Tracking hydroxyl adsorption on TiO2 (110) through secondary emission changes

Canário, A.R.; Moutinho, A.M.C.; Teodoro, O.M.N.D.

doi:10.1016/j.apsusc.2009.04.006

Cited by 17 publications

(8 citation statements)

References 21 publications

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“…Photobiol. Sci., 2012, 11, 687-691 | 689 function on the order of ∼0.4 eV for water absorption on TiO 2 surface, 15 in excellent agreement with that revealed by this analysis. Therefore we conclude that the change in photoemission intensity of the substrate reflects desorption of water.…”

Section: Resultssupporting

confidence: 86%

“…The work function of TiO 2 is sensitive to surface conditions. 15,16 Absorption of water to the surface of TiO 2 occurs dissociatively at oxygen vacancies, leaving two OH groups on the surface. Marques et al and Rocker report that surface hydroxylation of TiO 2 results in a decrease of the surface work function.…”

Section: Resultsmentioning

confidence: 99%

“…A crystal that had undergone many cycles of sputtering and annealing, which presented a higher defect concentration, exhibited a larger change, on the order of 1.2 eV. 15 The crystals used in the PEEM experiments described herein were new substrates.…”

Section: Resultsmentioning

confidence: 99%

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The effect of hydration on the UV absorption coefficient of intact melanosomes

Lin

Peles

Simon

2012

Photochem Photobiol Sci

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The physical properties of melanosomes have been shown to depend on water content. Herein, the ultraviolet absorption coefficient at λ = 244 nm for intact bovine choroidal melanosomes is determined from photoemission electron microscopy images recorded as a function of vacuum exposure. The dehydration of the melanosome under ultra-high vacuum manifests itself by a decrease in the absorption coefficient to about 60% of its initial value, and a concomitant increase in its image brightness. This change in the absorption of the melanosome is consistent with the influence of solvent polarity on the UV absorption coefficient of model systems for the pigment eumelanin, the predominant UV absorber contained in the choroid melanosomes.

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Section: Resultssupporting

confidence: 86%

Section: Resultsmentioning

confidence: 99%

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The effect of hydration on the UV absorption coefficient of intact melanosomes

Lin

Peles

Simon

2012

Photochem Photobiol Sci

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“…Different regimes of water adsorption (molecular versus dissociative) were observed on different facets of titania, − indicating complex structure–properties relationships. The dissociative adsorption, important for water splitting in photocatalytic applications, leads to protonation/hydroxylation of TiO 2 surfaces, which was observed in various experiments such as STM, potentiometry, or spectrometry. − The adsorption depends naturally on temperature and coverage of the surface, which affect the arrangement and stability of interfacial hydrogen-bond network. − …”

Section: Introductionmentioning

confidence: 99%

Exploring Rutile (110) and Anatase (101) TiO₂ Water Interfaces by Reactive Force-Field Simulations

Futera

English

2017

J. Phys. Chem. C

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We have investigated static/structural as well as dynamical properties of anatase (101) and rutile (110) TiO2 interfaces with liquid bulk water by reactive force fields (ReaxFF). Layered, well-organized structure of water in the interface region was clearly observed within 6.5 Å of the surfaces. The first-hydration layer molecules adsorbed to unsaturated surface Ti atoms undergo spontaneous dissociation leading, rather controversially, to full coverage of O2c/Ob by H+ and partial coverage of Ti5c by OH–. Expected large variations of intrinsic electric field on the interfaces, and drop of electrostatic potential, were detected. Interfacial water was found to be heavily confined with a self-diffusion constant of 2 orders of magnitude lower than 2.28 × 10–9 m2/s measured in the bulk water region. Moreover, the rotational movement of adsorbed water molecules was found to be considerably hindered as well. On the other hand, the calculated hydrogen-bond lifetime on the interface was shorter than in bulk water for both surface types. Finally, the IR spectra obtained from collective-water-dipole variations in the interfacial region revealed stronger effects on stretching vibrations on anatase (101) than on rutile (110); however, description of liquid-water bond-stretching vibrations generally suffers from lack of accuracy in the applied reactive potential.

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“…Besides classical MD based on empirical potentials, density functional theory (DFT) proved to be very useful for investigating electro-chemical changes occurring on the TiO 2 surfaces. 30 Protonation and hydroxylation of titania in contact with water observed experimentally by STM, [31][32][33][34] potentiometric, 35 and spectroscopic measurements 36 were studied by many DFT studies which revealed important role of oxygen vacancies for catalytic activity. [37][38][39][40] While kinetics of these processes was recently measured by Petrik and Kimmel, 41 the influence of static electric field on oxygen vacancies at anatase (101) surface was studied by Selcuk and Selloni.…”

Section: Introductionmentioning

confidence: 99%

Oscillating electric-field effects on adsorbed-water at rutile- and anatase-TiO2 surfaces

Futera

English

2016

The Journal of Chemical Physics

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We have performed non-equilibrium molecular dynamics simulations of various TiO/water interfaces at ambient temperature in presence of oscillating electric fields in frequency range 20-100 GHz and RMS intensities 0.05-0.25 V/Å. Although the externally applied fields are by one order of magnitude lower than the intrinsic electric field present on the interfaces (∼1.5-4.5 V/Å), significant non-thermal coupling of rotational and translational motion of water molecules was clearly observed. Enhancement of the motion, manifested by increase of diffusivity, was detected in the first hydration layer, which is known to be heavily confined by adsorption to the TiO surface. Interestingly, the diffusivity increases more rapidly on anatase than on rutile facets where the adsorbed water was found to be more organized and restrained. We observed that the applied oscillating field reduces number of hydrogen bonds on the interface. The remaining H-bonds are weaker than those detected under zero-field conditions; however, their lifetime increases on most of the surfaces when the low-frequency fields are applied. Reduction of adsorption interaction was observed also in IR spectra of interfacial water where the directional patterns are smeared as the intensities of applied fields increase.

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Tracking hydroxyl adsorption on TiO2 (110) through secondary emission changes

Cited by 17 publications

References 21 publications

The effect of hydration on the UV absorption coefficient of intact melanosomes

The effect of hydration on the UV absorption coefficient of intact melanosomes

Exploring Rutile (110) and Anatase (101) TiO₂ Water Interfaces by Reactive Force-Field Simulations

Oscillating electric-field effects on adsorbed-water at rutile- and anatase-TiO2 surfaces

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Tracking hydroxyl adsorption on TiO2 (110) through secondary emission changes

Cited by 17 publications

References 21 publications

The effect of hydration on the UV absorption coefficient of intact melanosomes

The effect of hydration on the UV absorption coefficient of intact melanosomes

Exploring Rutile (110) and Anatase (101) TiO2 Water Interfaces by Reactive Force-Field Simulations

Oscillating electric-field effects on adsorbed-water at rutile- and anatase-TiO2 surfaces

Contact Info

Product

Resources

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Exploring Rutile (110) and Anatase (101) TiO₂ Water Interfaces by Reactive Force-Field Simulations