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Nanoscale characterization of Pd/TiO2 catalysts and Ag/TiO2 catalysts by electron holography

Published online by Cambridge University Press:  01 February 2011

Satoshi Ichikawa
Affiliation:
ichikawa@nano.sigma.es.osaka-u.ac.jp, Osaka University, Organization for the Promotion of Research on Nanoscience and Nanotechnology, 1-1-H329, Machikaneyama, Toyonaka, Osaka, 560-0043, Japan, +81-6-6850-5754, +81-6-6850-5754
Tomoki Akita
Affiliation:
t-akita@aist.go.jp, National Institute of Advanced Industrial Science and Technology (AIST), Research Institute for Ubiquitous Energy Devices, Japan
Kazuyuki Okazaki
Affiliation:
k.okazaki@aist.go.jp, National Institute of Advanced Industrial Science and Technology (AIST), Research Institute for Ubiquitous Energy Devices, Japan
Koji Tanaka
Affiliation:
koji.tanaka@aist.go.jp, National Institute of Advanced Industrial Science and Technology (AIST), Research Institute for Ubiquitous Energy Devices, Japan
Masanori Kohyama
Affiliation:
m-kohyama@aist.go.jp, National Institute of Advanced Industrial Science and Technology (AIST), Research Institute for Ubiquitous Energy Devices
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Abstract

Catalytic properties of noble metal catalysts are often caused by their nanostructures and the interaction between nano particles and oxides supports. We examine the mean inner potential of Pd particles in Pd/TiO2 catalyst and Ag particles in Ag/TiO2 catalysts using electron holography and HRTEM. And we compare the results of the Pd/TiO2 and Ag/TiO2 systems with our previous results of the Au/TiO2 and Pt/TiO2 systems. In the case of the Pd/TiO2 catalysts, when the size of Pd particle is smaller than 5nm, the mean inner potential of Pd changes to be higher than the calculated value of the mean inner potential which is thought to be higher than the experimental values of bulk Pd by 3-5V. The mean inner potential of Pd becomes to increase gradually as the size of the Pd particle decreases. The rate of the increment in the mean inner potential of Pd is lower than that of Au/TiO2 catalysts and Pt/TiO2 catalysts. On the other hand, in the case of Ag/TiO2 catalysts, the mean inner potential of Ag does not increase though the size of the Ag particle decreases to under 2nm.

Type
Research Article
Copyright
Copyright © Materials Research Society 2006

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