Nanomachines & Nanomanipulation Inorganic Nanotubes and Fullerene-like Nanoparticles
Transition metal chalcogenides like MoS2 or WS2 are quasi-two dimensional (2D) compounds. Atoms within a layer are bound by strong covalent forces, while individual layers are held together by van der Waals (vdW) interactions. Similar to carbon, transitional metal chalcogenides also form close caged structures known as inorganic fullerenes (IF) and nanotubes (INTs). Insights into the type and structure of nanotubes, the formation of nanotube caps and the curvature of nanotubes were limited before the advent of aberration-corrected microscopes. Aberration corrected electron microscopy for the study of INTs, especially those of the transition metal chalcogenides is a very recent area of exploration. The elucidation of structure and chirality is essential to the understanding of how nanotubes can have suitable electronic, mechanical, catalytic and other related properties. This thereby can help the preferential and improved synthesis of nanotubes suited for specific applications. Recently aberration corrected STEM has been able to elucidate some important features and aspects of MoS2 nanotubes. Details involving the nature of the nanotubes, as well as the structure and bonding of the Mo-S in the nanotubes have been investigated, and the results have revealed various interesting aspects for the first time. It is hoped that such studies on this family of compounds will enable great interest and subsequent investigations on unraveling some of the hitherto unknown facts about nanotubes in the light of the new advanced microscopic techniques.