Promoters, poisons and surfactants: electronic effects of surface doping on metals
The interaction of adsorbates with metal surfaces is discussed. It is shown that the evanescent charge density produced by occupied sp derived surface states yields a considerable contribution to the Pauli repulsion experienced by adsorbate particles with a closed-shell electronic structure, eg rare-gases or molecules such as H(2) or N(2). For rare-gases this results in a reduction of the binding energy in the presence of occupied surface states, for molecules this gives rise to an additional contribution to the dissociation barrier. Suitable surface dopants are able to depopulate surface states and thereby to reduce the dissociation barrier. Such dopants can substantially promote catalytic reactions in which the dissociation from the gas phase or a physisorbed precursor is the rate limiting step.
Bibliographic Reference: Article: Applied Physics A, Vol. 63 (1996) pp. 523-531
Record Number: 199710552 / Last updated on: 1997-05-09
Original language: en
Available languages: en