Onion-like carbon

Kuznetsov VL, Chuvilin AL, Butenko YV et al (1994) Onion-like carbon from ultra-disperse diamond. Chem Phys Lett 222 343-348... 

Kuznetsov V.I. and Butenko Yu.V. (2003) Synthesis and properties of nanostructured carbon materials nano-diamond, onion-like carbon and carbon nanotubes. In Proceedings of NATO Advanced Research Workshop on Nanostructured Materials and Coatings for Biomedical and Sensor Applications , 4-8 August 2002. Eds. Gogotsi Y.G. and Uvarova I.V. V. 102, IOS Press, p. 187-202. 

Qiao ZJ, Li JJ, Zhao NQ, Shi CS et al (2006) Graphitization and microstructure transformation of nanodiamond to onion-like carbon. Scripta Materialia 54(2) 225-229... 

Usually, the vaporization of the entire carbon sample prior to conversion is not required in this type of reaction. It will do if a sufficiently large number of carbon atoms are mobilized and settle at a new equilibrium position. This may be achieved by thermal vibrations at elevated temperatures, but the so-called knock-on effects at particle bombardment or irradiation may serve to the same end. In the sections below, the products of thermal treatment and of various irradiations will be presented starting from different forms of carbon. All these procedures have in common that normally a heterogeneous mixture of products is obtained. Still these may often be prepared in macroscopic amounts, thus presenting the opportunity to study the physical and chemical properties of onion-like carbon materials. 

The stmcture of products from sooting benzene/oxygen flames has also been studied in this context. It turned out that the sooty film precipitating on the cool parts of the apparatus consists of tubular and onion-like carbon species. Still the product obtained is rather inhomogeneous, so for the time being, combustion methods are no effective means of generating carbon onions. 

Altogether the thermal transformation of nanodiamond turned out a suitable method to prepare macroscopic amounts of onion-like carbon. It is true that the products obtained are inhomogeneous to some extent and that the resulting onions show various deficiencies (defects, deviations from spherical shape), but still the heating of diamond in vacuo constitutes the best method to date to generate larger amounts of carbon onions and study in principle their physical and chemical properties. 

Figure 4.27 Formation of onion-like carbon by the so

A wide variety of carbon materials is known for their applicability as a catalyst or support of it. Especially the activated carbons with their large specific surface can be employed. But also carbon nanotubes and, to some degree, the fullerenes may be used to the same end. Besides, carbon onions and onion-like carbons are promising for catalytic applications, too. They feature a considerable specific surface, bear little structural defects (at suitable preparation), and they are stable over a wide range of temperatures. 

Figure 4.43 The dehydrogenation of ethylbenzene may be catalyzed by the addition of onion-like carbon.

Kuznetsov, V.L. and Butenko, Y.V. (2005) Nanodiamond Graphitization and Properties of Onion-like Carbon, in Synthesis, Properties and Applications of Ultrananocrystalline Diamond, NATO Science Series, vol. 192 (eds D.M. Gruen,... 

Thus far, four mechanisms for the formation of concentric shell carbon particles as zero-dimensional carbon allotropes have been proposed. The first mechanism is the formation of a corannulene carbon framework followed by a spiral-shell growth [48], The second mechanism is that the regular concentric arrangements of carbon layers in the onion-like carbon sphere occur through the solidification process of a carbon droplet under ultrafast condensation [49], The third mechanism is due to a solid —> quasi-liquid — solid process that is, reorganization of soot-containing tubular and polyhedral graphitic particles by... 

FIGURE 2.53 Influence of electrode curvature on differential capacitance. R is the radius of an OLC and is infinity for the planar electrodes. (Reprinted with permission from Feng, G., D. E. Jiang, and P. T. Cummings. 2012. Curvature effect on the capacitance of electric double layers at ionic liquid/onion-like carbon interfaces. Journal of Chemical Theory and Computation 8 1058-1063. Copyright 2012 American Chemical Society.)... 

Li, S., K. L. Van Aken, J. K. McDonough, G. Feng, Y. Gogotsi, and P. T. Cummings. 2014. The electrical double layer of dicationic ionic liquids at onion-like carbon surface. Journal of Physical Chemistry C 118 3901-3909. 

Li, S., G. Feng, P. F. Fnlvio et al. 2012. Molecular dynamics simulation study of the capacitive performance of a binary mixture of ionic liquids near an onion-like carbon electrode. Journal of Physical Chemistry Letters 3 2465-2469. 

Pech, D., M. Brunet, H. Durou et al. 2010. Ultrahigh-power micrometre-sized supercapacitors based on onion-like carbon. Nature Nanotechnology 5 651-654. 

Kovalenko, 1., Bucknall, D. G., and Yushin, G. [2010]. Detonation nanodiamond and onion-like-carbon-embedded polyaniline for supercapacitors, y4dv. Funct Mater., 20, pp. 3979-3986. 

Wu G, Dai CS, Wang DL, Li DY, Li N (2010) Nitrogen-doped magnetic onion-like carbon as support for Pt particles in a hybrid cathode catalyst for fuel cells. J Mater Chem 20(15) 3059-3068... 

Wu G, Nelson M, Ma SG, Meng H, Cui GF, Shen PK (2011) Synthesis of nitrogen-doped onion-like carbon and its use in carbon-based CoFe binary non-precious-metal catalysts for oxygen-reduction. Carbon 49(12) 3972-3982... 

NMR spectroscopy of adsorbed xenon for testing the chemical state of the surface of mesoporous carbon materials illustrated by the example of aggregates of diamond and onion-like carbon nanoparticles. 2009 50 26-30. 

Synthesis of Onion-Like Carbon as Alternative Material.286... 

Electromagnetic Shielding in Onion-Like Carbons and Their Composites...296... 

Carbon onions are a member of the family of nanometer-scale graphite-like aU-carbon allotropes, the emergence of which was catalyzed by the Nobel Prize-winning discovery of the first member, the fullerene, by Kroto et al. in 1985. Initially, carbon onions were observed by lijima in 1980, and were brought to popular attention by the experiments of Ugarte in 1992. Structurally, they consist of concentric spherically 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 is a class of material known as onion-like carbons (OLCs), which include polyhedral nanostructures such as ideal nested fullerenes. This material, rather than ideal spherical carbon onions, can be currently produced in macroscopic quantities, and, hence, be used for future applications. 

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