Ammoniated MS 2 (M = Mo,W) have been synthesized by reacting Li x MS 2 with a saturated solution of ammonium chloride. While, largely neutral NH 3 is present in the interlayer of ammoniated MoS 2 , equal amounts of NH 3 and NH 4 + ions are present in the tungsten analog. The ammoniated MS 2 exfoliate readily in a variety of polar solvents with exfoliation being best in water. Ammoniated WS 2 forms a more stable colloidal dispersion compared to the Mo analog because the ammonium ions do not deintercalate easily from the layers even on exfoliation. The dispersions are comprised of large nanosheets of MS 2 with lateral dimensions in the order of micrometers. The layers could be restacked from the colloidal dispersions by evaporating the solvent. While the colloidal dispersions of ammoniated MoS 2 yield NH 3 -free MoS 2 on restacking, the dispersions of ammoniated WS 2 yield WS 2 intercalated with NH 4 + ions. Co-stacking of MoS 2 and WS 2 nanosheets from a mixture of both the colloidal dispersions results in MoS 2 −WS 2 hybrids in which the MoS 2 and WS 2 nanosheets are randomly stacked. Photoluminescence measurements of MS 2 nanosheets and MoS 2 −WS 2 hybrids indicate phase stability and existence of direct bandgap.

WS2 nanoribbons have been synthesized by chemical unzipping of WS2 nanotubes. Lithium atoms are intercalated in WS2 nanotubes by a solvothermal reaction with n-butyllithium in hexane. The lithiated WS2 nanotubes are then reacted with various solvents--water, ethanol, and long chain thiols. While the tubes break into pieces when treated with water and ethanol, they unzip through longitudinal cutting along the axes to yield nanoribbons when treated with long chain thiols, 1-octanethiol and 1-dodecanethiol. The slow diffusion of the long chain thiols reduces the aggression of the reaction, leading to controlled opening of the tubes.

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Carbon shell encapsulated metal nanoparticles (M@C) are key materials for fuel cell and water electrolysis applications. This review highlights the current challenges and future prospects of M@C electrocatalysts.

Amine intercalated MS2 exfoliate in organic solvents to give large 2D nanosheets.