Growth of a Pt film on non-reduced ceria: a density functional theory study.
The growth of platinum on non-reduced CeO(2) (111) surface is studied by means of calculations based on the density functional theory. Particles of increasing size are formed on the oxide surface by incorporating the platinum atoms one by one until multilayer films are obtained. The main conclusion is that platinum atoms tend to maximize the number of metallic bonds and to approach the situation of the bulk, hence preferring films to particles, particles to isolated atoms, and a three-dimensional growth to a two-dimensional one. The supported particles and the films exhibit a contraction of the Pt-Pt distances, with respect to those of the Pt bulk, in order to match the ceria lattice. The density of states projected on the film surface platinum atoms shows important differences in shape and energy (lower d-band center) compared to the Pt(111) reference surface, which could be the major reason for the observed changes in catalytic reactivity when deposited particles are compared with single crystal surfaces.
Université de Lyon, Institut de Chimie, Laboratoire de Chimie, Ecole Normale Supérieure de Lyon and CNRS, 46 Allée d'Italie, F-69364 Lyon Cedex 07, France.
David
D
Loffreda
Françoise
F
Delbecq