Nanoparticles of layered compounds with hollow cage structures (inorganic fullerene-like structures)

Using the paradigm of carbon fullerenes, it is shown that nanoparticles of inorganic compounds with a layered structure, like MoS2, are unstable against bending and form hollow closed clusters, designated inorganic fullerene-like structures (IF). The analogy can be extended to similar nanostructures, like nanotubes (NT), nested fullerenes, fullerenes with negative curvature (Schwartzites), etc. Various synthetic routes are described to obtain isolated phases of IF. Pentagons and heptagons are expected to play a primordial role in the folding of these nanostructures but no direct evidence for their presence or their detailed structure exists so far. Depending on the structure of the unit cell of the layered compound, apexes of a different topology, like triangles or rectangles, are believed to be stable elements in IF. Applications of such nanoparticles as solid lubricants in mixtures with lubricating fluids are described.