AVS 50th International Symposium
    Surface Science Friday Sessions
       Session SS1-FrM

Paper SS1-FrM3
Chemical Properties of Bimetallic and Metal Carbide Surfaces by Theoretical and Experimental Studies

Friday, November 7, 2003, 9:00 am, Room 327

Session: Catalysis IV: Reactivity of Complex Systems
Presenter: J.R. Kitchin, University of Delaware
Authors: J.R. Kitchin, University of Delaware
M.A. Barteau, University of Delaware
J.G. Chen, University of Delaware
Correspondent: Click to Email
The optimal catalyst balances the adsorption energies of all surface species involved, ensuring adequate concentrations of important intermediates, while preventing poisoning by strongly bound intermediates. Multi-component catalysts, such as transition metal carbides and bimetallic catalysts, are one solution to these problems, as the adsorption properties of molecules can be tuned by the composition of the catalyst. However, it is difficult to know a priori how the chemical properties of a particular carbide or bimetallic catalyst will be modified relative to the parent metals. Advances in Density Functional Theory (DFT) now allow many of these systems to be explored from first principles with desktop computers. We have used DFT to calculate electronic properties and adsorption energies of small molecules and atoms on idealized bimetallic and carbide catalyst surfaces. These electronic properties were then used to establish correlations with experimental data and the calculated adsorption energies. For example, we calculated the electronic structure and adsorption energy of H atoms (HBE) on 13 different monolayer, bimetallic catalyst surfaces and showed a near linear correlation between the calculated HBEs and the surface d-band center of the catalyst. We have calculated the surface d-band centers of more than 25 other monolayer, bimetallic combinations and some carbide surfaces. Using the HBE/d-band correlation established above we could use these calculations to predict promising new bimetallic catalysts with desirable H and CO binding energies. These correlations, along with a growing database of calculated d-band centers for bimetallic and carbide catalysts, should be considered a starting point for the rational design of bimetallic and carbide catalysts with desired chemisorption properties.