Accessibility navigation

Phase mixing and phase separation accompanying the catalytic oxidation of CO on Ir{100}

Lerotholi, T.J., Held, G. and King, D.A. (2007) Phase mixing and phase separation accompanying the catalytic oxidation of CO on Ir{100}. Surface Science, 601 (5). pp. 1285-1295. ISSN 0039-6028

Full text not archived in this repository.

It is advisable to refer to the publisher's version if you intend to cite from this work. See Guidance on citing.

To link to this item DOI: 10.1016/j.susc.2006.12.067


The co-adsorption of CO and O on the unreconstructed (1 x 1) phase of Ir {100} was examined by low energy electron diffraction (LEED) and temperature programmed desorption (TPD). When CO is adsorbed at 188 K onto the Ir{100} surface precovered with 0.5 ML O, a mixed c(4 x 2)-(2O + CO) overlayer is formed. All CO is oxidised upon heating and desorbs as CO2 in three distinct stages at 230 K, 330 K and 430 K in a 2:1:2 ratio. The excess oxygen left on the surface after all CO has reacted forms an overlayer with a LEED pattern with p(2 x 10) periodicity. This overlayer consists of stripes with a local p(2 x 1)-O arrangement of oxygen atoms separated by stripes of uncovered It. When CO is adsorbed at 300 K onto the surface precovered with 0.5 ML O an apparent (2 x 2) LEED pattern is observed. LEED IV analysis reveals that this pattern is a superposition of diffraction patterns from islands of c(2 x 2)-CO and p(2 x 1)-O structures on the surface. Heating this co-adsorbed overlayer leads to the desorption of CO, in two stages at 330 K and 430 K; the excess CO (0.1 ML) desorbs at 590 K. LEED IV structural analysis of the mixed c(4 x 2) O and CO overlayer shows that both the CO molecules and the O atoms occupy bridge sites. The O atoms show significant lateral displacements of 0.14 angstrom away from the CO molecules; the C-O bond is slightly expanded with respect to the gas phase (1.19 angstrom); the modifications of the Ir substrate with respect to the bulk-terminated surface are very small. (c) 2006 Elsevier B.V. All rights reserved.

Item Type:Article
Divisions:Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
ID Code:11421
Uncontrolled Keywords:low energy electron diffraction (LEED), thermal desorption spectroscopy, chemisorption, catalysis, iridium, carbon monoxide, oxygen , LEED-IV DETERMINATION, CARBON-MONOXIDE, OXYGEN, SURFACE, COADSORPTION, ADSORPTION, GEOMETRY, RH(111), RH(100), KINETICS

University Staff: Request a correction | Centaur Editors: Update this record

Page navigation