AVS 45th International Symposium
    Surface Science Division Monday Sessions
       Session SS-MoP

Paper SS-MoP14
Characterization of CO Oxidation over Au/TiO@sub 2@(110) by Scanning Tunneling Microscopy

Monday, November 2, 1998, 5:30 pm, Room Hall A

Session: Surface Science Division Poster Session
Presenter: X. Lai, Texas A&M University
Authors: X. Lai, Texas A&M University
M. Valden, Texas A&M University
D.W. Goodman, Texas A&M University
Correspondent: Click to Email
Au clusters of 1-6 nm in diamteter were vapor deposited onto a TiO@sub 2@(110)-(1x1) single crystal under ultrahigh vacuum (UHV) condition, monitored by Auger Electron Spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). Fresh Au clusters on TiO@sub 2@(110) were transferred in situ into a high pressure cell, then exposed in separate experiments to 10 torr CO:O@sub 2@ (2:1), CO and O@sub 2@. STM observed the morphology change of Au clusters induced by reaction mixtures at 300 K, indicating the chemisorption of O@sub 2@ on Au clusters and TiO@sub 2@ substrate even at room temperature. The maximum activity for the oxidation of CO on Au/TiO@sub 2@ is obtained with Au clusters less than 3.5 nm in diameter and 1.0 nm in height (~300 atoms/cluster) exhibiting an electronic structure characterized by a band gap in the range of 0.2 V - 0.6 V as measured by STM and scanning tunneling spectroscopy (STM/STS), which suggests that CO oxidation over Au/TiO@sub 2@ is structure sensitive.