Supported metal electronic structure: Implications for molecular adsorption

Using ab initio methods, we examine the electronic structure of substrate-supported metal films. We predict a coexistence between charge-transfer valence-bond states and bandlike metallic states. The role of the support composition in determining the balance of bond and band states is elucidated for Pt on Al- and O-terminated alpha-Al2O3, and we reveal how this coexistence evolves with metal film thickness. Using CO chemisorption as a probe of metal film electronic structure, we demonstrate that this combination of bond and band effects leads to significant changes in surface chemistry.