COLL 134 |
| The particle size effect of carbon-supported Pt nanoparticles on the electrocatalytic activity has been a controversial issue for both the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) in fuel cell applications. The electrocatalytic activity of Pt nanoparticles has been shown to depend on geometric effect (density of edge and kink sites), electronic effect (d bend center energy with respect to the Fermi level) and carbon support effect. The discrepancies can be caused by the different amount of Pt loading on carbon support as well as the complex pore structure of activated carbon. To elucidate this controversial issue, we have approached it with supported Pt nanoparticles with particle size (1nm to 5nm) using a constant amount of Pt on flat multi-wall carbon nanotubes or high surface area carbon. The valence band and surface atomic structures of Pt nanoparticles are examined using photoelectron spectroscopy and high-resolution transmission electron microscopy, respectively. In this paper, we discuss in detail how the electronic structure and surface atomic structure of Pt nanoparticles may influence the ORR and MOR activity. |
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Electrochemistry-Enabled Nano S&T
2:00 PM-5:00 PM, Monday, April 7, 2008 Morial Convention Center -- Rm. 227, Oral
Division of Colloid & Surface Chemistry |