AVS 50th International Symposium
    Surface Science Thursday Sessions
       Session SS-ThA

Paper SS-ThA1
Atomic Understanding of Strong Nanometer-Thin Metal/Alumina Interfaces and the Making of Nanoscale Island and Film Catalysts

Thursday, November 6, 2003, 2:00 pm, Room 328

Session: Oxide Reactions and Catalysis
Presenter: D.R. Jennison, Sandia National Laboratories
Authors: D.R. Jennison, Sandia National Laboratories
T.R. Mattsson, Sandia National Laboratories
Correspondent: Click to Email
Chambers, Droubay, Jennison, and Mattsson [Science 297 (2002) 827] recently reported room temperature laminar growth of Co deposited in vacuum from an evaporation source on fully hydroxylated but otherwise clean @alpha@-Al@sub 2@O@sub 3@(0001). We extend this work to a number of metals using density functional (DFT) calculations. The exothermicity of the suggested core reaction, 2OH@super -@ + M => H@sub 2@ + 2O@super 2-@ + M@super 2+@, where M represents any metal, is investigated for Cr, Fe, Ni, Cu, Mo, Ru, Rh, Pd, and Al. We find that this reaction is strongly exothermic for most metals. However, while Rh is slightly endothermic, it has a sufficient heat of adsorption to react immediately upon contact. The behavior of Cu cannot be determined within the current accuracy of DFT. Pd is strongly endothermic, suggesting noble metals will not react. By first-principles molecular dynamics simulations of Rh, we confirm a substantial likelihood for direct "hot" reactions driven by the heat of adsorption, as originally proposed. However, Rh has two reaction barriers, indicating more complex kinetics than with Co. Now 1-2 ML films may be made and also nano-islands with steps, both having potential catalysis applications. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000.