The electrochemical stability of carbon black supported and carbon nanotubes supported Pt (Pt/C and Pt/CNTs) electrodes was investigated using potentiostatic oxidation. The oxidation current of Pt/C is about twice of Pt/CNTs. During the 120 h holding at 1.2 V, the electrochemical surface area of Pt decreases 21.3% for Pt/C, but only 7.6% for Pt/CNTs, which implies that degradation rate is more slowly for Pt/CNTs. X-ray photoelectron spectroscopy (XPS) analysis shows that the oxidation degree of carbon black is higher than that of carbon nanotubes, and that the surface chemistry of Pt returns to the initial state after the experiment. It can be concluded that carbon nanotubes are more resistant to electrochemical oxidation than carbon black. Pt/CNTs is more stable than Pt/C. The higher electrochemical stability of Pt/CNTs is attributed to the higher resistance of carbon nanotubes to electrochemical oxidation, but not the change of Pt surface chemistry.

Key words: polymer electrolyte membrane fuel cell, carbon nanotube, stability, electrochemical surface area, resistance to electrochemical corrosion