AVS 52nd International Symposium
    Surface Science Wednesday Sessions
       Session SS2-WeA

Paper SS2-WeA5
The Active Structure of Supported Au Catalysts

Wednesday, November 2, 2005, 3:20 pm, Room 203

Session: Reactions on Nanoclusters
Presenter: M.S. Chen, Texas A&M University
Authors: M.S. Chen, Texas A&M University
Z. Yan, Texas A&M University
Y. Cai, Texas A&M University
W.T. Wallace, Texas A&M University
X.F. Lai, Texas A&M University
D.W. Goodman, Texas A&M University
Correspondent: Click to Email
The high catalytic activity of gold clusters on oxides has been attributed to structural effects, including particle thickness and shape, metal oxidation state, as well as support effects. The best catalytic performance of supported Au particles was found for clusters with sizes of 2~3 nm. For Au clusters supported on TiO2(110), the unique properties have been associated with Au structures two atomic layers in thickness based on STM and kinetic measurements (M. Valden, X. Lai, D. W. Goodman, Science 281, 1647 (1998)), and confirmed by our recent results. Specifically, we have synthesized well-ordered Au monolayers [(1x1)] and bilayers [(1x3)] that completely wet (cover) the oxide support [a titanium oxide monolayer film grown on the Mo(112) surface] (M. S. Chen, D. W. Goodman, Science 306 (2004) 252.). Kinetic measurements for CO catalytic oxidation show that the Au bilayer structure is significantly more active (by more than an order of magnitude) than the monolayer strucuture, and is approximately 45 times higher than that reported for the most active high-surface-area Au/TiO2 catalysts. These specific rates clearly indicate that bilayer Au is the active structure for CO oxidation. These results eliminate particle shape and direct support effects as significant contributions to the special catalytic properties of nano-sized Au clusters.