Abstract: The nano-scale Pt-CeO₂/C catalyst was prepared by the co-precipitation method. The results of transmission electron microscopy and X-ray diffraction analysis show that the average size of Pt-CeO₂/C noble metal particles (1.5~2.5 nm) is highly dispersed on the carbon supports. Pt-CeO₂/C and a commercial Pt/C catalyst from Johnson Matthey Company were investigated by cyclic voltammetry and CO-stripping experiment. The cyclic voltammetry test shows that the Pt-CeO₂/C catalyst has similar electrochemical surface area to Pt/C, which indicates that the home-made Pt-CeO₂/C catalyst has high electrocatalytic activity for hydrogen oxidation. From the CO-stripping experiment, the Pt-CeO₂/C catalyst showed very high CO tolerant activity compared to the Pt/C catalyst. We also fabricated the membrane electrode assembly with Pt-CeO₂/C or Pt/C catalyst on the anode (the cathode also used the Pt/C catalyst) and found that Pt-CeO₂/C catalyst showed higher performance than Pt/C catalyst. A tentative mechanism was proposed for a possible role of Ce as a co-catalyst in the Pt/C system for CO electrooxidation.

Key words: proton exchange membrane fuel cell, carbon monoxide tolerance, platinum, ceria, electrochemical surface area, carbon monoxide-stripping