AVS 53rd International Symposium
    Surface Science Monday Sessions
       Session SS1-MoA

Paper SS1-MoA8
Electrode Catalysts of Polymer Electrolyte Fuel Cell using Carbon Nanotube

Monday, November 13, 2006, 4:20 pm, Room 2002

Session: Catalysis for the Hydrogen Economy
Presenter: J. Nakamura, University of Tsukuba, Japan
Authors: J. Nakamura, University of Tsukuba, Japan
E. Yoo, University of Tsukuba, Japan
T. Watanabe, University of Tsukuba, Japan
Correspondent: Click to Email
The high-priced and limited Pt constitutes a high barrier to commercialization of fuel cells. Pt is essential for the electrode catalyst of polymer electrolyte fuel cells (PEFCs). Reduction in Pt usage is one of the key requirements for the commercialization of fuel cells for use in everyday life, because of its high price and limited availability, and the difficulty of finding suitable substitutes. We have reported that use of carbon nanotube (CNT) as an electrode material results in high performance with low loading of Pt. That is, the electric power of 12 wt% Pt/CNT was found to be higher than that of 29wt% Pt/carbon black. This is due to efficient formation of triple phase boundary (electrode/electrolyte/gas). Recently, we observed that Ru/Pt/CNT shows higher tolerance for CO poisoning compared to Ru/Pt/carbon black. This suggests that the interface between carbon and alloy catalysts is very different so that the Ru-Pt alloy phase is modified in terms of catalytic nature. The shape of metal catalyst particles is elongated on CNT surfaces, while catalysts on carbon black or defected carbon surfaces is spherical. This is the consequence of the difference in the state of the interface. In general, the electric double layer is formed at the interface between metallic surfaces, where electrons flow from materials with low work function to those with high work function. The electric double layer causes attractive interaction at the interface. The observed support effect of CNT is ascribed to the strong interaction between flat graphene sheet and Pt-Ru alloy particles, leading to the modification of catalytic nature. In this presentation, we report and discuss the effect of carbon surface below metal catalysts upon the performance of electrode catalysts by showing the results of CNT supported electrode catalysts and model system of metal catalysts/HOPG (Highly oriented pyrolytic graphite).