Infrared study of the surface of titanium dioxides. I. Hydroxyl groups

Primet, Michel; Pichat, Pierre; Mathieu, Michel-Vital

doi:10.1021/j100679a007

Cited by 573 publications

(347 citation statements)

References 4 publications

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“…The infrared spectrum of TiO 2 obtained after the pre-treatment displays bands around 3000 cm -1 which are ascribed to residual surface OH groups [6][7]. According to a previous study, the pre-treated [2].…”

Section: Methodsmentioning

confidence: 82%

IR spectroscopy of CH₂CBrF adsorbed on TiO₂ and quantum-mechanical studies

et al. 2009

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International audienceThe adsorption at room temperature of 1-bromo-1-fluoroethene (CH2CBrF) on TiO2 has been investigated by Fourier-transform infrared spectroscopy after a preventive assignment of the fundamentals in the gas-phase, carried out for the first time. The spectrum resulting from the adsorption has been compared with the gas-phase one and the most important differences consist in a red-shift of the CH2 stretching vibration and in the presence of two distinct absorptions for both the C=C and C-F stretching modes. Basing on the observed features it has been inferred that there is the formation of an H-bond between the CH2 group and a surface Lewis basic site and that the adsorption can occur through the double C=C bond or the F atom. Two proposed adsorbate-substrate structures have been investigated by periodic quantum-mechanical calculations at DFT/B3LYP level considering the rutile (110) surface. In the case of the adsorption by the F atom, also the formation of the H-bond has been considered. The interaction energy resulting from the adsorption through the double C=C bond is smaller than that arising from the interaction by means the F atom and the H-bond. The shifts due to the adsorption of the calculated vibrational frequencies well reproduce the experimental data

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Section: Methodsmentioning

confidence: 82%

IR spectroscopy of CH₂CBrF adsorbed on TiO₂ and quantum-mechanical studies

et al. 2009

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“…44,48 In principle, two mechanisms can be proposed: an O 2 dissociation taking place without help from the CO molecule; or, more commonly, an assisted mechanism where the CO molecule helps in the O 2 dissociation (Fig. 5).…”

Section: Resultsmentioning

confidence: 99%

Surface oxygen vacancies in gold based catalysts for CO oxidation

et al. 2014

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Experimental catalytic activity measurements, diffuse reflectance infrared Fourier spectroscopy, and density functional theory calculations are used to investigate the role and dynamics of surface oxygen vacancies in CO oxidation with O 2 catalyzed by Au nanoparticles supported on a Y-doped TiO 2 catalyst. Catalytic activity measurements show that the CO conversion is improved in a second cycle of reaction if the reactive flow is composed by CO and O 2 (and inert) while if water is present in the flow, the catalyst shows a similar behaviour in two successive cycles. DRIFTS-MS studies indicate the occurrence of two simultaneous phenomena during the first cycle in dry conditions: the surface is dehydroxylated and a band at 2194 cm À1 increases (proportionally to the number of surface oxygen vacancies). Theoretical calculations were conducted in order to explain these observations. On one hand, the calculations show that there is a competition between gold nanoparticles and OH to occupy the surface oxygen vacancies and that the adsorption energy of gold on these sites increases as the surface is being dehydroxylated. On the other hand, these results evidence that a strong electronic transfer from the surface to the O 2 molecule is produced after its adsorption on the Au/TiO 2 perimeter interface (activation step), leaving the gold particle in a high oxidation state. This explains the appearance of a band at a wavenumber unusually high for the CO adsorbed on oxidized gold particles (2194 cm À1 ) when O 2 is present in the reactive flow.These simultaneous phenomena indicate that a gold redispersion on the surface occurs under reactive flow in dry conditions generating small gold particles which are very active at low temperature. This fact is notably favoured by the presence of surface oxygen vacancies that improve the surface dynamics. The obtained results suggest that the reaction mechanism proceeds through the formation of a peroxo-like complex formed after the electronic transfer from the surface to the gas molecule.

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“…1,39,40 The difference between them is whether OH interacts with adjacent OH groups via hydrogen bonding. According to previous infrared studies, the absorption frequencies of isolated OH groups on TiO 2 surfaces are always higher than those of H-bonded OH groups.…”

Section: Types Of Surface Oh Groups On Tiomentioning

confidence: 99%

Structure–activity relationship of surface hydroxyl groups during NO₂ adsorption and transformation on TiO₂ nanoparticles

Liu

et al. 2017

Environ. Sci.: Nano

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The role of hydroxyl groups (OH) is significant in understanding the surface reactions on oxides. Here we combined spectroscopic experiments and theoretical calculations to reveal the role of OH in the heterogeneous reactions of NO 2 on TiO 2 nanoparticles with various crystal structures. The interaction between OH and NO 2 was determined to be a critical step, giving rise to the formation of surface HNO 3 . HNO 3 was found to be either a stable product on amorphous TiO 2 , or an important intermediate of nitrate on anatase due to its further reaction with nearby OH. The lack of surface OH on rutile limited its reactivity toward NO 2 . This study presents clear evidence that the reactivity of TiO 2 toward NO 2 greatly depends on the surface OH as well as the crystalline form. Considering the ubiquitous presence of TiO 2 nanoparticles in catalysts and in natural environments, our results could provide insights helpful to future research in both environmental catalysis and atmospheric chemistry.

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Infrared study of the surface of titanium dioxides. I. Hydroxyl groups

Cited by 573 publications

References 4 publications

IR spectroscopy of CH₂CBrF adsorbed on TiO₂ and quantum-mechanical studies

IR spectroscopy of CH₂CBrF adsorbed on TiO₂ and quantum-mechanical studies

Surface oxygen vacancies in gold based catalysts for CO oxidation

Structure–activity relationship of surface hydroxyl groups during NO₂ adsorption and transformation on TiO₂ nanoparticles

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Infrared study of the surface of titanium dioxides. I. Hydroxyl groups

Cited by 573 publications

References 4 publications

IR spectroscopy of CH2CBrF adsorbed on TiO2 and quantum-mechanical studies

IR spectroscopy of CH2CBrF adsorbed on TiO2 and quantum-mechanical studies

Surface oxygen vacancies in gold based catalysts for CO oxidation

Structure–activity relationship of surface hydroxyl groups during NO2 adsorption and transformation on TiO2 nanoparticles

Contact Info

Product

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IR spectroscopy of CH₂CBrF adsorbed on TiO₂ and quantum-mechanical studies

IR spectroscopy of CH₂CBrF adsorbed on TiO₂ and quantum-mechanical studies

Structure–activity relationship of surface hydroxyl groups during NO₂ adsorption and transformation on TiO₂ nanoparticles