Invited Paper SS1-TuA4
General Trends in the Electronic and Chemical Properties of Monolayer Bimetallic Surfaces

Tuesday, October 16, 2007, 2:40 pm, Room 608

It is well known that bimetallic surfaces often show novel properties that are not present on either of the parent metal surfaces. The modification effect is especially important at the admetal coverages in the submonolayer and monolayer regime. However, it is difficult to know a priori how the chemical properties of a particular bimetallic surface will be modified relative to the parent metals. We have investigated the electronic and chemical properties of model bimetallic surface structures, in particular subsurface and surface monolayers, using a combination of experimental and theoretical modeling to gain further insights into these factors. In the current presentation we will first utilize the adsorption and desorption of hydrogen to demonstrate the correlation between the hydrogen binding energy and the center of the surface d-band in various bimetallic surfaces. We will also provide a general equation that allows one to predict how the electronic properties, especially the d-band center, will be affected in bimetallic systems. We will then use several probe reactions, including hydrogenation of alkenes and reforming of oxygenates, to show the correlation between the chemical activities and the surface d-band center of bimetallic surfaces. Finally, we will discuss the relative stability of surface and subsurface bimetallic structures in vacuum, and in the presence of adsorbed hydrogen and oxygen.