Synthesis of the Elusive Doublewall Nanotubes and Nanocones(Horns) of MoS2 via Focused Solar Ablation

The synthesis of fundamentally small MoS2 nanotubes and nanocones(horns) that have proven elusive in prior studies has been achieved via ablation of a precursor mixture of crystallites of MoS2 + MoO3 by highly concentrated solar radiation. The special far-from-equilibrium conditions achieved in the solar furnace prove conducive to the generation of these singular nanostructures. Extensive electron microscopy and characterization results (transmission electron microscopy (TEM), electron diffraction (ED), X-ray diffraction (XRD), scanning TEM (STEM), and high angle annular dark field (HAADF)) reveal a range of nanoparticle shapes and sizes based on which reaction mechanisms are proposed. Molecular dynamics simulations indicate that the sizable thermal fluctuations intrinsically produced in the high-temperature solar reactor soften the MoS2 nanostructures, yielding corrugated layers that favor nanostructures with only a few layers, in agreement with the experimental observations.