Nanotubes and fullerene-like nanoparticles from layered transition metal dichalcogenides: Why do they form and what is their significance?

One-dimensional (1D) analogues of two-dimensional (2D) layered materials, especially nanotubes exhibit unique properties, which are distinct from the 2D flakes. The nanotubes and fullerene-like nanoparticles from layered transition metal dichalcogenides (TMDs) are one of the prime foci of this field in the last 30 years. In this concise review, we present the advancement made in the TMDs nanotubes and fullerene-like nanoparticles over the last few years. The synthesis and structure of TMDs nanotubes such as WS₂/MoS₂ are briefly described. The mechanical properties of single WS₂ nanotubes were examined by in-situ electron microscopy techniques and are briefly discussed. Their reinforcement effects in polymer composites are also presented, as well as their superior tribological behavior. The unique optoelectronic properties of WS₂ (MoS₂) nanotubes are presented. Thus, the bulk photovoltaic effect and superconductivity exhibited by WS₂ nanotubes, which are a manifestation of their 1D structure and low symmetry, are revisited briefly. The strong light-matter interaction of nanotubes resulting in polariton quasiparticles and their evolution as a function of nanotube diameter are explained. Last but not least, a new family of misfit layered nanotubes and their exceptional physical properties are briefly touched upon.