Following the synthesis and characterization of carbon nanotubes by Sumio Iijima in 1991, researchers have been interested in synthesizing nanotubes from other single and multilayered materials besides graphene. As early as 1992, one of our groups (Tenne’s) and, later on, others succeeded using boron nitride and the transition metal dichalcogenide (TMDC) compounds tungsten disulfide and molybdenum disulfide.1 In the past two decades, nanotubes have extended to 2D materials composed of two elements—such as metal chalcogenides, halides, and oxides—and three- or four-element misfit layered compounds.2 Misfit compounds comprise alternating slabs of rock-salt structures, such as lead sulfide, and hexagonal layered compounds, such as tantalum disulfide. Given the many materials that form nanotubes in practice and in computer models, the nanostructures seem to be a genuinely stable phase of 2D materials in the nanoscale range.
A material’s properties change dramatically as its dimensions are reduced. The favorable changes from bulk...
