Abstract
The adsorption of CO at regular and defect sites of the TiC surface has been studied by means of density functional theory (DFT) based calculations and temperature programmed desorption experiments (TPD) using TiC nanopowders as substrate whose structure and morphology have been characterized by X-ray diffraction and both scanning and transmission electron microscopy. The results obtained confirm previous work indicating that the nature of CO adsorption is strongly dependent on surface coverage due to the distortion of the surface induced by the adsorbate and also allows one to resolve an apparent anomaly between theory and experiment. Calculations and TPD experiments show that CO adsorption strength at regular sites is rather large with an adsorption energy of about - 1.60 eV which is consistent with a main desorption peak at ~ 500 K. Adsorption at low coordinated sites is even stronger and in agreement with desorption experiments indicating that CO continues to desorb at temperatures as high as 600 K.
Original language | English |
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Pages (from-to) | 63-73 |
Number of pages | 11 |
Journal | Surface Science |
Volume | 613 |
Early online date | 16 Mar 2013 |
DOIs | |
Publication status | Published - Jul 2013 |
Bibliographical note
The authors are indebted to Prof. Piefranco Demontis, Dr. Federico G. Pazzona and M.Sc. Andrea Gabrieli of the Università degli Studi di Sassari for the fruitful discussions on the kinetic Monte Carlo methods. BM thanks the Erasmus programme for financing his stay at the Universitat de Barcelona, GGA thanks Universitat Rovira i Virgili for supporting his pre-doctoral research and FI acknowledges support received through the “2009 ICREA Academia” prize for excellence in research. Financial support has been provided by the Spanish MICINN/MINECO (grants FIS2008-02238, CTQ2008-06549-C02-01, Consolider Ingenio2010, Multicat CSD2009-00050 and MAT2011-23775) and in part by Generalitat de Catalunya (grants 2009SGR1041, 2009SGR00462, 2009SGR-0674 and XRQTC). Calculations were carried out, in part, at the CESCA and BCS supercomputer centres.Keywords
- CO
- DFT
- Low coordinated sites
- TiC