Atomic structure of titania nanosheet with vacancies

Ohwada, Megumi; Kimoto, Koji; Mizoguchi, Teruyasu; Ebina, Yasuo; Sasaki, Takayoshi

doi:10.1038/srep02801

Cited by 63 publications

(61 citation statements)

References 24 publications

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“…The defect formation energy E d for the TiO 2 V model can be estimated by subtracting the energy per formula unit of the Perfect model from that of the TiO 2 V model. The value of E d was obtained to be 3.6 eV, which confirms that the Perfect model is more stable than the TiO 2 V model, though Ti vacancies are introduced in TNSs due to the synthesis method as observed in the TEM experiments [5]. The comparison of the energetic stability between the TiV-H and TiO 2 V models is also possible by calculating the energy gain or loss of the reaction, in which the TiO 2 V model reacts with two H 2 O molecules to form the TiV-H model.…”

Section: A Energetic Stabilitysupporting

confidence: 59%

“…We found that this reaction has the energy gain of 3.0 eV, which indicates that the TiV-H model is more stable than the TiO 2 V model. As explained in Section II.B, the TiO 2 V model seems to be consistent with the observation of the TEM experiments [5]. In our calculations, we did not consider the energy barriers for the reactions, which may be important to discuss which structure actually appears, and will be studied in our future work.…”

Section: A Energetic Stabilitysupporting

confidence: 56%

“…As described in Introduction, the chemical composition of Ti 0.87 O 2 has been expected from the synthesis method. However, we focus on charge neutral systems in this study, as the TEM experiments [5] have suggested that O atoms around a Ti vacancy tend to be removed, which may justify the TiO 2 V model. The charged systems with a deficiency of Ti atoms will be studied in our future work.…”

Section: B Structure Modelsmentioning

confidence: 99%

“…With regard to atomic structures around the Ti vacancies, it has been suggested that two 1-fold coordinated O atoms around the Ti vacancies tend to be removed [5]. However, the atomic configurations around the Ti vacancies have not been definitely determined yet.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, the presence of 13 % Ti vacancies is expected. Actually, the Ti vacancies have been directly observed by transmission electron microscopy (TEM) [5]. However, the effects of the Ti vacancies on the photocatalytic activity have not been revealed yet.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Electronic Structure of Titania Nanosheets with Vacancies Based on First-Principles Calculations

Uchida

Hara

Funatsu

et al. 2018

e-J. Surf. Sci. Nanotech.

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Titania nanosheets (TNSs) are expected to lead to higher photocatalytic performance than bulk TiO2 because its high reactivity arises from the two-dimensional structure. While their electronic properties are considered to be easily affected by structural vacancies, the effects of vacancies in TNSs on the photocatalytic performance are not clear. In order to study them, we have performed first-principles molecular dynamics simulations for structure models of TNSs with several vacancies. First, we have calculated the electronic density of states and bandgap energies Eg. It has been found that Eg of our structure modes of TNSs with vacancies are larger than bulk anatase. This tendency is consistent with the experimentally observed relationship of Eg between TNSs and anatase. It has been clarified from non-adiabatic calculations that the existence of vacancies in TNSs causes spatial charge separation and leads to longer recombination time.

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Section: A Energetic Stabilitysupporting

confidence: 59%

Section: A Energetic Stabilitysupporting

confidence: 56%

Section: B Structure Modelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Electronic Structure of Titania Nanosheets with Vacancies Based on First-Principles Calculations

Uchida

Hara

Funatsu

et al. 2018

e-J. Surf. Sci. Nanotech.

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Atomic‐Level Charge Separation Strategies in Semiconductor‐Based Photocatalysts

et al. 2021

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Semiconductor‐based photocatalysis as a productive technology furnishes a prospective solution to environmental and renewable energy issues, but its efficiency greatly relies on the effective bulk and surface separation of photoexcited charge carriers. Exploitation of atomic‐level strategies allows in‐depth understanding on the related mechanisms and enables bottom‐up precise design of photocatalysts, significantly enhancing photocatalytic activity. Herein, the advances on atomic‐level charge separation strategies toward developing robust photocatalysts are highlighted, elucidating the fundamentals of charge separation and transfer processes and advanced probing techniques. The atomic‐level bulk charge separation strategies, embodied by regulation of charge movement pathway and migration dynamic, boil down to shortening the charge diffusion distance to the atomic‐scale, establishing atomic‐level charge transfer channels, and enhancing the charge separation driving force. Meanwhile, regulating the in‐plane surface structure and spatial surface structure are summarized as atomic‐level surface charge separation strategies. Moreover, collaborative strategies for simultaneous manipulation of bulk and surface photocharges are also introduced. Finally, the existing challenges and future prospects for fabrication of state‐of‐the‐art photocatalysts are discussed on the basis of a thorough comprehension of atomic‐level charge separation strategies.

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Scission of 2D Inorganic Nanosheets via Physical Adsorption on a Nonflat Surface

Sakai

Suzuki

Sasaki

2022

Adv Materials Inter

Self Cite

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Secondary processing of 2D nanosheets is an important technique for fabrication of devices and modulation of properties. However, methods for the secondary processing have not been well developed yet, particularly for the scission along crystallographic orientation. In the present paper, it is reported that titania nanosheets can be orthogonally sectioned into substantially rectangular‐shaped fragments when deposited on a nonflat substrate surface via spin‐coating their suspension. Such events occur for all the nanosheets on the substrate surface. In the deposition process, nanosheets float and stay flat on top of the solvent surface, and adsorb on the substrate with conforming to the bumpy surface by following the descending solvent level. Because the nanosheet area is smaller than the actual area of the bumpy surface having the same projected area, the nanosheet experiences tensile stress along its lateral direction. The tensile stress originates from the intermolecular forces acting between the nanosheet and the substrate surface upon the adsorption on the substrate. Due to the high 2D anisotropy, the integrated intermolecular forces can be large enough to cleave the chemical bonds, leading to the scission of the nanosheet. This interesting finding may offer a new processing technique for cutting and shaping various 2D materials.

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Atomic structure of titania nanosheet with vacancies

Cited by 63 publications

References 24 publications

Electronic Structure of Titania Nanosheets with Vacancies Based on First-Principles Calculations

Electronic Structure of Titania Nanosheets with Vacancies Based on First-Principles Calculations

Atomic‐Level Charge Separation Strategies in Semiconductor‐Based Photocatalysts

Scission of 2D Inorganic Nanosheets via Physical Adsorption on a Nonflat Surface

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