Electroreduction of oxygen in polymer electrolyte fuel cells by activated carbon coated cobalt nanocrystallites produced by electric arc discharge

Carbon-coated fee cobalt nanocrystallites produced by the carbon are 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 degrees 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 degrees 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.