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

Paper SS1+EM-MoA2
Influence of Surface Reactions on Morphology: Ag Nanoclusters on TiO@sub 2@(110)

Monday, October 25, 1999, 2:20 pm, Room 606

Session: Metals on Oxides
Presenter: X. Lai, Texas A&M University
Authors: X. Lai, Texas A&M University
T.P. St. Clair, Texas A&M University
D.W. Goodman, Texas A&M University
Correspondent: Click to Email
The effects of in situ O@sub 2@ exposure on TiO@sub 2@(110)-supported Ag nanoclusters were investigated using x-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). An oxygen-induced cluster ripening was observed by STM after exposing Ag/TiO@sub 2@(110) to 10.00 Torr O@sub 2@ in an elevated-pressure reactor. A bimodal size distribution of Ag clusters was evident after a 10 minute O@sub 2@ exposure at room temperature. Time-dependent studies of the ripening process indicated that the majority of the ripening occurred within the first hour of exposure. The cluster density also increased 5-15%, indicating that redispersion simultaneously occurred with ripening. For comparison, a reduced, roughened TiO@sub 2@(110) and a fully oxidized TiO@sub 2@(110) were prepared and used as Ag supports. Propylene exposure was also studied to further investigate adsorbate-induced morphological changes. Issues relevant to the stability of Ag catalysts for general oxidation reactions were addressed.