Exfoliation of lamellar materials into their corresponding layers represented a breakthrough, due to the outstanding properties arising from the nanometric thickness confinement. Among the cleavage techniques, liquid-phase exfoliation is now on the rise because it is scalable and leads to easy-to-manipulate colloids. However, all appropriate exfoliating solvents exhibit strong polarity, which restrains a lot the scope of feasible functionalization or processing of the resulting flakes. Here we propose to extend this scope, demonstrating that nanosheets exfoliated in a polar medium can be properly dispersed in a non-polar solvent. To that purpose, we prepared suspensions of molybdenum disulfide flakes in isopropanol/water and developed a phase transfer of the nanosheets to chloroform via precipitation and redispersion/centrifugation sequences, without any assisting surfactant. The colloidal stability of the nanosheets in chloroform was found to be governed by their lateral dimensions and, although lower than in polar media, proved to be high enough to open the way to subsequent functionalization or processing of the flakes in non-polar medium.

Chemical functionalization of low-dimensional nanostructures has evolved as powerful tool to tailor the materials' properties on demand. For two-dimensional transition metal dichalcogenides, functionalization strategies are mostly limited to the metallic 1T-polytype with only few examples showing a successful derivatization of the semiconducting 2H-polytype. Here, we describe that liquid-exfoliated WS 2 undergoes a spontaneous redox reaction with AuCl 3 . We propose that thiol groups at edges and defects sites reduce the AuCl 3 to Au 0 and are in turn oxidized to disulfides. As a result of the reaction, Au nanoparticles nucleate predominantly at edges with tuneable nanoparticle size and density. The drastic changes in nanosheet mass obtained after high loading with Au nanoparticles can be exploited to enrich the dispersions in laterally large, monolayered nanosheets by simple centrifugation. The optical properties (for example photoluminescence) of the monolayers remain pristine, while the electrocatalytic activity towards the hydrogen evolution reaction is significantly improved.

Layered two‐dimensional (2D) inorganic transition‐metal dichalchogenides (TMDs) have attracted great interest as a result of their potential application in optoelectronics, catalysis, and medicine. However, methods to functionalize and process such 2D TMDs remain scarce. We have established a facile route towards functionalized layered MoS2. We found that the reaction of liquid‐exfoliated 2D MoS2, with M(OAc)2 salts (M=Ni, Cu, Zn; OAc=acetate) yielded functionalized MoS2–M(OAc)2 materials. Importantly, this method furnished the 2H‐polytype of MoS2 which is a semiconductor. X‐ray photoelectron spectroscopy (XPS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT–IR), and thermogravimetric analysis (TGA) provide strong evidence for the coordination of MoS2 surface sulfur atoms to the M(OAc)2 salt. Interestingly, functionalization of 2H‐MoS2 allows for its dispersion/processing in more conventional laboratory solvents.