Hydrogen adsorption on Pd-containing Au(111) bimetallic surfaces.

Configurations of different Pd-containing Au(111) bimetallic surfaces with Pd substituents varying from one to three atoms have been studied using density functional theory. The stability of the so-formed Pd monomers, dimers or trimers in the surface and subsurface layers of a Au(111)-(3 x 3) unit cell and their influence on the adsorption of hydrogen have been investigated. We find that before hydrogen adsorption the surface prefers to form Pd monomers over dimers or trimers located in subsurface positions, which is in agreement with experimental observations.