Monoxide carbon frequency shift as a tool for the characterization of TiO2 surfaces: Insights from first principles spectroscopy
The adsorption and vibrational frequency of CO on defective and undefective titanium dioxide surfaces is examined applying first-principles molecular dynamics simulations. In particular, the vibrational frequencies are obtained beyond the harmonic approximation, through the time correlation function...
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todo:paper_00219606_v138_n12_p_Lustemberg2023-10-03T14:24:27Z Monoxide carbon frequency shift as a tool for the characterization of TiO2 surfaces: Insights from first principles spectroscopy Lustemberg, P.G. Scherlis, D.A. Atomic trajectories Characteristic bands Degree of reduction First-principles molecular dynamics Harmonic approximation Time correlation functions Titanium dioxide surfaces Vacancy concentration Adsorption Molecular dynamics Oxide minerals Surfaces Vacancies Titanium dioxide carbon monoxide titanium titanium dioxide article chemistry infrared spectrophotometry molecular dynamics surface property Carbon Monoxide Molecular Dynamics Simulation Spectrophotometry, Infrared Surface Properties Titanium The adsorption and vibrational frequency of CO on defective and undefective titanium dioxide surfaces is examined applying first-principles molecular dynamics simulations. In particular, the vibrational frequencies are obtained beyond the harmonic approximation, through the time correlation functions of the atomic trajectories. In agreement with experiments, at low CO coverages we find an upshift in the vibration frequency with respect to the free CO molecule, of 45 and 35 cm-1 on the stoichiometric rutile (110) and anatase (101) faces, respectively. A band falling 8 cm-1 below the frequency corresponding to the perfect face is observed for the reduced rutile (110) surface in the low vacancy concentration limit, where the adsorption is favored on Ti4 sites. At a higher density of defects, adsorption on Ti 3 sites becomes more stable, accompanied by a downshift in the stretching band. In the case of anatase (101), we analyze the effect of subsurface oxygen vacancies, which have been shown to be predominant in this material. Interestingly, we find that the adsorption of CO on five coordinate Ti atoms placed over subsurface vacancies is favored with respect to other Ti 4 sites (7.25 against 6.95 kcal/mol), exhibiting a vibrational redshift of 20 cm-1. These results provide the basis to quantitatively assess the degree of reduction of rutile and anatase surfaces via IR spectroscopy, and at the same time allow for the assignment of characteristic bands in the CO spectra on TiO2 whose origin has remained ambiguous. © 2013 American Institute of Physics. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00219606_v138_n12_p_Lustemberg |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Atomic trajectories Characteristic bands Degree of reduction First-principles molecular dynamics Harmonic approximation Time correlation functions Titanium dioxide surfaces Vacancy concentration Adsorption Molecular dynamics Oxide minerals Surfaces Vacancies Titanium dioxide carbon monoxide titanium titanium dioxide article chemistry infrared spectrophotometry molecular dynamics surface property Carbon Monoxide Molecular Dynamics Simulation Spectrophotometry, Infrared Surface Properties Titanium |
| spellingShingle |
Atomic trajectories Characteristic bands Degree of reduction First-principles molecular dynamics Harmonic approximation Time correlation functions Titanium dioxide surfaces Vacancy concentration Adsorption Molecular dynamics Oxide minerals Surfaces Vacancies Titanium dioxide carbon monoxide titanium titanium dioxide article chemistry infrared spectrophotometry molecular dynamics surface property Carbon Monoxide Molecular Dynamics Simulation Spectrophotometry, Infrared Surface Properties Titanium Lustemberg, P.G. Scherlis, D.A. Monoxide carbon frequency shift as a tool for the characterization of TiO2 surfaces: Insights from first principles spectroscopy |
| topic_facet |
Atomic trajectories Characteristic bands Degree of reduction First-principles molecular dynamics Harmonic approximation Time correlation functions Titanium dioxide surfaces Vacancy concentration Adsorption Molecular dynamics Oxide minerals Surfaces Vacancies Titanium dioxide carbon monoxide titanium titanium dioxide article chemistry infrared spectrophotometry molecular dynamics surface property Carbon Monoxide Molecular Dynamics Simulation Spectrophotometry, Infrared Surface Properties Titanium |
| description |
The adsorption and vibrational frequency of CO on defective and undefective titanium dioxide surfaces is examined applying first-principles molecular dynamics simulations. In particular, the vibrational frequencies are obtained beyond the harmonic approximation, through the time correlation functions of the atomic trajectories. In agreement with experiments, at low CO coverages we find an upshift in the vibration frequency with respect to the free CO molecule, of 45 and 35 cm-1 on the stoichiometric rutile (110) and anatase (101) faces, respectively. A band falling 8 cm-1 below the frequency corresponding to the perfect face is observed for the reduced rutile (110) surface in the low vacancy concentration limit, where the adsorption is favored on Ti4 sites. At a higher density of defects, adsorption on Ti 3 sites becomes more stable, accompanied by a downshift in the stretching band. In the case of anatase (101), we analyze the effect of subsurface oxygen vacancies, which have been shown to be predominant in this material. Interestingly, we find that the adsorption of CO on five coordinate Ti atoms placed over subsurface vacancies is favored with respect to other Ti 4 sites (7.25 against 6.95 kcal/mol), exhibiting a vibrational redshift of 20 cm-1. These results provide the basis to quantitatively assess the degree of reduction of rutile and anatase surfaces via IR spectroscopy, and at the same time allow for the assignment of characteristic bands in the CO spectra on TiO2 whose origin has remained ambiguous. © 2013 American Institute of Physics. |
| format |
JOUR |
| author |
Lustemberg, P.G. Scherlis, D.A. |
| author_facet |
Lustemberg, P.G. Scherlis, D.A. |
| author_sort |
Lustemberg, P.G. |
| title |
Monoxide carbon frequency shift as a tool for the characterization of TiO2 surfaces: Insights from first principles spectroscopy |
| title_short |
Monoxide carbon frequency shift as a tool for the characterization of TiO2 surfaces: Insights from first principles spectroscopy |
| title_full |
Monoxide carbon frequency shift as a tool for the characterization of TiO2 surfaces: Insights from first principles spectroscopy |
| title_fullStr |
Monoxide carbon frequency shift as a tool for the characterization of TiO2 surfaces: Insights from first principles spectroscopy |
| title_full_unstemmed |
Monoxide carbon frequency shift as a tool for the characterization of TiO2 surfaces: Insights from first principles spectroscopy |
| title_sort |
monoxide carbon frequency shift as a tool for the characterization of tio2 surfaces: insights from first principles spectroscopy |
| url |
http://hdl.handle.net/20.500.12110/paper_00219606_v138_n12_p_Lustemberg |
| work_keys_str_mv |
AT lustembergpg monoxidecarbonfrequencyshiftasatoolforthecharacterizationoftio2surfacesinsightsfromfirstprinciplesspectroscopy AT scherlisda monoxidecarbonfrequencyshiftasatoolforthecharacterizationoftio2surfacesinsightsfromfirstprinciplesspectroscopy |
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