Unstable Single‐Layered Colloidal TiS<sub>2</sub> Nanodisks

Park, Kang Hyun; Choi, Jaewon; Kim, Hae Jin; Oh, Dong‐Hwa; Ahn, Joung Real; Son, Seung Uk

doi:10.1002/smll.200700804

Cited by 88 publications

(68 citation statements)

References 58 publications

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“…Interestingly enough, the reproduction factors calculated for 1T‐MoS 2 →2H‐MoS 2 reactions are smaller and energy barriers are one order higher than those discovered for titanium disulfide TiS 2 (3.75 and 0.12 eV) . This can explain the fact that both 1T and 2H forms of MoS 2 are observed in experiments and both forms are quite stable in the absence of external impacts, while 2H form of TiS 2 is quite unstable and can be seen only in some specific conditions like colloidal nanodisks . Note also that 1T form is more stable in TiS 2 while 2H form is more stable in MoS 2 .…”

Section: Resultsmentioning

confidence: 78%

Solid‐state reaction as a mechanism of 1T ↔ 2H transformation in MoS₂ monolayers

et al. 2015

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Monolayers of molybdenum disulfide MoS2 are considered to be prospective materials for nanoelectronics and various catalytic processes. Since in certain conditions they undergo 1T ↔ 2H phase transitions, studying these phase changes is an urgent task. We present a DFT research of these transitions to show that they can proceed as a solid-state reaction. Two transition states were discovered with energy barriers 1.03 and 1.40 eV. Sulfur atoms in the transition states are shown to be displaced relative to molybdenum atoms so that a tendency of one structural modification to transform into the other modification is seen. This kind of displacements agrees with electron microscopy data reported earlier. The energy parameters indicate that 1T → 2H reactions are exothermic for both transition states and can possibly proceed in a self-sustained manner when initially activated by some external energy impact.

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Section: Resultsmentioning

confidence: 78%

Solid‐state reaction as a mechanism of 1T ↔ 2H transformation in MoS₂ monolayers

et al. 2015

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“…Only kinetic reasons hinder its formation. 34 Previous theoretical calculations have shown that such 2D TiO 2 phase is metastable against various 3D forms, 35 but to our knowledge an isolated 2D-TiO 2 nanostructure has never been synthetized. Using a relatively large 6 × 6 supercell (and a grid of 4 × 4 k-points to sample the Brillouin zone) we have also evaluated the pairing energy between couples of O substituents.…”

Section: Tis 2 Monolayers: Structure and Thermodynamics Of Oxidationmentioning

confidence: 89%

Electronic Properties and Chemical Reactivity of TiS₂ Nanoflakes

et al. 2015

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Transition metal dichalcogenides have a laminar structure, with strongly covalently bonded layers weakly interacting through van der Waals forces. They are of special interest also because of their unique properties once exfoliated in nanoflakes. We analyse the microstructure of oxidised TiS 2 nanoflakes with atomically resolved scanning transmission electron microscopy and propose a comprehensive model for their reactivity by means of first principles simulations. In particular we find that reaction to water proceeds from the edges of the flake, while it is thermodynamically possible but kinetically hindered in the middle, unless it is initiated by the presence of a surface vacancy. Importantly O substitution for S allows fine-tuning control of the flake bandgap, paving the way for the use of TiS 2-x O x alloys as surface catalysts and photovoltaic materials. . High-resolution image of a TiS 2 flake edge showing an extended crystalline region in the upper part. The bright dots in the image correspond to Ti atoms surrounded by S atoms. Below the dotted line an area of amorphous TiO2 is indicated. In the magnified HAADF image (blue box in the image) the Ti and S atom columns are well separated. Beside the HAADF image we present the corresponding Electron Energy Loss (EEL) spectrum images (elemental maps) of S, C, Ti and O respectively (left to right) for the same region. These elemental maps confirm that the bright areas in the HAADF STEM image are indeed Ti atoms, surrounded by S. In the part of the The O signal is predominantly localised at the edge (dotted region). Some C contamination can be seen, especially at the edge. b) FFT of Survey image in (a) (gamma set to 0.4 to suppress the background) and c) the EELS sum-spectrum used to produce the elemental maps presented in (a). The low signal to background ratio at the O edge explains the noise in the O-map..

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“…Titanium Disulfide (TiS 2 ) is a metallic thermoelectric material which attains unique morphologies such as nanotubes, nanoclusters and nanodisks, and exhibits interesting physical properties. [187][188][189][190][191][192][193][194][195][196][197][198] Meng et al 199 has prepared 2D TiS 2 nanosheets decorated on graphene using a ball milling method and followed by high-temperature annealing. photoanode for a DSSC was prepared by immersing it in N719 dye solution for 24 hours at room temperature.…”

Section: Tis 2 Counter Electrodesmentioning

confidence: 99%

Two-dimensional transition metal dichalcogenide-based counter electrodes for dye-sensitized solar cells

et al. 2017

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Dye-sensitized solar cells (DSSCs) are gaining considerable interest as alternatives to semiconductor-based thin film solar cells. The noble metal platinum (Pt) is conventionally used as a counter electrode (CE) material for fabricating DSSCs, since Pt is expensive and scarce, therefore, new materials have been explored to develop cost-effective Pt-free counter electrodes. Two-dimensional (2D) graphene-based counter electrodes have achieved the highest power conversion efficiency (PCE, h) of 13%, which has stimulated research activities in 2D layered transition metal dichalcogenides (TMDs) for developing Pt-free DSSCs.In this review, progress made on alternative counter electrodes for fabricating low-cost Pt-free DSSCs, based on earth-abundant 2D TMDs including MoS

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Unstable Single‐Layered Colloidal TiS₂ Nanodisks

Abstract: Single‐layered titanium sulfide nanodisks (see image) are prepared for the first time using the wet chemical method. The size of the nanodisks are controlled by changing the experimental conditions. The synthesized nanodisks show interesting structural changes at room temperature.

Cited by 88 publications

References 58 publications

Solid‐state reaction as a mechanism of 1T ↔ 2H transformation in MoS₂ monolayers

Solid‐state reaction as a mechanism of 1T ↔ 2H transformation in MoS₂ monolayers

Electronic Properties and Chemical Reactivity of TiS₂ Nanoflakes

Two-dimensional transition metal dichalcogenide-based counter electrodes for dye-sensitized solar cells

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Unstable Single‐Layered Colloidal TiS2 Nanodisks

Abstract: Single‐layered titanium sulfide nanodisks (see image) are prepared for the first time using the wet chemical method. The size of the nanodisks are controlled by changing the experimental conditions. The synthesized nanodisks show interesting structural changes at room temperature.

Cited by 88 publications

References 58 publications

Solid‐state reaction as a mechanism of 1T ↔ 2H transformation in MoS2 monolayers

Solid‐state reaction as a mechanism of 1T ↔ 2H transformation in MoS2 monolayers

Electronic Properties and Chemical Reactivity of TiS2 Nanoflakes

Two-dimensional transition metal dichalcogenide-based counter electrodes for dye-sensitized solar cells

Contact Info

Product

Resources

About

Unstable Single‐Layered Colloidal TiS₂ Nanodisks

Solid‐state reaction as a mechanism of 1T ↔ 2H transformation in MoS₂ monolayers

Solid‐state reaction as a mechanism of 1T ↔ 2H transformation in MoS₂ monolayers

Electronic Properties and Chemical Reactivity of TiS₂ Nanoflakes