(324a) DFT and Parameterized-Model Studies On the Reactivity of Heterogeneous Catalyst Surfaces: Alloying and Coverage Effects

The surface electronic structure is the key factor determining the activity and selectivity of many late transition metals. Understanding how the surface electronic structure varies due to alloying and adsorbate coverage effects is essential to understanding the variations in chemical reactivity among adsorbate covered alloy surfaces. We have developed a simple tight-binding model that accounts for changes in the surface electronic structure due to the presence of adsorbates and/or due to alloying. Here, we present a tight-bonding approach parameterized by a database of density functional theory calculations to model the effects of simple adsorbates (C,N, O and S) and alloying on the surface d-bands of the late transition metals. The model includes the combined effects of electronic and geometric contributions as well as the coverage dependences in adsorption energies. We discuss how our model could be used in conjunction with DFT calculations to rapidly screen a broad range of structures to identify surfaces with desirable electronic and thus chemical properties.