Exotic Core-Shell Nanotubes Synthetized via van der Waals Epitaxy

Inorganic nanotubes from transition metal dichalcogenides (TMDCs) contain various nanomaterials. Mainly studied are WS₂ or MoS₂ nanotubes. Such materials are usually synthesized via high-temperature synthesis, transport, or solvothermal reactions. Yet some members of TMDCs were not successfully obtained in nanotubular form due to collapsing of the structure or other limitations. Van der Waals epitaxy is a key synthetic strategy for obtaining various 2D heterostructures, including various transition metal dichalcogenides. Thanks to weak interactions between layers, possible lattice strain between divergent compounds is fully relaxed. In other words, heterolayers influence each other physically, mainly as layer alignment, orientations, or different interlayer distances. In the presented methodology, WS₂ nanotubes were mixed with precursor metal oxide and subsequently tellurized, selenized, or sulfidized, reaching multiwall WS₂@MX₂ nanotubes. In such a way, WTe₂, MoTe₂, ReSe_2, and ReS₂ were deposited on the WS₂ nanotube target. Presented heterogeneous nanostructures were analyzed mainly by transmission electron microscopy and 4D scanning transmission electron microscopy, revealing their complex structures. The prepared nanotubes promise modified electronic properties due to the nanotubular character and also thanks to the 1T'/2H TMDCs junctions.