Formation and interlayer decoupling of colloidal MoSe₂ nanoflowers

We report the colloidal synthesis of substrate-free MoSe₂ nanostructures with a uniform flower-like morphology and tunable average diameters that range from approximately 50-250 nm. The MoSe₂ nanoflowers contain a large population of highly crystalline few-layer nanosheets that protrude from a central core. Aliquot studies and control experiments indicate that the nanoflowers are generated through a two-step process that involves the formation of a core in the early stages of the reaction followed by outward nanosheet growth that can be controlled based on the concentrations of reagents. The effects of laser-induced local heating, bulk-scale heating using a temperature stage, and nanostructuring on the ability to trigger and tune interlayer decoupling were also investigated. Notably, laser-induced local heating results in dynamic and reversible interlayer decoupling. Such capabilities provide a pathway for achieving quasi-two-dimensional behavior in three-dimensionally structured and colloidally synthesized transition metal dichalcogenide nanostructures.