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Chemphyschem. 2016 Jul 4;17(13):1956-60. doi: 10.1002/cphc.201600284. Epub 2016 Apr 23.

On the Simple Complexity of Carbon Monoxide on Oxide Surfaces: Facet-Specific Donation and Backdonation Effects Revealed on TiO2 Anatase Nanoparticles.

Author information

1
Department of Chemistry and NIS Centre, University of Turin, Via P. Giuria 7, 10125, Torino, Italy.
2
Department of Science and High Technology, University of Insubria and INSTM, Via Valleggio 9, 22100, Como, Italy.
3
Department of Chemistry and NIS Centre, University of Turin, Via P. Giuria 7, 10125, Torino, Italy. gianmario.martra@unito.it.
4
Solaronix SA, Rue de l'Ouriette 129, 1170, Aubonne, Switzerland.
5
Department of Science and High Technology, University of Insubria and INSTM, Via Valleggio 9, 22100, Como, Italy. gloria.tabacchi@uninsubria.it.

Abstract

Atomic-scale relationships between the structure of TiO2 surfaces and the physicochemical properties of surface sites, functional for titania-based applications, can be obtained from IR spectroscopy by using carbon monoxide (CO) as a molecular probe. In the literature, it is reported that strongly unsaturated cationic Ti sites (Lewis acid), which are important for reactivity, should cause a large upshift of the CO stretching frequency. By using IR spectroscopy of CO on TiO2 nanomaterials and theoretical analyses, here this model is challenged. It is shown that the stretching frequency of adsorbed CO results from a facet-dependent and synergic CO-surface donation (upshift) - surface-CO backdonation (downshift) mechanism. These results imply that the interaction of adsorbed molecules with the Ti centers is tuned by the surface oxygen atoms of the first coordination sphere, which play an active role as indirect electron density donors (Lewis base).

KEYWORDS:

IR spectroscopy; density functional calculations; metal oxide nanoparticles; molecule-surface interactions; titanium dioxide

PMID:
27003518
DOI:
10.1002/cphc.201600284

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