Reactivity Differences between Carbon Nano Onions (CNOs) Prepared by Different Methods

• Published in: Chemistry, an Asian journal an Asian journal, 2007-05, Vol.2 (5), p.625-633
• Main Authors: Palkar, Amit, Melin, Frederic, Cardona, Claudia M., Elliott, Bevan, Naskar, Amit K., Edie, Danny D., Kumbhar, Amar, Echegoyen, Luis
• Format: Article
• Language: English
• Subjects: annealing; fullerenes; nano onions; nanodiamonds; nanostructures
• ISSN: 1861-4728; 1861-471X
• DOI: 10.1002/asia.200600426

The carbon nanoparticles obtained from either arcing of graphite under water or thermal annealing of nanodiamonds are commonly called carbon nano onions (CNOs), or spherical graphite, as they are made of concentric fullerene cages separated by the same distance as the shells of graphite. A more careful analysis reveals some dramatic differences between the particles obtained by these two synthetic methods. Physicochemical methods indicate that the CNOs obtained from nanodiamonds (N‐CNOs) are smaller and contain more defects than the CNOs obtained from arcing (A‐CNOs). These properties explain the enhanced reactivity of the N‐CNOs in cycloaddition and oxidation reactions, as well as in reactions involving radicals. Given the easier functionalization of the N‐CNOs, they are the most obvious choice for studying the potential applications of these multi‐shelled fullerenes. Size does matter: Carbon nano onions obtained from annealing of nanodiamonds (left) and from arcing of graphite under water (right) display dramatic differences in properties and chemical reactivity. The former are smaller and more defective, and consequently more reactive than the latter.