An insight into alkali promotion: a density functional theory study of CO dissociation on K/Rh(111)

Zhi-Pan Liu, P Hu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

125 Citations (Scopus)

Abstract

The important role of alkali additives in heterogeneous catalysis is, to a large extent, related to the high promotion effect they have on many fundamental reactions. The wide application of alkali additives in industry does not, however, reflect a thorough understanding of the mechanism of their promotional abilities. To investigate the physical origin of the alkali promotion effect, we have studied CO dissociation on clean Rh(111) and K-covered Rh(111) surfaces using density functional theory. By varying the position of potassium atoms relative to a dissociating CO, we have mapped out the importance of different K effects on the CO dissociation reactions. The K-induced changes in the reaction pathways and reaction barriers have been determined; in particular, a large reduction of the CO dissociation barrier has been identified. A thorough analysis of this promotion effect allows us to rationalize both the electronic and the geometrical factors that govern alkali promotion effect: (i) The extent of barrier reductions depends strongly on how close K is to the dissociating CO. (ii) Direct K-O bonding that is in a very short range plays a crucial role in reducing the barrier. (iii) K can have a rather long-range effect on the TS structure, which could reduce slightly the barriers.

Original languageEnglish
Pages (from-to)12596-12604
Number of pages9
JournalJournal of the American Chemical Society
Volume123
Issue number50
DOIs
Publication statusPublished - Nov 2001

ASJC Scopus subject areas

  • Chemistry(all)

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