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 $\alpha \text{−}{\mathrm{Al}}_2{\mathrm{O}}_3$, 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.

Figure 1

The orbital-projected DOS plots for the surface Pt atoms for the $\mathrm{Pt}∕{\mathrm{Al}}_T$-alumina system. The shaded regions represent the Pt(111) surface, the solid (—) lines are for the monolayer and the dashed (--) lines are for the bilayer.

Figure 2

Same as Fig. 1, for $\mathrm{Pt}∕{\mathrm{O}}_T$-alumina system.