Tailoring the Surface Reactivity: Comparison of Pd/Nb(110) and Rh/Nb(110)

Abstract

Ni, Pd and Pt overlayers deposited on many metallic surfaces show properties resembling those of noble metals. We pose the question whether a similar trend might occur also for other transition-metal overlayers. To this goal, we perform first-principles density-functional theory calculations for Pd(111), Rh(111) surfaces, Pd and Rh epitaxial monolayers deposited on Nb(110), and for CO chemisorption on these systems. Density functional calculations indicate that the behavior of the two overlayers is quite different. Whereas the Rh overlayer on Nb(110) resembles the Rh(111) surface, for the Pd overlayer the electronic structure around the Fermi level is strongly affected by hybridization with Nb electrons, which accounts for unique properties of the overlayer. We expect that the latter mechanism may be of importance just for Pd, Pt, Ni and not for other transition metals with lower d-electron occupation.