Tailoring the reactivity of bimetallic overlayer and surface alloy systems.

Changing the composition and structure of a bimetallic surface system modifies its electronic properties and thus its catalytic activity. On the basis of density functional theory calculations, the electronic factors underlying the modified properties of bimetallic surfaces such as overlayer systems and, in particular, surface alloys will be discussed. It will be demonstrated that by mixing two metals a new metallic compound can result whose properties are not intermediate but beyond those of both constituents, so that for example by adding a relatively inert metal a more reactive surface can result. Besides the reactivity, the stability of the bimetallic systems will also be briefly discussed.