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Layered transition metal dichalcogenides contain a number of crystal defects that significantly change their properties and are beneficial or detrimental for a specific application. We have prepared defect-rich multiwalled WS2 nanotubes by reductive sulfidization of W18O49 nanowires that were obtained solvothermally from tungsten chloride in different alcohols. The synthesis of the W18O49 nanowires was monitored, and their morphological characteristics (e.g., length, rigidity, and aspect ratio) are described in detail. The effect of the morphology of the nanowires on the synthesis of WS2 nanotubes was investigated in order to obtain WS2 nanotubes that are highly solvent-dispersible. Dispersions of the WS2 nanotubes in organic solvents are very stable for several days. The nanotubes were easily functionalized with noble metal, metal oxide, and Janus-type metal@metal oxide nanoparticles. The synthesis of nanowires and nanotubes and the immobilization of the nanoparticles were demonstrated by TEM, high-resolution TEM (HRTEM) combined with energy-dispersive X-ray spectroscopy (EDX), electron diffraction (ED), XRD, and Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Closed WS2 nanoboxes were formed by topotactic sulfidization of a WO3/WO3·1/3H2O intergrowth precursor. Automated diffraction tomography was used to elucidate the growth mechanism of these unconventional hollow structures. By partial conversion and structural analysis of the products, each of them representing a snapshot of the reaction at a given point in time, the overall reaction can be broken down into a cascade of individual steps and each of them identified with a basic mechanism. During the initial step of sulfidization WO3·1/3H2O transforms into hexagonal WO3 whose surface allows for the epitaxial induction of WS2. The initially formed platelets of WS2 exhibit a preferred orientation with respect to the nanorod surface. In the final step individual layers of WS2 coalesce to form closed shells. In essence, a cascade of several topotactic reactions leads to epitactic induction and formation of closed rectangular hollow boxes made up from hexagonal layers. [ABSTRACT FROM AUTHOR]