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

Paper SS2-WeM10
Growth and Catalytic Activity of Epitaxial Palladium(111) Films

Wednesday, November 2, 2005, 11:20 am, Room 203

Session: Reactions on Metals & Oxides
Presenter: Z. Dohnalek, Pacific Northwest National Laboratory
Authors: Z. Dohnalek, Pacific Northwest National Laboratory
J. Kim, Pacific Northwest National Laboratory
B.D. Kay, Pacific Northwest National Laboratory
Correspondent: Click to Email
Thin Pd films of various thickness were deposited on FeO(111) and Pt (111) substrates at 40 K. The morphology of the resulting films was characterized using low energy electron diffraction, Auger electron spectroscopy, and Kr and CO temperature programmed desorption as a function of annealing. The Pd layers deposited on Pt(111) are stable and develop into a well ordered Pd(111) films at annealing temperatures ranging from 500 to 1000 K. The Pd films deposited on FeO(111) can be ordered by annealing to 500 K but dewet upon heating to higher temperatures. The efficiency of ethylene hydrogenation was examined on these films as a function of their thickness and surface order. As the Pd(111) film thickness is decreased from 100 to 3 monolayers (ML), only a small increase (1 to 2%) in the hydrogenation efficiency is observed. This implies that H diffusion into the bulk does not play an important role for the films in this thickness range. A dramatic increase in the hydrogenation efficiency, resulting in yields up to 50%, occurs on the films covered with a disordered Pd layer (0-2ML) deposited at 40 K suggesting that the hydrogenation reaction is a structure dependent reaction. @FootnoteText@ Pacific Northwest National Laboratory is operated for the Department of Energy by Battelle under Contract DE-AC06-76RLO 1830.