Book of Abstracts Book of Abstracts - Universität Konstanz

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Single Atom Dispersion of Platinum on Carbon Nanotubes
Yong-Tae Kim 1 , Kazuyoshi Ohshima 1 , Koichi Higashimine 2 , Kazuo Kato 3 , Tomoya Uruga 3 , Keiichi
Osaka 3 , Kenichi Kato 3,4 , Masaki Takada 3,4 , Hiroyoshi Suematsu 3 , Tadaoki Mitani 1
1 School of Materials Science and Center for Nano Materials and Technology, Japan Advanced
2 Institute of Science and Technology (JAIST), 1-1 Asahidai, Tatsunokuchi, Ishikawa 923-1292, Japan
3 Japan Synchrotron Radiation Research Institute (JASRI)/SPring-8, 1-1-1 Kouto, Mikazuki,
Hyogo 679-5198, Japan
4 Core Research for Evolutional Science and Technology, Japan Science Technology Cooperation
(CREST/JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
Electrocatalyst is the key factor to determine the performance of fuel cell. Generally, it is
prepared by the supporting electrocatalytical active material such as platinum on carbon
materials in order to elevate an activity and reduce the usage of novel metal. Carbon supports
therefore affect largely the properties of electrocatalyst such as dispersity, size distribution,
particle shape and intrinsic conductivity. Since the discovery of carbon nanotubes (CNT) in
1991 by Iijima 1 , the application to electrocatalyst supports has been attempted in order to utilize
their superior properties such as good intrinsic conductivity, adequate specific surface area,
accessible surface texture and electrochemical stability. However, there have been also a
limitation that it is difficult to disperse highly and uniformly electrocatalytical active material on
CNT, because they have the inert and plane surface which is difficult to wet in precursor
solution and easy to cause the agglomeration 2 . In order to solve this problem, we adopted the
introduction of thiol groups known to be the functional groups having a good affinity to novel
metal on CNT surfaces. It was expected that high dispersity could be obtained by preventing the
agglomeration among Pt clusters, since surface thiol groups formed the strong bonding with Pt
clusters.
Surprisingly, it was revealed that the surface of thiolated carbon nanotubes was covered with the
mono-layer of single platinum atoms bonded with the surface thiol groups over our expectation.
This phenomenon was confirmed with several analysis tools, such as X-ray Absorption Fine
Structure analysis (EXAFS, XANES), X-Ray Diffractometry (XRD) with synchrotron radiation
of SPring-8, X-ray Photoemission Spectrometry (XPS) and Transmission Electron Microscopy
(TEM).
Here we report the single atom dispersion as the extreme dispersed state of metal and the
possibility to control the cluster size uniformly from single atom.
References
O
Pt
S
NH
C
O
Pt
S
NH
C
Figure 1. Schematic diagram of single Pt atom dispersion on CNT.
[1] S. Iijima, Nature 354, 56 (1991).
[2] E. Dujardin, T. W. Ebbesen, H. Hiura, K. Tanigaki, Science 265, 1850 (1994).
O
Pt
S
NH
C
O
Pt
S
NH
C
O
Pt
S
NH
C