Abstract
Combined scanning tunneling microscopy (STM), X-rays photoelectron spectroscopy (XPS) and density functional theory (DFT) studies have probed the bonding configurations and mobility of trimethylacetic acid (TMAA) molecules on the TiO2(110) surface at RT. Upon TMAA dissociation through deprotonation, two distinctly different types of stable chemisorption configurations of the carboxylate group (TMA) have been identified according to their position and appearance in STM images. In configuration A, two carboxylate O atoms bond to two Ti4+ cations, while in configuration B one O atom fills the bridging oxygen vacancy (VO) with the other O bounded at an adjacent regular Ti4+ site. Calculated adsorption energies for the configurations A and B are comparable at 1.28 and 1.36 eV, respectively. DFT results also show that TMA may rotate at RT about its O atom that filled the VO (in configuration B), with a rotation barrier of ∼0.65 eV. Both the observation of the constant initial sticking coefficient and preference for TMAA molecules to dissociate at selective sites indicate that TMAA adsorption is mediated by a mobile precursor state. Several possible molecular (physisorbed) states of TMAA have indeed been identified by DFT, all being highly mobile at RT. In contrast, the TMA diffusion in the chemisorbed (dissociative) state is a very slow with a calculated barrier of 1.09 eV for diffusion along the Ti row.
| Original language | English |
|---|---|
| Pages (from-to) | 5986-5992 |
| Number of pages | 7 |
| Journal | Physical Chemistry Chemical Physics |
| Volume | 12 |
| Issue number | 23 |
| DOIs | |
| Publication status | Published - Jun 21 2010 |
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ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Physics and Astronomy(all)
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Adsorption states and mobility of trimethylacetic acid molecules on reduced TiO2(110) surface. / Lyubinetsky, Igor; Deskins, N. Aaron; Du, Yingge; Vestergaard, Ebbe K.; Kim, Dong Jun; Dupuis, Michel.
In: Physical Chemistry Chemical Physics, Vol. 12, No. 23, 21.06.2010, p. 5986-5992.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Adsorption states and mobility of trimethylacetic acid molecules on reduced TiO2(110) surface
AU - Lyubinetsky, Igor
AU - Deskins, N. Aaron
AU - Du, Yingge
AU - Vestergaard, Ebbe K.
AU - Kim, Dong Jun
AU - Dupuis, Michel
PY - 2010/6/21
Y1 - 2010/6/21
N2 - Combined scanning tunneling microscopy (STM), X-rays photoelectron spectroscopy (XPS) and density functional theory (DFT) studies have probed the bonding configurations and mobility of trimethylacetic acid (TMAA) molecules on the TiO2(110) surface at RT. Upon TMAA dissociation through deprotonation, two distinctly different types of stable chemisorption configurations of the carboxylate group (TMA) have been identified according to their position and appearance in STM images. In configuration A, two carboxylate O atoms bond to two Ti4+ cations, while in configuration B one O atom fills the bridging oxygen vacancy (VO) with the other O bounded at an adjacent regular Ti4+ site. Calculated adsorption energies for the configurations A and B are comparable at 1.28 and 1.36 eV, respectively. DFT results also show that TMA may rotate at RT about its O atom that filled the VO (in configuration B), with a rotation barrier of ∼0.65 eV. Both the observation of the constant initial sticking coefficient and preference for TMAA molecules to dissociate at selective sites indicate that TMAA adsorption is mediated by a mobile precursor state. Several possible molecular (physisorbed) states of TMAA have indeed been identified by DFT, all being highly mobile at RT. In contrast, the TMA diffusion in the chemisorbed (dissociative) state is a very slow with a calculated barrier of 1.09 eV for diffusion along the Ti row.
AB - Combined scanning tunneling microscopy (STM), X-rays photoelectron spectroscopy (XPS) and density functional theory (DFT) studies have probed the bonding configurations and mobility of trimethylacetic acid (TMAA) molecules on the TiO2(110) surface at RT. Upon TMAA dissociation through deprotonation, two distinctly different types of stable chemisorption configurations of the carboxylate group (TMA) have been identified according to their position and appearance in STM images. In configuration A, two carboxylate O atoms bond to two Ti4+ cations, while in configuration B one O atom fills the bridging oxygen vacancy (VO) with the other O bounded at an adjacent regular Ti4+ site. Calculated adsorption energies for the configurations A and B are comparable at 1.28 and 1.36 eV, respectively. DFT results also show that TMA may rotate at RT about its O atom that filled the VO (in configuration B), with a rotation barrier of ∼0.65 eV. Both the observation of the constant initial sticking coefficient and preference for TMAA molecules to dissociate at selective sites indicate that TMAA adsorption is mediated by a mobile precursor state. Several possible molecular (physisorbed) states of TMAA have indeed been identified by DFT, all being highly mobile at RT. In contrast, the TMA diffusion in the chemisorbed (dissociative) state is a very slow with a calculated barrier of 1.09 eV for diffusion along the Ti row.
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U2 - 10.1039/b921921h
DO - 10.1039/b921921h
M3 - Article
C2 - 20490397
AN - SCOPUS:77955966183
VL - 12
SP - 5986
EP - 5992
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
SN - 1463-9076
IS - 23
ER -