Carbon nano-onions: Unique carbon nanostructures with fascinating properties and their potential applications

Carbon Nano‐Onions: A Review of Recent Progress in Synthesis and Applications

“…CNs with diameters from 8 to 15 nm were observed . Since then, many studies have been published regarding the synthesis of CNOs with different sizes or shapes ,. The main synthetic method has been thermal annealing of ultradispersed NDs .…”

“…Non‐covalent functionalization is mainly based on the preparation of composites containing CNs and polymers or inorganic nanoparticles. CNOs may be incorporated into composites in two ways: (i) earlier functionalized CNOs can act as active sites for polymerization of monomers (the individual components connected via covalent bonding) or as active sites for the nucleation of inorganic components, or (ii) the long polymer chains can be wrapped on the CNO surface by non‐covalent interactions (e. g., adsorption) . Several polymerizations of different monomers, such as aniline, styrene or pyrrole, have been reported ,,.…”

“…They also show interesting electrochemical performances, such as a broad application temperature range from −50 to 100 °C, a wide range of potentials (above 3.7 volts), and high charge/discharge rates (above 200 V s −1 ) ,,. Unfortunately, they have low specific capacitance and low energy density analogous to other CNs ,. To overcome these problems, the combination of CNOs with different types of electroactive materials, which may accumulate energy based on fast and reversible redox reactions, has been performed .…”

Existence of a system of discrete volume-localized quantum levels for charged fullerenes

“…Following the first observation [38] of spherical multi-layered structures, the concept of "carbon onion" was coined in 1992 when the formation of the onion-like spherical particles was demonstrated by heating of nanotubes with an electron beam [39][40][41]. Since then the physical and chemical characteristics of carbon onions was analyzed in numerous theoretical and experimental studies [42][43][44][45]; see the reviews [46][47][48][49][50][51][52][53][54] for the further information on the production, geometrical, physical and chemical properties, and applications of onion-like carbon structures.…”

Evaluation of the Covalent Functionalization of Carbon Nano-Onions with Pyrene Moieties for Supercapacitor Applications

“…In this regard, the capacitive power of an SC is largely associated with an optimal electrode/electrolyte interface, where changes in morphology (rugosity, porosity, channels, etc.) are due to intermolecular forces and/or intra-interclusters, which play a major role [26][27][28][29][30].…”