Abstract: The electrochemical durability of Pt/carbon nanotube (CNT) electrode under potentiodynamic and potentiostatic conditions was investigated. The electrochemical surface area decreased by 18.8% after the electrode was cycled at 0.05～1.2 V for 940 cycles (60 h), while only 5.2% after potentiostatic oxidation at 1.2 V for 60 h. The performance of the Pt/CNT electrode therefore degraded more rapidly under the potentiodynamic condition than that under the potentiostatic condition. X-ray photoelectron spectroscopy analysis showed that the increase in the amount of surface oxygen on the support (multiwalled carbon nanotube) of 1.2 V-oxidized Pt/CNT was more than that on the cyclic voltammetry (CV)-treated one, which indicated that the oxidation degree of MWNT under the potentiostatic condition was higher. X-ray diffraction analysis showed that Pt particle size increased from 3.8 nm to 3.9 and 4.9 nm for 1.2 V-oxidized and CV-oxidized Pt/CNT, respectively. These imply that the increase in Pt particle size, instead of the oxidation of the support, is one of the main reasons for the degradation of Pt/CNT performance.

Key words: platinum, carbon nanotube, fuel cell, electrochemical surface area, durability