title: Liquid-Phase Exfoliation of MoS2Nanosheets: The Critical Role of Trace Water.
abstract: Sonication-assisted liquid-phase exfoliation of layered materials in suitable organic solvents offers a simple scalable route for the production of 2D nanomaterials. N-methyl-2-pyrrolidone (NMP) is one of the most efficient solvents for liquid-phase exfoliation of a variety of layered solids, including MoS2. We show here that trace water present in NMP is crucial for the stability of MoS2nanosheets in NMP dispersions. In the absence of water, the sheets are fragmented and chemically unstable. Using solution NMR techniques, 2D nuclear Overhauser effect and spin-lattice relaxation measurements, supported by classical molecular dynamics simulations, we are able to establish the role of water molecules in stabilizing the dispersion. We show that water molecules are localized at the Mo-terminated edges of the MoS2sheets, thereby inhibiting chemical erosion of the sheets, and they also exhibit enhanced interactions with the solvent NMP molecules, leading to the stability of the dispersion.
authors.affiliation: Department of Inorganic and Physical Chemistry, Indian Institute of Science , Bangalore 560012, India.
authors.forename: Amit
authors.initials: A
authors.lastname: Gupta
authors.affiliation: Department of Inorganic and Physical Chemistry, Indian Institute of Science , Bangalore 560012, India.
authors.forename: Vaishali
authors.initials: V
authors.lastname: Arunachalam
authors.affiliation: Department of Inorganic and Physical Chemistry, Indian Institute of Science , Bangalore 560012, India.
authors.forename: Sukumaran
authors.initials: S
authors.lastname: Vasudevan
mesh_terms: D004220:Disulfides / Q000737:chemistry*; D019216:Metals, Heavy / Q000737:chemistry*; D008982:Molybdenum / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D004220:Disulfides; D019216:Metals, Heavy; D014867:Water; D008982:Molybdenum; C082964:molybdenum disulfide