Inorganic Nanotubes and Fullerene-Like Nanoparticles from Layered (2D) Compounds

Soon after carbon nanotubes were discovered by Iijima (Nature, 1991), we proposed (Nature, 1992) that inorganic layered compounds, like WS₂, are unstable in the planar form in the nanorange. Under proper chemical conditions, this inherent instability leads to folding of the layers and formation of hollow closed-cage structures, that is, nanotubes (INT) and fullerene-like (IF) nanoparticles. Given the elastic energy of the bending, formation of these closed-cage nanostructures is pending on providing enough energy, that is, high temperature reactions. In the following years, we and others have prepared IF/INT from numerous layered compounds and studied their properties. Numerous ab initio studies were also dedicated to the study of nanotubes from different layered compounds. Recent developments in this field will be described, including the study of nanotubes from “misfit” compounds; doping of the IF/INT; ultrahigh temperature synthesis of IF/INT; their optical and electrical properties, and so on. The mechanical properties of individual nanotubes were studied experimentally and using ab initio calculations. Studying in detail the growth-mechanism of IF/INT of several compounds, mostly WS₂ and MoS₂ we were able to scale-up their synthesis to mass production. Several applications for these IF/INT, especially as superior solid lubricants and for reinforcing polymer nanocomposites, were put forward. The successful commercialization of products based on these ideas will be briefly described.