Chemical methods for the exfoliation of transition metal Chemical methods for the exfoliation of transition metal dichalcogenides in a liquid medium to give single-layer dispersions dichalcogenides in a liquid medium to give single-layer dispersions containing quasi-two-dimensional layers of these compounds are containing quasi-two-dimensional layers of these compounds are surveyed. Data on the structure of dispersions and their use in the surveyed. Data on the structure of dispersions and their use in the synthesis of various types of heterolayered intercalation com-synthesis of various types of heterolayered intercalation compounds are discussed and described systematically. Structural pounds are discussed and described systematically. Structural features, the electronic structure and the physicochemical proper-features, the electronic structure and the physicochemical properties of the resulting intercalation compounds are considered. The ties of the resulting intercalation compounds are considered. The potential of this method of synthesis is compared with that of potential of this method of synthesis is compared with that of traditional solid-state methods for the intercalation of layered traditional solid-state methods for the intercalation of layered crystals. The bibliography includes 192 references crystals. The bibliography includes 192 references. .

The three-dimensional atomic structure of MoS2–organic layered systems is obtained for the first time, providing insight into the surface chemistry of charged MoS2 sheets.

We report a facile, room-temperature assembly of MoS2-based hetero-layered nanocrystals (NCs) containing embedded monolayers of imidazolium (Im), 1-butyl-3-methylimidazolium (BuMeIm), 2-phenylimidazolium, and 2-methylbenzimidazolium molecules. The NCs are readily formed in water solutions by self-organization of the negatively charged, chemically exfoliated 0.6 nm thick MoS2 sheets and corresponding cationic imidazole moieties. As evidenced by transmission electron microscopy, the obtained NCs are anisotropic in shape, with thickness varying in the range 5-20 nm and lateral dimensions of hundreds of nanometers. The NCs exhibit almost turbostratic stacking of the MoS2 sheets, though the local order is preserved in the orientation of the imidazolium molecules with respect to the sulfide sheets. The atomic structure of NCs with BuMeIm molecules was solved from powder X-ray diffraction data assisted by density functional theory calculations. The performed studies evidenced that the MoS2 sheets of the NCs are of the nonconventional 1T-MoS2 (metallically conducting) structure. The sheets' puckered outer surface is formed by the S atoms and the positioning of the BuMeIm molecules follows the sheet nanorelief. According to thermal analysis data, the presence of the BuMeIm cations significantly increases the stability of the 1T-MoS2 modification and raises the temperature for its transition to the conventional 2H-MoS2 (semiconductive) counterpart by ∼70 °C as compared to pure 1T-MoS2 (∼100 °C). The stabilizing interaction energy between inorganic and organic layers was estimated as 21.7 kcal/mol from the calculated electron density distribution. The results suggest a potential for the design of few-layer electronic devices exploiting the charge transport properties of monolayer thin MoS2.

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The product of exfoliation and restacking of MoS2 in acidic conditions is studied in detail using X-ray powder diffraction, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The temperature dependence of powder patterns reveals that the heating of exfoliated-restacked MoS2 is a way to a new nanostructured MoS2-based layered material that remains nanosized even upon heating to 850 °C. Previously this material has been described as 2H-MoS2, but according to the X-ray diffraction (XRD) data, its structure cannot be correctly described by any of the “usual” MoS2 polytypes. A model of the structure of the material describing its XRD patterns and thermal behavior is discussed in detail.