Structure and Energetics of Water Adsorbed at<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>TiO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>Anatase \(101\) and \(001\) Surfaces

Vittadini, Andrea; Selloni, Annabella; Rotzinger, François P.; Grätzel, Michaël

doi:10.1103/physrevlett.81.2954

Cited by 916 publications

(828 citation statements)

References 21 publications

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“…The surfaces of anatase particles consist predominantly of (1 0 1), (1 0 0) and (0 0 1) crystal planes [30,31], with the specific expression of crystal planes (i.e., the crystal habit) depending on the synthesis technique [32,33]. The crystal planes and model cluster were also selected based on the good agreement of calculated As-O and As-Ti distances with our experimental EX-AFS results.…”

Section: Methods and Theorymentioning

confidence: 99%

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Studies on the reaction pathway of arsenate adsorption at water–TiO2 interfaces using density functional theory

Pan

Zhang

2011

Journal of Colloid and Interface Science

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a b s t r a c tReaction pathway information of transition states and intermediate species is crucial for understanding the adsorption mechanism of pollutants at mineral-water interfaces. However, it has been difficult to obtain such information using existing experiments. Here, the activation barriers, transition states, intermediate species and surface complexes of arsenate adsorption on TiO 2 surfaces were studied using DFTbased reaction pathway calculations. The results indicated that the bidentate binuclear (BB) adsorption structure was formed through a monodentate mononuclear (MM) metastable-equilibrium adsorption (MEA) state. A two-step adsorption mechanism was proposed on the basis of the detailed picture of bond breaking and bond formation during each reaction step. When the adjacent surface sites were occupied, the transform from MM mode to BB mode was greatly inhibited so that both MM and BB coexisted in the equilibrium adsorption sample. The BB complex was energetically more stable than the MM complex, and so, the adsorption irreversibility was fundamentally related to the ratio BB:MM in the final equilibrium state. This mechanism may also explain the initial concentration effect, where, for the given adsorption experiment of arsenate on TiO 2 under the same thermodynamic conditions, both equilibrium constants and the BB:MM ratio in equilibrium adsorption samples changed with the reaction kinetics.

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Section: Methods and Theorymentioning

confidence: 99%

“…3a). Such electronic structures indicated that the Ti atoms were the surface reactive sites to bond with water molecules and form the surface functional groups (i.e., hydrated surfaces) in aqueous solutions [11,31,39]. For the hydrated TiO 2 surfaces, the calculated surface Ti-O distances were 2.06 Å (Fig.…”

Section: Reactivity Of Hydrated Tio 2 Surfacesmentioning

confidence: 96%

Studies on the reaction pathway of arsenate adsorption at water–TiO2 interfaces using density functional theory

Pan

Zhang

2011

Journal of Colloid and Interface Science

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“…as H + and OH -) against the nondissociative water adsorption to rutile faces (i.e. as H 2 O) Vittadini et al 1998). Oxygen in the form of O 2 -, O -and dissociated water molecules on the anatase crystal faces facilitate the ROS formation (Sclafani and Herrmann 1996).…”

Section: Discussionmentioning

confidence: 99%

Does nanoparticle activity depend upon size and crystal phase?

et al. 2008

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A method to investigate the dependence of the physicochemical properties of nanoparticles (e.g. size, surface area and crystal phase) on their oxidant generating capacity is proposed and demonstrated for TiO 2 nanoparticles. Gas phase synthesis methods that allow for strict control of size and crystal phase were used to prepare TiO 2 nanoparticles. The reactive oxygen species (ROS) generating capacity of these particles was then measured. The size dependent ROS activity was established using TiO 2 nanoparticles of 9 different sizes (4 -195 nm) but the same crystal phase. For a fixed total surface area, an S-shaped curve for ROS generation per unit surface area was observed as a function of particle size. The highest ROS activity per unit area was observed for 30 nm particles, and observed to be constant above 30 nm. There was a decrease in activity per unit area as size decreased from 30 nm to 10 nm; and again constant for particles smaller than 10 nm. The correlation between crystal phase and oxidant capacity was established using TiO 2 nanoparticles of 11 different crystal phase combinations but similar size. The ability of different crystal phases of TiO 2 nanoparticles to generate ROS was highest for amorphous, followed by anatase, and then anatase/rutile mixtures, and lowest for rutile samples. Based on evaluation of the entire dataset, important dose metrics for ROS generation are established. Their implications of these ROS studies on biological and toxicological studies using nanomaterials are discussed.

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“…The {001} facets have two times higher surface energy than {101} facets, but is expected to exhibit higher reactivity [16]. Ab initio calculations show that water dissociates on the (001) surface, while it only adsorbs molecularly on the (101) [17]. Altering the preparation conditions it was found that TiO 2 nanoparticles made by solvothermal synthesis can be prepared with altered <001>/<101> facet ratio [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Tuning the Photocatalytic Activity of Anatase TiO2 Thin Films by Modifying the Preferred <001> Grain Orientation with Reactive DC Magnetron Sputtering

Stefanov

Österlund

2014

Coatings

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Anatase TiO 2 thin films were deposited by DC reactive magnetron sputtering on glass substrates at 20 mTorr pressure in a flow of an Ar and O 2 gas mixture. The O 2 partial pressure (P O2 ) was varied from 0.65 mTorr to 1.3 mTorr to obtain two sets of films with different stoichiometry. The structure and morphology of the films were characterized by secondary electron microscopy, atomic force microscopy, and grazing-angle X-ray diffraction complemented by Rietveld refinement. The as-deposited films were amorphous. Post-annealing in air for 1 h at 500 °C resulted in polycrystalline anatase film structures with mean grain size of 24.2 nm (P O2 = 0.65 mTorr) and 22.1 nm (P O2 = 1.3 mTorr), respectively. The films sputtered at higher O 2 pressure showed a preferential orientation in the <001> direction, which was associated with particle surfaces exposing highly reactive {001} facets. Films sputtered at lower O 2 pressure exhibited no, or very little, preferential grain orientation, and were associated with random distribution of particles exposing mainly the thermodynamically favorable {101} surfaces. Photocatalytic degradation measurements using methylene blue dye showed that <001> oriented films exhibited approximately 30% higher reactivity. The measured intensity dependence of the degradation rate revealed that the UV-independent rate constant was 64% higher for the <001> oriented film compared to randomly oriented films. The reaction order was also found to be higher for <001> films compared to randomly oriented films, suggesting that the <001> oriented film exposes more reactive surface sites.

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Structure and Energetics of Water Adsorbed atTiO2Anatase \(101\) and \(001\) Surfaces

Cited by 916 publications

References 21 publications

Studies on the reaction pathway of arsenate adsorption at water–TiO2 interfaces using density functional theory

Studies on the reaction pathway of arsenate adsorption at water–TiO2 interfaces using density functional theory

Does nanoparticle activity depend upon size and crystal phase?

Tuning the Photocatalytic Activity of Anatase TiO2 Thin Films by Modifying the Preferred <001> Grain Orientation with Reactive DC Magnetron Sputtering

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