Chromium-based electrocatalysts for oxygen reduction in polymer electrolyte fuel cells

A catalyst for oxygen reduction in polymer electrolyte fuel cell is obtained when chromium hydroxide, CF(OH)(3), adsorbed on carbon black is pyrolyzed at 1000 degrees C in Ar containing acetonitrile vapors. The Cr loading of the carbon black was 7.3 +/- 0.4 wt%. Single cell life test experiments at 0.5V and 50 degrees C indicate that after 300h, the catalyst looses about 20% of its original current density (0.14 A/cm(2)). X-ray diffraction indicates that the metal is present as a chromium carbide nitride. This result is confirmed by X-ray photoelectron spectroscopy. Cr carbide nitride nanoclusters covered with a N-containing carbonaceous material ale visible by Transmission Electron Microscopy. They are, however, not necessary associated with the catalytic site for O-2 reduction. No catalytic activity is observed when Cr(OH)(3) adsorbed on carbon black is pyrolyzed at 1000 degrees C in Ar.