AVS 51st International Symposium
    Applied Surface Science Thursday Sessions
       Session AS-ThA

Paper AS-ThA8
Carbon Nanotubes and Mo@sub 2@C Reduced Pt Usage for Fuel Cells

Thursday, November 18, 2004, 4:20 pm, Room 210A

Session: Fuel Cell, Catalytic, and Nanomaterials Characterization
Presenter: T. Matsumoto, University of Tsukuba, Japan
Authors: T. Matsumoto, University of Tsukuba, Japan
T. Komatsu, University of Tsukuba, Japan
Y. Chiku, Sekisui Chemical Co., LTD., Japan
Y. Nagashima, University of Tsukuba, Japan
T. Yamazaki, University of Tsukuba, Japan
E. Yoo, University of Tsukuba, Japan
H. Shimizu, Sekisui Chemical Co., LTD., Japan
Y. Sato, Sekisui Chemical Co., LTD., Japan
Y. Takasawa, Sekisui Chemical Co., LTD., Japan
J. Nakamura, University of Tsukuba, Japan
Correspondent: Click to Email
Pt has been considered to be an essential catalyst for the polymer electrolyte fuel cell (PEFC), and one of the difficulties in spreading fuel cells due to the high price, limited resource and no substitute of Pt. We successfully reduce Pt loads by using carbon nanotubes and Mo@sub 2@C. The PEFC with the 0.2 mg/cm@super 2@-Pt/CNT catalyst is fond to show higher cell voltage at 0-600 mA/cm@super 2@ than that of the PEFC with the 0.5 mg/cm@super 2@-Pt/CB catalyst. The PEFC with the only 0.06 mg/cm@super2@-Pt/CNT gives more than 60% of the cell voltage of the PEFC of the 0.5 mg/cm@super 2@-Pt/CB catalyst at 0-600 mA/cm@super 2@. Carbon nanotubes (CNTs) are better electrodes of Pt than carbon blacks (CBs) presumably due to the more triple-phase formation, better conductivity and more space for gas diffusion [J. Nakamura et al., Chem. Comm., 2004, 840 and Catal. Today, in press]. TEM images showed that 2-4 nm Pt nanoparticles are deposited on the CNT surfaces. The Pt nanoparticles from H@sub 2@PtCl@sub 6@ are well-dispersed, while those from K@sub 2@PtCl@sub 4@ are agglomerated due to an auto catalytic reaction. XPS spectra show Pt was fully reduced to be deposited as metallic Pt nanoparticles. The pretreatment of CNTs to remove amorphous carbon is also important, and a careful treatment is necessary for dissolution by HNO@sub 3@ not to form bundles. We also find that Mo@sub 2@C can be a substitute of Pt for PEFC. It is surprising that a PEFC with the Mo@sub 2@C/CNT catalyst in the anode exhibits 60% cell voltages of the current PEFC with the Pt/CB catalyst (0.5 mg/cm@super 2@). XPS and XRD showed that Mo was fully carburized to form Mo@sub 2@C nanoparticles.