Oxygen vacancies on TiO2(110) and their interaction with H2O and O2: A combined high-resolution STM and DFT study

Wendt, Stefan; Schaub, Renald; Matthiesen, J.; Vestergaard, Ebbe K.; Wahlström, Erik; Rasmussen, M. D.; Thostrup, Peter; Molina, L. M.; Lægsgaard, Erik; Stensgaard, I.; Hammer, Bjørk; Besenbacher, Flemming

doi:10.1016/j.susc.2005.08.041

Cited by 577 publications

(751 citation statements)

References 53 publications

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“…The OH groups on the TiO 2 (110) surface were spontaneously created from the dissociation of water molecules (from background residual gas) over the oxygen vacancy sites by transferring an H atom to neighboring O b sites. 5 By keeping the freshly prepared sample in UHV more than 4 h, all of the O vacancies are occupied by OHs. Thus, in our measurements, only the OH groups are considered as surface impurity defects.…”

Section: A Experimental Detailsmentioning

confidence: 99%

“…The flexibility of the tip controls the energetics of such relaxation at the apex. Due to the computational cost, we have modeled it with a small (TiO 2 ) 5 cluster where only the last five atoms were allowed to relax [see Fig. 2(b)].…”

Section: A Protrusion Mode Forcesmentioning

confidence: 99%

“…Scanning tunneling microscopy (STM) images usually show perfect bright rows, identified with Ti 5c , 4 and bright, localized features in between that have been associated with two defect species [oxygen vacancies and hydroxyl (OH) groups] located on the O b rows. 5,6 At variance with STM, atomic force microscopy with true atomic resolution [known as noncontact (nc)-AFM 7 ] has revealed a number of qualitatively different contrast modes. [8][9][10][11][12] Most images show either a contrast similar to STM with Ti 5c rows and defects imaged bright and O b rows imaged dark (protrusion mode), or its complete reversal (O b bright and Ti 5c rows and defects appearing dark), called hole mode.…”

Section: Introductionmentioning

confidence: 99%

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Understanding image contrast formation in TiO2with force spectroscopy

et al. 2012

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Site-specific force measurements on a rutile TiO 2 (110) surface are combined with first-principles calculations in order to clarify the origin of the force contrast and to characterize the tip structures responsible for the two most common imaging modes. Our force data, collected over a broad range of distances, are only consistent with a tip apex contaminated with clusters of surface material. A flexible model tip terminated with an oxygen explains the protrusion mode. For the hole mode we rule out previously proposed Ti-terminated tips, pointing instead to a chemically inert, OH-terminated apex. These two tips, just differing in the terminal H, provide a natural explanation for the frequent contrast changes found in the experiments. As tip-sample contact is difficult to avoid while imaging oxide surfaces, we expect our tip models to be relevant to interpret scanning probe studies of defects and adsorbates on TiO 2 and other technologically relevant metal oxides.

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Section: A Experimental Detailsmentioning

confidence: 99%

Section: A Protrusion Mode Forcesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Understanding image contrast formation in TiO2with force spectroscopy

et al. 2012

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“…[42,43] Research on the complex interactions between water molecules and metal surfaces are widely investigated, which could be applied for interpreting related surface reactions and dynamics of water dissociation. [44][45][46][47] However, when it comes to rough interfaces, wettability will be changed dramatically. For example, there is always a θ IWT on a specific flat solid surface which is regarded as the www.advmat.de www.advancedsciencenews.com limit between lyophilicity and lyophobicity for a given kind of liquid, as shown in Figure 2a.…”

Section: The θ Iwt Of Liquidsmentioning

confidence: 99%

Superlyophilic Interfaces and Their Applications

et al. 2017

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Superlyophilic interfaces denote interfaces displaying strong affinity to diverse liquids, including superhydrophilic, superoleophilic, and superamphiphilic interfaces. When coming in contact with these interfaces, water or oil droplets tend to spread completely with contact angles close to 0°, presenting versatile applications including self‐cleaning, antifogging, controllable liquid transport, liquid separation, and so forth. Inspired by nature, scientists have developed various kinds of artificial superlyophilic (SLPL) interfaces in the past decades. In terms of dimensional characteristics, the artificial SLPL interfaces can be divided into four categories: i) 0D particles, whose dispersibility or catalytic performance can be notably enhanced by superlyophilicity; ii) 1D micro‐/nanofibers or nanotubes/channels, which can efficiently transfer liquids with SLPL interfaces; iii) 2D flat SLPL interfaces, on which different functional molecules can be deposited uniformly, forming ultrathin and smooth films; and iv) 3D structures, which can be obtained by either constructing 0D, 1D, or 2D SLPL materials separately or directly fabricating random SLPL frameworks, and can always be used as functional coatings or bulk materials. Here, natural and artificial SLPL interfaces are briefly introduced, followed by a short discussion of the limit between lyophilicity and lyophobicity, and then a snapshot of methods to generate SLPL interfaces is given. Specific focus is placed on recent achievements of constructing SLPL interfaces from zero to three dimensions. Following that, broad applications of SLPL interfaces in commercial areas will be introduced. Finally, a short summary and outlook for future challenges in this field is presented.

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“…Both experimental and theoretical studies have shown that many of the unique properties of metal oxides arise as a result of the complex surface chemistry and the presence of lattice vacancies, which significantly perturb their electronic structure. [1][2][3] Studies on both pure and reduced anatase TiO 2 and CeO 2 surfaces showed that nonstoichiometric or reduced surfaces have an increased number of surface and subsurface oxygen vacancies. [4][5][6] These sites act as low energy binding sites for absorption of O 2 and H 2 O molecules, and are critical to the enhancement of catalytic activity.…”

Section: Introductionmentioning

confidence: 99%

Modulation of stoichiometry, morphology and composition of transition metal oxide nanostructures through hot wire chemical vapor deposition

et al. 2015

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A hot wire chemical vapor deposition technique is described for synthesis of 1D nanostructures of a controlled morphology, stoichiometry, and composition. The synthesis involves the evaporation and condensation of metal oxide vapor through the reaction of oxygen with the hot filaments of respective transition metals. The stoichiometry and morphology of MoO 3 and WO 3 were modulated by varying the filament temperature and partial pressure of oxygen in the growth chamber. Based on the results under different conditions, a morphological phase diagram, and a growth model based on the extent of gas phase supersaturation were developed to understand the growth mechanism. Further, ternary transition metal oxide, NiMoO 4, was synthesized as a proof-of-concept for tuning the composition of deposition through simultaneous evaporation of two metal oxides.

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Oxygen vacancies on TiO2(110) and their interaction with H2O and O2: A combined high-resolution STM and DFT study

Cited by 577 publications

References 53 publications

Understanding image contrast formation in TiO2with force spectroscopy

Understanding image contrast formation in TiO2with force spectroscopy

Superlyophilic Interfaces and Their Applications

Modulation of stoichiometry, morphology and composition of transition metal oxide nanostructures through hot wire chemical vapor deposition

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