Surfactant‐Free Polar‐to‐Nonpolar Phase Transfer of Exfoliated MoS<sub>2</sub> Two‐Dimensional Colloids

Giovanelli, Emerson; Castellanos-Gómez, Andrés; Pérez, Emilio M.

doi:10.1002/cplu.201700038

Cited by 13 publications

(9 citation statements)

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“…The transfer to ACN of the exfoliated MoS 2 was done following a protocol described previously, then N ‐benzylmaleimide (Bn‐mal) and triethylamine (Et 3 N) were added and the mixture was stirred overnight. The mixture was washed with ACN and i PrOH to remove all physisorbed Bn‐mal, which was confirmed by UV/Vis of the residues (Figure S5).…”

Section: Resultssupporting

confidence: 79%

Controlled Covalent Functionalization of 2 H‐MoS₂ with Molecular or Polymeric Adlayers

Quirós‐Ovies

Sulleiro

Vera-Hidalgo

et al. 2020

Chemistry A European J

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Most air-stable 2D materials are relativelyi nert, which makes their chemicalm odification difficult. In particular,i nt he case of MoS 2 ,t he semiconducting 2H-MoS 2 is much less reactive than itsm etallicc ounterpart, 1T-MoS 2 .A s ac onsequence, there are hardly any reliable methods for the covalent modification of 2H-MoS 2 .A ni deal method for the chemical functionalization of such materials should be both mild, not requiring the introductiono falarge number of defects, and versatile, allowing for the decoration with as many different functional groups as possible. Herein, ac omprehensive study on the covalentf unctionalization of 2H-MoS 2 with maleimidesi sp resented. The use of ab ase (Et 3 N) leads to the in situ formationo fasuccinimide polymer layer, covalently connected to MoS 2 .I nc ontrast, in the absence of base, functionalization stops at the molecular level.M oreover,t he functionalization protocol is mild (occursa tr oom temperature), fast (nearlyc omplete in 1h), and very flexible (11different solvents and 10 different maleimides tested). In practical terms, the procedures described here allow for the chemistt om anipulate 2H-MoS 2 in av ery flexible way,d ecorating it with polymers or molecules, and with aw ide range of functional groups fors ubsequent modification. Conceptually,t he spurious formationo fa no rganic polymerm ight be general to other methods of functionalization of 2D materials, where al arge excesso fm olecular reagents is typically used.

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Section: Resultssupporting

confidence: 79%

Controlled Covalent Functionalization of 2 H‐MoS₂ with Molecular or Polymeric Adlayers

Quirós‐Ovies

Sulleiro

Vera-Hidalgo

et al. 2020

Chemistry A European J

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“…The peaks for MoS 2 at 685 and 622 nm are ascribed to the direct band-to-band excitonic transition at the K-point, whereas peaks at 395 and 490 nm are assigned to the direct transition from the deep valence band to the conduction band, between the Γ and Λ points of the Brillouin zone. 45,46 After the solvothermal treatment, these four characteristic peaks are found to be diminished with the appearance of a new broad absorption peak near the UV region, around 300−400 nm. These new peaks are attributed to the excitonic transition from the TMD QDs as shown in Figure 1a (red and black), as a result of the quantum confinement effect owing to their reduction in size approaching the excitonic Bohr radius, and hence an increase in the band gap is expected.…”

Section: Resultsmentioning

confidence: 99%

Tunable Conductance of MoS₂ and WS₂ Quantum Dots by Electron Transfer with Redox-Active Quinone

Behera

Mishra

Panigrahi

et al. 2022

ACS Appl. Mater. Interfaces

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Due to their uniqueness in tunable photophysics, transition metal dichalcogenide (TMD) based quantum dots (QDs) have emerged as the next-generation quantum materials for technology-based semiconductor applications. This demands frontline research on the rational synthesis of the TMD QDs with controlled shape, size, nature of charge migration at the interface, and their easy integration in optoelectronic devices. In this article, with a controlled solution-processed synthesis of MoS 2 and WS 2 QDs, we demonstrate the disparity in their structural, optical, and electrical characteristics in bulk and confinement. With a series of steady-state and time-resolved spectroscopic measurements in different media, we explore the uncommon photophysics of MoS 2 and WS 2 QDs such as excitation-dependent photoluminescence and assess their excited state charge transfer kinetics with a redox-active biomolecule, menadione (MQ). In comparison to the homogeneous aqueous medium, photoinduced charge transfer between the QDs and MQ becomes more plausible in encapsulated cetyltrimethylammonium bromide (CTAB) micelles. Current sensing atomic force microscopy (CS-AFM) measurements at a single molecular level reveal that the facilitated charge transfer of QDs with MQ strongly correlates with an enhancement in their charge transport behavior. An increase in charge transport further depends on the density of states of the QDs directing a change in Schottky emission to Fowler−Nordheim (FN) type of tunneling across the metal−QD−metal junction. The selective response of the TMD QDs while in proximity to external molecules can be used to design advanced optoelectronic devices and applications involving rectifiers and tunnel diodes for future quantum technology.

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“…However, the challenges involved with a stable dispersion of nanomaterials (0D, 1D, and 2D) in such systems are nontrivial, as reported. − There are several examples of a stable MoS 2 dispersion in organic solvents − and its functionalization with organic ligands. − These reports mainly discuss either direct covalent functionalization of MoS 2 by organic ligands containing various functional groups such as thiols, halides, and diazonium salts or, on the other hand, surfactant assisted exfoliation. , At this point there have been several reports highlighting efficacious methods for liquid phase exfoliation of MoS 2 resulting in high-quality single- and few-nanosheet dispersions. While the stability of nanomaterials in simple fluids (e.g., water, organic solvents) can be secured using a variety of surface-active species, ensuring stability in structured fluids (i.e., nematic, or smectic liquid crystals) is challenging due to nanomaterials’ distortion of the fluid’s director field by the nanomaterials, and their tendency to aggregate to minimize that deformation. − Concerning MoS 2 in particular, we are unaware of any successful examples of a stable dispersion in thermotropic LCs.…”

mentioning

confidence: 99%

Nanocomposites of 2D-MoS₂ Exfoliated in Thermotropic Liquid Crystals

Gabinet

Lee

Poling-Skutvik

et al. 2021

ACS Materials Lett.

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Atomically thin MoS 2 nanosheets are of interest due to unique electronic, optical, and catalytic properties that are absent in the bulk material. Methods to prepare nanosheets from bulk material that facilitate studies of 2D-MoS 2 and the fabrication of useful devices have consequently assumed considerable importance. Here, we report the simultaneous exfoliation and stable dispersion of MoS 2 nanosheets in a liquid crystal. Exfoliation of bulk MoS 2 in mesogen-containing solutions produced stable dispersions of 2D-MoS 2 that retained suspension stability for several weeks. Solvent removal in cast films yielded nanocomposites of 2D-MoS 2 . Preservation of single-and few-sheet MoS 2 was confirmed utilizing UV−vis and Raman spectroscopy in the nematic and isotropic fluid states of the system and, remarkably, in the solid crystal as well. Importantly, the MoS 2 nanosheets remained welldispersed upon polymerization of the reactive mesogen to form a liquid crystal polymer. The ability to stably disperse 2D-MoS 2 in a structured fluid opens up new possibilities for studying anisotropic properties of MoS 2 and for exploiting such properties in responsive materials.

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Surfactant‐Free Polar‐to‐Nonpolar Phase Transfer of Exfoliated MoS₂ Two‐Dimensional Colloids

Cited by 13 publications

References 50 publications

Controlled Covalent Functionalization of 2 H‐MoS₂ with Molecular or Polymeric Adlayers

Controlled Covalent Functionalization of 2 H‐MoS₂ with Molecular or Polymeric Adlayers

Tunable Conductance of MoS₂ and WS₂ Quantum Dots by Electron Transfer with Redox-Active Quinone

Nanocomposites of 2D-MoS₂ Exfoliated in Thermotropic Liquid Crystals

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Surfactant‐Free Polar‐to‐Nonpolar Phase Transfer of Exfoliated MoS2 Two‐Dimensional Colloids

Cited by 13 publications

References 50 publications

Controlled Covalent Functionalization of 2 H‐MoS2 with Molecular or Polymeric Adlayers

Controlled Covalent Functionalization of 2 H‐MoS2 with Molecular or Polymeric Adlayers

Tunable Conductance of MoS2 and WS2 Quantum Dots by Electron Transfer with Redox-Active Quinone

Nanocomposites of 2D-MoS2 Exfoliated in Thermotropic Liquid Crystals

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Surfactant‐Free Polar‐to‐Nonpolar Phase Transfer of Exfoliated MoS₂ Two‐Dimensional Colloids

Controlled Covalent Functionalization of 2 H‐MoS₂ with Molecular or Polymeric Adlayers

Controlled Covalent Functionalization of 2 H‐MoS₂ with Molecular or Polymeric Adlayers

Tunable Conductance of MoS₂ and WS₂ Quantum Dots by Electron Transfer with Redox-Active Quinone

Nanocomposites of 2D-MoS₂ Exfoliated in Thermotropic Liquid Crystals