AVS 46th International Symposium
    Surface Science Division Monday Sessions
       Session SS1+EM-MoA

Paper SS1+EM-MoA5
Nucleation and Growth of Pt Nanoclusters on TiO@sub 2@ Rutile and Anstase Surfaces

Monday, October 25, 1999, 3:20 pm, Room 606

Session: Metals on Oxides
Presenter: Y. Liang, Pacific Northwest National Laboratory
Authors: Y. Liang, Pacific Northwest National Laboratory
A.W. Grant, University of Washington
D.R. Baer, Pacific Northwest National Laboratory
S. Gan, Pacific Northwest National Laboratory
Correspondent: Click to Email
Understanding the interaction of ultra-thin metal overlayers with oxide surfaces impacts a wide range of technological applications. One of those is the oxide-supported metal catalysts where unusual surface chemisorption and activity have been observed. In this presentation, we report an investigation of nucleation and growth of Pt on rutile and anatase surfaces using scanning tunneling microscopy, x-ray photoelectron spectroscopy, and low energy electron diffraction. Results show that vapor deposition of 0.1 ML of Pt on a rutile TiO@sub 2@(110) surface at ambient temperature leads to the formation of randomly distributed three-dimensional Pt nanoclusters on the 1x1 surface. However, this random distribution is strongly perturbed by the presence of surface line defects produced by extended sputtering and annealing cycles. As the density of the line defect increases, majority of Pt nanoclusters are preferentially attached at the ends of line defects instead of randomly distributed on the rutile surfaces. This result suggests that the line defects on TiO@sub 2@(110) surfaces have stronger interaction with Pt and thus serve as nucleation sites for Pt growth. Based on the change of distribution of Pt clusters as a function of line defect density, the diffusion length of Pt on rutile surfaces is obtained. In addition to rutile, we also investigate the nucleation and growth of Pt on anatase surface. We have successfully grown anatase single crystal thin films on SrTiO@sub 3@ substrates using oxygen plasma assisted molecular beam epitaxy. Investigation of nucleation and growth of Pt on anatase surface is currently in progress. The results will be presented at the meeting and compared with those obtained on the rutile TiO@sub 2@ surfaces.