ABSTRACT
Carbon onions are a member of the family of nanometer-scale graphite-like all-carbon allotropes, the emergence of which was catalyzed by the Nobel Prize-winning discovery of the rst member, the fullerene, by Kroto and coworkers in 1985 (Kroto et al. 1985). Initially observed by Iijima (1980) and brought to popular attention by the experiments of Ugarte (1992), carbon onions consist of concentric spherical closed carbon shells and receive their name from the close resemblance between their nanoscale structure and the more familiar concentric layered structure of an onion. Closely related to carbon onions are a class of materials known as “onion-like carbons (OLCs),” which include polyhedral nanostructures such as ideal nested fullerenes and it is this material, rather than ideal spherical carbon onions, that can currently be produced in macroscopic quantity and hence be used for future applications.
