Utilization of Group V and VI 2H-MX2 Transition Metal Dichalcogenides (M = Mo, W; Nb; X = S, Se Te) in chemical sensors, thermal-optical coatings and structural nanocomposites require direct chemical modification of the chalcogenide basal surface. Defect termination with elemental chalcogenide or organic ligands with terminal chalcogenides are routine, however provide only limited control of functionalization density. Current hybridization strategies rely on extreme reduction processes to drive a transformation from the inert 2H to the reactive 1T phase. Conversion back to the 2H phase though is incomplete, resulting in heterogeneous materials. Here in, we demonstrate an alternative method for direct hybridization of Group VI 2H-MX2 TMDs via alkyl organometallic reagents and Group V 2H-MX2 with Lewis acid-base donor-acceptor chemistry. Using the recently development redox exfoliation method, single to few layer TMDs are stabilized in a range of polar organic solvents that are compatible with organometallic chemistries and various Lewis acid-base donor-acceptor moieties. X-ray Absorption Spectroscopy demonstrate strong chalcogen-ligand interaction while X-ray diffraction of assembled nanolaminates resolve an expanded interlayer gallery consistent with basally conjugated short-chain organics. The functionalized 2H-MX2 TMDs can be transferred to non-polar solvents (THF, CHCl3, CH2Cl2), and show enhanced stability from oxidation and degradation. Finally, the developed chemistries are tolerant to –ene and –yne pendant groups, facilitating post-functionalization modification via thiol-ene click chemistry or UV initiated -ene cross-linking allowing for the development of robust nanocomposites. Modulation of the optical and mechanical properties of NbS2, NbSe2 and MoS2 is demonstrated.

Basal plane functionalization of group V and VI layered transition metal dichalcogenides

2019 Spring National Meeting

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