer Electrolyte Fuel Cells by Activated Carbon Coated Cobalt Nanocrystallites Produced by Electric Arc Discharge

Carbon-coated fcc cobalt nanocrystallites produced by the carbon arc method have practically no activity as catalysts for O 2 reduction in H 2 /O 2 polymer electrolyte fuel cells. This material, containing 17.0 wt % Co, was activated by a pyrolysis step at 1000 °C in Ar containing acetonitrile vapor. When it was used at the cathode of a single fuel cell element, it provided an initial current of 0.10 A/cm 2 mg of Co at 0.5 V and 50 °C. This current decreased by 40% after 300 h. Only a fraction of the carbon-coated metal in the initial material was activated by the pyrolysis treatment. XPS and TEM characterizations were performed on the catalyst at various stages of its preparation.