title: Redox Exfoliation of Layered Transition Metal Dichalcogenides.
abstract: Transition metal dichalcogenides (TMDs) have attracted considerable attention in a diverse array of applications due to the breadth of possible property suites relative to other low-dimensional nanomaterials (e.g., graphene, aluminosilicates). Here, we demonstrate an alternative methodology for the exfoliation of bulk crystallites of group V-VII layered TMDs under quiescent, benchtop conditions using mild redox chemistry. Anionic polyoxometalate species generated from edge sites adsorb to the TMD surface and create Coulombic repulsion that drives layer separation without the use of shear forces. This method is generalizable (MS2, MSe2, and MTe2) and effective in preparing high-concentration (>1 mg/mL) dispersions with narrow layer thickness distributions more rapidly and with safer reagents than alternative solution-based approaches. Finally, exfoliation of these TMDs is demonstrated in a range of solvent systems that were previously inaccessible due to large surface energy differences. These characteristics could be beneficial in the preparation of high-quality films and monoliths.
authors.affiliation: Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB , Ohio 45433-7702, United States.
authors.forename: Ali
authors.initials: A
authors.lastname: Jawaid
authors.affiliation: Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB , Ohio 45433-7702, United States.
authors.forename: Justin
authors.initials: J
authors.lastname: Che
authors.affiliation: Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB , Ohio 45433-7702, United States.
authors.forename: Lawrence F
authors.initials: LF
authors.lastname: Drummy
authors.affiliation: Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB , Ohio 45433-7702, United States.
authors.forename: John
authors.initials: J
authors.lastname: Bultman
authors.affiliation: Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB , Ohio 45433-7702, United States.
authors.forename: Adam
authors.initials: A
authors.lastname: Waite
authors.affiliation: Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB , Ohio 45433-7702, United States.
authors.forename: Ming-Siao
authors.initials: MS
authors.lastname: Hsiao
authors.affiliation: Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB , Ohio 45433-7702, United States.
authors.forename: Richard A
authors.identifier: 0000-0003-4589-3423
authors.initials: RA
authors.lastname: Vaia
keywords: MoS2; liquid-phase exfoliation; redox exfoliation; surface oxidation; surface reactivity; transition metal dichalcogenides