Frequency modulation atomic force microscope observation of TiO2(110) surfaces in water

Sasahara, Akira; Tomitori, Masahiko

doi:10.1116/1.3294707

Cited by 10 publications

(16 citation statements)

References 26 publications

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“…A UHV‐STM study of TiO 2 (110) before and after dipping the sample in water indicated that the surface might not be stable . This was also observed with atomic force microscope (AFM) measurements in liquid …”

Section: Introductionmentioning

confidence: 69%

Molecular Ordering at the Interface Between Liquid Water and Rutile TiO₂(110)

Serrano

Bonanni

Giovannantonio

et al. 2015

Adv Materials Inter

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The pivotal importance of TiO2 as a technological material involves most applications in an aqueous environment, but the single‐crystal TiO2/bulk‐water interfaces are almost completely unexplored, since up to date solid/liquid interfaces are more difficult to access than surfaces in ultrahigh vacuum (UHV). Only a few techniques (as scanning probe microscopy) offer the opportunity to explore these systems under realistic conditions. The rutile TiO2(110) surface immersed in high‐purity water is studied by in situ scanning tunneling microscopy. The large‐scale surface morphology as obtained after preparation under UHV conditions remains unchanged upon prolonged exposure to bulk water. Moreover, in contrast to UHV, atomically resolved images show a twofold periodicity along the [001] direction, indicative of an ordered structure resulting from the hydration layer. This is consistent with density‐functional theory based molecular dynamics simulations where neighboring interfacial molecules of the first water layer in contact with the bulk liquid form dimers. By contrast, this dimerization is not observed for a single adsorbed water monolayer, i.e., in the absence of bulk water.

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Section: Introductionmentioning

confidence: 69%

Molecular Ordering at the Interface Between Liquid Water and Rutile TiO₂(110)

Serrano

Bonanni

Giovannantonio

et al. 2015

Adv Materials Inter

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“…The high density of OH t groups (0.9 nm −2 ) was probably achieved by the dissociation of H 2 O molecules. The presence of a hydrogen-bonding network near the surface 22 suggests that a high density of H 2 O molecules coordinate to the O b and Ti 5c atoms, thereby forming the underlying structure for the hydration layer. Some of the OH t groups might associatively desorb, thus leaving O a atoms 18…”

Section: ■ Experimental Methodsmentioning

confidence: 99%

“…This observation suggests retention of the (1 × 1) structure of the terraces upon its brief exposure to air. We also explored the imaging of the (1 × 1) surface immersed in water by noncontact atomic force microscopy (NC-AFM) . O b atom rows appeared, along with nanosized particles, hypothesized to be H 2 O clusters, aligned along the [001] direction.…”

Section: Introductionmentioning

confidence: 99%

An Atomic-Scale Study of TiO₂(110) Surfaces Exposed to Humid Environments

Sasahara

Tomitori

2016

J. Phys. Chem. C

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Rutile titanium dioxide (TiO 2 ) ( 110)-(1 × 1) surfaces prepared in an ultrahigh vacuum (UHV) were transferred to humid environments and thereafter returned to UHV to be examined by the scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) techniques. STM images showed that hydroxyl groups terminating 5-foldcoordinated Ti atoms (OH t groups) and hydroperoxyl (OOH) groups, with densities of 0.9 and 0.2 nm −2 , respectively, formed after exposure to water vapor at a pressure of several tens of pascals. The density of the OH t groups was found to exceed that predicted when they were assumed to have originated from another type of OH groups involved in bridging O atoms (OH b groups) intrinsically present on the (1 × 1) surface. On the basis of this observation, we hypothesize that dissociation of H 2 O molecules by evacuation of the water layer produces OH t groups. The OH b groups, produced with the OH t groups by this dissociation, react with O 2 molecules dissolved in the water layer, forming OOH groups. Surfaces exposed to laboratory air or immersed in liquid water were also found to be rich in OH t groups; consequently, evacuation-induced processes occurred on those surfaces. Clarification of the effects of evacuation of the water layer implies the possibility of characterizing (1 × 1) surfaces in humid environments by ex situ analysis under UHV.

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“…FM-AFM imaging in liquids has been used for various samples, ranging from inorganic crystals , to biomolecules. , As mentioned above, atomic-scale AFM investigations of rutile and anatase TiO 2 in vacuum have already been reported. However, although AFM images with atomic-scale striped contrasts obtained at the rutile (110) surface in liquid have been reported, the contrasts within each stripe were not clear enough to allow their detailed comparison with an atomic surface model. To the best of our knowledge, there has been no report of atomic-scale AFM studies of TiO 2 surfaces in liquids, not only of brookite, but also of rutile and anatase.…”

Section: Introductionmentioning

confidence: 99%

Direct Imaging of Atomic-Scale Surface Structures of Brookite TiO₂ Nanoparticles by Frequency Modulation Atomic Force Microscopy in Liquid

et al. 2018

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1Direct imaging of atomic-scale surface structures of TiO 2 nanoparticles is a promis-2 ing method for understanding the detailed mechanism of their photocatalytic activities. 3 Atomic force microscopy (AFM) is one of the analytical tools used for direct imaging 4 of surfaces, but atomic-scale AFM studies of TiO 2 nanoparticles in a liquid have not 5 been reported. Here, we report two methods for fixing of TiO 2 nanocrystals: an elec-6 trostatic method and a cross-linking method. Both methods enabled visualization of 7 subnanoscale surface structures of brookite TiO 2 nanoparticles in a liquid by frequency 8 modulation AFM (FM-AFM). The FM-AFM imaging results and density functional 9 theory molecular dynamics calculations suggest that the subnanoscale structures in the 10 FM-AFM images can be explained by the arrangement of the surface topmost atoms 11 or their hydration structures on the brookite TiO 2 (210) surface. Our results open 12 up various possibilities for studying atomic-scale surface structures of nanoparticles in 13 liquids by AFM.14

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Frequency modulation atomic force microscope observation of TiO2(110) surfaces in water

Abstract: Scanning tunneling microscopic analysis of Cu ( In , Ga ) Se 2 epitaxial layers J. Appl. Phys. 107, 034906 (2010); 10.1063/1.3304919 Ferroelectric relaxor behavior and microwave dielectric properties of Ba ( Zr 0.3 Ti 0.7 ) O 3 thin films grown by radio frequency magnetron sputtering

Cited by 10 publications

References 26 publications

Molecular Ordering at the Interface Between Liquid Water and Rutile TiO₂(110)

Molecular Ordering at the Interface Between Liquid Water and Rutile TiO₂(110)

An Atomic-Scale Study of TiO₂(110) Surfaces Exposed to Humid Environments

Direct Imaging of Atomic-Scale Surface Structures of Brookite TiO₂ Nanoparticles by Frequency Modulation Atomic Force Microscopy in Liquid

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Frequency modulation atomic force microscope observation of TiO2(110) surfaces in water

Abstract: Scanning tunneling microscopic analysis of Cu ( In , Ga ) Se 2 epitaxial layers J. Appl. Phys. 107, 034906 (2010); 10.1063/1.3304919 Ferroelectric relaxor behavior and microwave dielectric properties of Ba ( Zr 0.3 Ti 0.7 ) O 3 thin films grown by radio frequency magnetron sputtering

Cited by 10 publications

References 26 publications

Molecular Ordering at the Interface Between Liquid Water and Rutile TiO2(110)

Molecular Ordering at the Interface Between Liquid Water and Rutile TiO2(110)

An Atomic-Scale Study of TiO2(110) Surfaces Exposed to Humid Environments

Direct Imaging of Atomic-Scale Surface Structures of Brookite TiO2 Nanoparticles by Frequency Modulation Atomic Force Microscopy in Liquid

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Molecular Ordering at the Interface Between Liquid Water and Rutile TiO₂(110)

Molecular Ordering at the Interface Between Liquid Water and Rutile TiO₂(110)

An Atomic-Scale Study of TiO₂(110) Surfaces Exposed to Humid Environments

Direct Imaging of Atomic-Scale Surface Structures of Brookite TiO₂ Nanoparticles by Frequency Modulation Atomic Force Microscopy in Liquid