Introductory Chapter: Carbon Nanotubes

As a family of rather new nanomaterials, carbon nanotubes (CNTs) are emerging since about two decades. However, their origin dates back almost 70 years ago, when they were observed and described in 1952 for the first time by Radushkevich and Lukyanovich; in 1976, Oberlin and colleagues described the microscopic observation of singleor double-walled carbon nanotubes. In 1991, Iijima demonstrated for the first time a process for preparation of multi-walled carbon nanotubes (MWNTs); this discovery occurred rather fortuitously during testing a new method for arc evaporation to fabricate C60 carbon molecules. Soon later, two seminal studies by the groups of Iijima and Bethune provided mechanistic descriptions of the growth process involved in the formation of single-walled carbon nanotubes [1]. Structurally, such single-walled carbon nanotubes (SWNT) can be conceived as one atom-thick sheets of graphite (“graphene”), which are rolled up (wrapped) to form tubes, as illustrated in Figure 1. Since their discovery in 1991, CNTs have experienced considerable investigative efforts, especially regarding potential smart applications. Those structures first reported in 1991 were MWNTs with a broad range of dimensions. These were basically distant relatives of highly defective carbon nanofibers grown via catalytic chemical vapor deposition. Real molecular nanotubes sensu stricto only came up when they were by chance detected while a catalyst (Fe and Co) material was inserted in the anode during electric-arc discharge synthesis. For the first time, it became possible to synthesize molecular fibers exclusively based on carbon; one can imagine that the excitement was tremendous, since many physical properties of such a fiber had already been theoretically predicted [6].