Structure and Dynamics of CO₂ on Rutile TiO₂ (110)-1×1

Journal Article · Tue Oct 30 00:00:00 EDT 2012 · Journal of Physical Chemistry. C

DOI:https://doi.org/10.1021/jp308061j· OSTI ID:1059191

Lin, Xiao ^[1]; Yoon, Yeohoon ^[1]; Petrik, Nikolay G. ^[1]; Li, Zhenjun ^[1]; Wang, Zhi-Tao ^[1]; Glezakou, Vassiliki-Alexandra ^[1]; Kay, Bruce D. ^[1]; Lyubinetsky, Igor ^[1]; Kimmel, Greg A. ^[1]; Rousseau, Roger ^[1]; Dohnálek, Zdenek ^[1]

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1. Fundamental and Computational Sciences Directorate, §Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States

Adsorption, binding, and diffusion of CO2 molecules on rutile TiO2(110) model surfaces was investigated experimentally using scanning tunneling microscopy, infrared reflection adsorption spectroscopy (IRAS), temperature programmed desorption and theoretically via dispersion corrected density functional theory and ab initio molecular dynamics. In accord with previous studies, bridging oxygen (Ob) vacancies (VO’s) are found to be the most stable binding sites. Additional CO2 adsorbs on 5-coordinated Ti sites (Ti5c) with the initial small fraction is stabilized by CO2 on VO sites. The Ti5c-bound CO2 is found to be highly mobile at 50 K at coverages of up to 1/2 monolayer (ML). Theoretical studies show that the CO2 diffusion on Ti5c rows proceeds via a rotation-tumbling mechanism with extremely low barrier of 0.06 eV. The Ti5c-bound CO2 molecules are found to bind preferentially to a single Ti5c with the O=C=O axis tilted away from the surface normal. The binding energy of tilted CO2 molecules changes only slightly with changes in the azimuth of the CO2 tilt angle. At 2/3 ML, CO2 diffusion is hindered and at 1 ML an ordered (2×2) overlayer with a zigzag arrangement of tilted CO2 molecules develops along the Ti5c rows. Out of phase arrangement of the zigzag chains is observed across the rows. An additional 0.5 ML of CO2 can be adsorbed at Ob sites with a binding energy only slightly lower than that on Ti5c sites due to quadrupole-quadrupole interactions with the Ti5c-bound CO2 molecules.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1059191
• Report Number(s): PNNL-SA-89052; 46005; 40077; 39940; KC0302010
• Journal Information: Journal of Physical Chemistry. C, Vol. 116, Issue 50; ISSN 1932-7447
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

Environmental Molecular Sciences Laboratory