Abstract
The adsorption and dissociation of carbon monoxide were studied with plane-wave density functional theory on flat Rh(111), stepped and kinked Rh(553), and Ni-decorated Rh(553) surfaces. The theoretical results were compared to high-resolution X-ray photoelectron spectroscopy (HR-XPS) experiments. The most favorable CO adsorption sites for low coverages were identified by a systematic calculation of the adsorption energies, and their sequence of occupation as a function of CO exposure was determined experimentally in C 1s HR-XPS spectra via their characteristic surface core-level shifts. On the clean, stepped (553) surface, molecular CO is adsorbed more strongly on low-coordinated top sites at the step edge, but on the Ni-decorated surface, the binding is stronger at the terrace sites. The barrier for dissociation with respect to the gas phase is about 1 eV lower on the stepped Rh(553) surface than on the flat Rh(111) surface, implying a substantially higher reaction rate. The presence of kinks at the clean Rh(553) surface does not lead to a significant additional decrease of the dissociation barriers, resulting in dissociation energies just above the desorption threshold for both stepped and kinked surfaces, whereas the barrier can be additionally lowered by about 0.1 eV by decorating the step edges with Ni stripes. Whereas no dissociation of CO was observed by HR-XPS on the clean Rh(553) surface, a minor amount of CO dissociation was found on the Ni-decorated Rh surface, in agreement with the theoretical predictions.
Original language | English |
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Pages (from-to) | 942-949 |
Number of pages | 8 |
Journal | The Journal of Physical Chemistry Part C (Nanomaterials and Interfaces) |
Volume | 113 |
Issue number | 3 |
DOIs | |
Publication status | Published - 2009 |
Austrian Fields of Science 2012
- 103018 Materials physics