| AVS 55th International Symposium & Exhibition | |
| Surface Science | Thursday Sessions |
| Session SS2-ThA |
| Session: | Novel Reactive Surfaces |
| Presenter: | T. Kondo, University of Tsukuba, Japan |
| Authors: | T. Kondo, University of Tsukuba, Japan K. Watahiki, University of Tsukuba, Japan J.P. Oh, University of Tsukuba, Japan K. Izumi, University of Tsukuba, Japan Y. Iwasaki, University of Tsukuba, Japan D. Sekiba, University of Tsukuba, Japan H. Kudo, University of Tsukuba, Japan J. Nakamura, University of Tsukuba, Japan |
| Correspondent: | Click to Email |
Catalytic activity and surface morphology of Pt vapor-deposited on highly oriented pyrolytic graphite (HOPG) have been investigated by hydrogen-deuterium exchange reaction, scanning tunneling microscopy (STM), temperature programmed desorption (TPD) of CO and in-situ measurement of helium atom scattering (HAS). Based on the STM observation, Pt particles deposited on HOPG with sub-monolayer coverage at room temperature are found to form mostly monolayer clusters on a graphite surface with the reduction in the nearest-neighbor atomic distance of the platinum atoms by as much as 13 % compared to that of the single crystal platinum. Turn over frequency of the hydrogen-deuterium exchange reaction at 24 Torr and 340 K is found to be one order magnitude higher for the monolayer Pt cluster than three-dimensional Pt cluster at 340 K, indicating the smaller adsorption energy of hydrogen on the Pt monolayer cluster. Based on the TPD experiment of CO from Pt/HOPG, the similar catalytic property is found for the monolayer Pt cluster: lower binding energy of CO with Pt compare to the case on the single crystal platinum. These specific catalytic activities are however found to be lost by the slight annealing of Pt/HOPG above 350 K. The change in the catalytic activity is attributed to the change in the morphology of the Pt cluster from monolayer to three-dimensional phase based on the HAS and STM measurements. The higher specific catalytic activity for the Pt monolayer cluster will be discussed in terms of the interface interaction between Pt atoms and the graphite surface.