The University of Southampton
University of Southampton Institutional Repository

A comparison of the chemistry of Rh-I(acac)(CO)(2) and Rh-I(CO)(2)Cl adsorbed on TiO2 110 : development of particulate Rh and oxidative disruption by CO

Evans, J., Hayden, B. E. and Newton, M. A. (2000) A comparison of the chemistry of Rh-I(acac)(CO)(2) and Rh-I(CO)(2)Cl adsorbed on TiO2 110 : development of particulate Rh and oxidative disruption by CO Surface Science, 462, (1-3), pp. 169-180. (doi:10.1016/S0039-6028(00)00604-X).

Record type: Article


Boom-temperature metallo-organic chemical vapour deposition (MOCVD) of Rh(acac)(2)(CO)(2) [(acac) = (CH3CO)(2)CH] to the TiO2{110} surface leads to the formation of a molecular adlayer. Thermal desorption (TPD) and XPS indicate that the geminal dicarbonyl species derived from the Rh(acac)(CO)(2) species is the most thermally labile component of the adsorbed layer and is comparable in stability to that derived from [Rh(CO)(2)Cl](2) adsorption. The (acac) ligand undergoes a complex decomposition in the temperature region 500-775 K, and the carbon left behind appears to perturb the subsequent clustering Rh. The Rh 3d(5/2) binding energy (BE) is approximately constant at similar to 307.4-307.2 eV in this temperature region, whereas in the [Rh(CO)(2)Cl](2)-derived system, a BE of similar to 307 eV (corresponding to Rh-0) is attained by 600 K. A Rh 3d(5/2) BE of 307 eV is only attained at T > 775 K, and the remaining C residues are reacted away as CO by substrate oxygen. Ti 2p difference spectra show the formation of two distinct features during thermal treatment. One appears at high temperature with a BE shifted by similar to -2.0 eV from the bulk Ti4+ photoelectron line and is associated with substrate reduction to Ti3+ and the oxidation of surface bound carbon residues. The second appears at similar to -1.5 eV from the Ti4+ line. This feature appears in concert with the decomposition of the Rh organometallics and is shown to be precursor-dependent both in magnitude and the temperature range in which it persists. Exposure of the thermally decomposed (600 K, Rh 3d(5/2) BE similar to 307.3 eV) Rh(acac)(CO)(2)/TiO2 {110} to CO provides evidence for two stages in Rh redispersion. At room temperature, a species (C Is BE similar to 286.6 eV: Rh 3d(5/2) BE similar to 307.5) indicative of CO adsorption upon small Rh particles is observed. Further exposure to CO at a slightly elevated temperature leads to both linear CO species (BE 286 eV) and regeneration of around 25% of a geminal dicarbonyl species (BE 287.7 eV); this occurs in the absence of Cl and despite a surface C/Rh stoichiometry of similar to 2-3. The latter observation indicates a mixture of CO-induced Rh redispersion and agglomeration. (C) 2000 Elsevier Science B.V. All rights reserved.

Full text not available from this repository.

More information

Published date: 10 August 2000
Keywords: carbon monoxide, chemical vapor deposition, rhodium, surface chemical reaction, thermal desorption spectroscopy, titanium oxide, x-rayphotoelectron spectroscopycarbon-monoxide hydrogenation, metal-support interactions, inducedstructural-changes, absorption fine-structure, rhodium gem-dicarbonyl, electron-microscopy, tio2(110), catalysts, surface, dissociation


Local EPrints ID: 19054
ISSN: 0039-6028
PURE UUID: 072378da-c5ec-41b9-b823-dfdcfe82e456

Catalogue record

Date deposited: 18 Jan 2006
Last modified: 17 Jul 2017 16:34

Export record



Author: J. Evans
Author: B. E. Hayden
Author: M. A. Newton

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton:

ePrints Soton supports OAI 2.0 with a base URL of

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.