Onion-like Fullerenes Research Articles

Stiffening of double-shelled fullerene molecules under uniaxial strains

Onion-like fullerenes (OLFs) have spherical and tunable shell structures that make them perfect solid lubricants, but their molecular mechanical properties are largely unknown as they are extremely difficult to measure. In this computational study, double-shelled OLFs C60@C180, C80@C180, C60@C240 and C80@C240 are subject to uniaxial elastic strains to obtain their mechanical response. Compressive and tensile elastic moduli are calculated using density functional theory with van der Waals correction. We found that the tensile elastic moduli of the single- and double-shelled fullerenes are always larger than the compressive ones by about 50% to 100%. Inserting C80 into C180 causes an increase in compressive elastic modulus from 96.8 GPa to 178.6 GPa, while inserting C60 into C240 cause much smaller increases. The key factor that determines the stiffening effects is the relative sizes of the inner and outer shells.

Size-dependent melting of onion-like fullerenic carbons: a molecular dynamics and machine learning study

The melting thermodynamic characteristics of 2- to 20-layered onion-like fullerenes (OLF n ) (C60@C240 to C60@···@C6000···@C24000) are comprehensively explored using first-principles-based ReaxFF atomistic simulations and random forest machine learning (RF ML). It is revealed that OLF n shows lower thermal stability than the counterparts of single-walled fullerenes (SWF n ). The melting point of SWF n increases monotonically with increasing size, whereas for OLF n , an unusual size-dependent melting point is observed; OLF n with intermediate size shows the highest melting point. For small OLF n , the melting occurs from the inner to the outer, whereas for large OLF n , it nucleates from the inner to the outer and to intermediate fullerenes. The melting and erosion behaviors of both SWF n and OLF n are mainly characterized by the nucleation of non-hexagons, nanovoids, carbon chains and emission of C2. RF ML model is developed to predict the melting points of both SWF n and OLF n . Moreover, the analysis of the feature importance reveals that the Stone-Wales transformation is a critical pathway in the melting of SWF n and OLF n . This study provides new insights and perspectives into the thermodynamics and pyrolysis chemistry of fullerenic carbons, and also may shed some lights onto the understanding of thermally-induced erosion of carbon-based resources and spacecraft materials.

Onion‐like fullerene as a carrier for the synthesis of platinum catalysts and its application to the electrochemical hydrogenation of soybean oil

In this study, Pt/OLF catalysts were synthesized using onion-like fullerenes (OLF) as carriers and applied as cathode catalysts in solid polymer electrolyte (SPE) electrochemical reactors for the preparation of hydrogenated oils. The results show that OLF is a good carrier, and the specific surface area and accumulated pore area of OLF are increased after oxidation by 264.50% and 256.83%, respectively. The loaded Pt forms uniformly dispersed crystalline particles (14.59 nm) on the OLF, and the crystallization is dominated by 111 crystalline planes. In the hydrogenation process, the Pt/OLF catalyst shows lower trienoate selectivity, lower activation energy (21.36 kJ/mol), and higher catalytic activity than the Pt/C catalyst. In addition, the hydrogenated product prepared with the Pt/OLF catalyst has a lower trans fatty acids (TFA) content than that of Pt/C, and the oil crystallization in the product is more uniform, but no difference in flavor is found for the Pt/C-hydrogenated oil, which is an excellent quality hydrogenated product. Novelty impact statement Preparation of Pt-based catalyst with good catalytic activity using onion-like fullerenes (OLF) as carrier. Application of Pt/OLF catalyst to SPE electrochemical hydrogenation reactor to hydrogenated soybean oil. Prepared a hydrogenated product with low trans fatty acids, uniform crystallinity, and good quality.

Control and Modification of Nanostructured Materials by Electron Beam Irradiation

I have proposed a bottom-up technology utilising irradiation with active beams, such as electrons and ions, to achieve nanostructures with a size of 3–40 nm. This can be used as a nanotechnology that provides the desired structures, materials, and phases at desired positions. Electron beam irradiation of metastable θ-Al2O3, more than 1019 e/cm2s in a transmission electron microscope (TEM), enables the production of oxide-free Al nanoparticles, which can be manipulated to undergo migration, bonding, rotation, revolution, and embedding. The manipulations are facilitated by momentum transfer from electrons to nanoparticles, which takes advantage of the spiral trajectory of the electron beam in the magnetic field of the TEM pole piece. Furthermore, onion-like fullerenes and intercalated structures on amorphous carbon films are induced through catalytic reactions. δ-, θ-Al2O3 ball/wire hybrid nanostructures were obtained in a short time using an electron irradiation flashing mode that switches between 1019 and 1022 e/cm2s. Various α-Al2O3 nanostructures, such as encapsulated nanoballs or nanorods, are also produced. In addition, the preparation or control of Pt, W, and Cu nanoparticles can be achieved by electron beam irradiation with a higher intensity.

Fabrication of onion-like fullerene nanostructure film by electrochemical reduction

Onion-like fullerenes possess distinctive physical and chemical performance, and thus are believed to have great significance in theoretical study and engineering applications. In this exploratory research, we introduced a novel way, namely electrochemical reduction method performed in aqueous solution at room temperature and very low voltages, for preparing a film composed of onion-like fullerene nanostructures. The method was discovered by accident. During the preparation of thick Cr coating by electrodepositing from Cr (III) electrolyte, a layer of black film was found at the interface between the steel substrate and Cr coating. XPS analysis shows that the main element contained in the film is C. The results from Raman spectrum, HRTEM and SAED reveal that the carbonaceous film is composed of the nanostructures roughly having onion-like fullerene unit. This means with significant advantages has the potential to develop into a practical technique for fabricating carbonaceous films or coatings.

Multiwall and bamboo-like carbon nanotubes from the Allende chondrite: A probable source of asymmetry.

This study presents multiwall and bamboo-like carbon nanotubes found in samples from the Allende carbonaceous chondrite using high-resolution transmission electron microscopy (HRTEM). A highly disordered lattice observed in this material suggests the presence of chiral domains in it. Our results also show amorphous and poorly-graphitized carbon, nanodiamonds, and onion-like fullerenes. The presence of multiwall and bamboo-like carbon nanotubes have important implications for hypotheses that explain how a probable source of asymmetry in carbonaceous chondrites might have contributed to the enantiomeric excess in soluble organics under extraterrestrial scenarios. This is the first study proving the existence of carbon nanotubes in carbonaceous chondrites.

Theoretical study of nano onion-like fullerenes C20@C80 on XPS and NEXAFS spectra

ABSTRACTThe X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy of the carbon K-edge for the two nano onion-like fullerenes (NOLFs) C isomers have been in theory performed by density functional theory (DFT) method. We have especially focussed on the structure-spectroscopy relationship by exploring in detail and analyzing systematically the calculated spectra. Both the XPS and NEXAFS spectra show dependence on molecular structures, so these two spectroscopic techniques can be used to identify the two NOLFs C isomers. Meanwhile, the spectral components of each C isomer based on the local environment of carbon atoms have been calculated at the same level. Furthermore, we have tested the feasibility of using the building block (BB) approach to quickly estimate the XPS and NEXAFS spectra in the NOLFs C system. Results show that applying the BB approach is impossible to predict the direct calculated results for the NOLFs C. Additionally, fullerene C(D) as an isomer of C can be distinguished from the two C isomers by the XPS and NEXAFS spectra.

Tribological properties of onion like fullerenes and NiFe2O4 nanocomposites in reciprocating motion

A novel way for a compressor to improve its coefficient of performance and enhance its reliability by employing nano-refrigeration lubricant oil was proposed. Onion like fullerenes (OLFs) and NiFe2O4 nano-composites, modified by Span 80, were dispersed in refrigeration oil KFR22 by solid grinding (SG). Morphologies of NiFe2O4 nano-composites were characterized by using transmission electron microscope (TEM). The tribological properties as a refrigeration lubricants additive were investigated using SRV (II), a multi-functional reciprocating friction and wear tester. The results showed that the friction coefficient was decreased from 0.15 to 0.04.

Quantum transport through single and multilayer icosahedral fullerenes

We use a tight-binding Hamiltonian and Green functions methods to calculate the quantum transmission through single-wall fullerenes and bilayered and trilayered onions of icosahedral symmetry attached to metallic leads. The electronic structure of the onion-like fullerenes takes into account the curvature and finite size of the fullerenes layers as well as the strength of the intershell interactions depending on to the number of interacting atom pairs belonging to adjacent shells. Misalignment of the symmetry axes of the concentric iscosahedral shells produces breaking of the level degeneracies of the individual shells, giving rise some narrow quasi-continuum bands instead of the localized discrete peaks of the individual fullerenes. As a result, the transmission function for non symmetrical onions is rapidly varying functions of the Fermi energy. Furthermore, we found that most of the features of the transmission through the onions are due to the electronic structure of the outer shell with additional Fano-like antiresonances arising from coupling with or between the inner shells.

Low Temperature Synthesis of Nano-Carbon Materials Using a Water-Soluble Catalyst Support by Chemical Vapor Deposition

Nano-carbon materials were synthesized by catalytic decomposition of acetylene at low temperature 400 °C and 420 °C using iron supported on sodium chloride as catalyst. The samples were examined by X-ray diffraction, scanning electron microscopy and high resolution transmission electron microscopy. The results show that nano onion-like fullerenes encapsulating Fe cores with diameters in the range 20-50 nm were obtained when the reaction temperature was 400 °C and there were no carbon nanotubes in the product. These onion-like fullerenes are composed of concentric graphene layers with an interlayer distance of 0.348 nm between the layers. When the reaction temperature was 420 °C, carbon nanotubes with a structure of rope and low graphitization degree were obtained.

Low Temperature Synthesis of Onion-Like Fullerenes Using Aluminum Hydroxide Supported Iron Catalyst

Synthesis of onion-like fullerenes was carried out by chemical vapor deposition in a tubular furnace using iron catalyst supported on aluminum hydroxide at 400°C, 460°C, 600°C, 700°C, 800°C, 900°C and 1000°C, respectively, in the presence of argon as carrier gas and acetylene as the carbon source. The samples synthesized were characterized by high-resolution transmission electron microscopy, and the effects of temperature on the morphologies of the samples were investigated. The results show that the onion-like fullerenes prepared at the low temperature 400°C had the highest purity and good quality.

Low Temperature Large Scale CVD Synthesis of Nano Onion-Like Fullerenes

Synthesis reactions were carried out by chemical vapor deposition using iron catalyst supported on aluminum hydroxide at 400 °C and 420 °C, in the presence of argon as carrier gas and acetylene as carbon source. The aluminum hydroxide support was separated by refluxing the samples in 40% NaOH solution for 2 h and 36% HCl solution for 24 h, respectively. The samples were characterized by field-emission scanning electron microscopy, energy dispersive spectroscopy, high-resolution transmission electron microscopy and X-ray diffraction. The results show that carbon nanotubes were the main products at 420 °C, while large scale high purity nano onion-like fullerenes encapsulating Fe3C, with almost uniform sizes ranging from 10-50 nm, were obtained at the low temperature of 400 °C.

Synthesis of Onion-Like Fullerenes by Arc Discharge in Non-Toxic Organic Liquid

The effect of different organic media on synthesis of carbon nanomaterials in this study was discussed, Onion-like Fullerenes (OLFs) and Multi-walled carbon nanotubes can be synthsized by arc discharge in dextrin with graphite can be used as electrodes. Field-emission scanning electron microscopy (FESEM) and High resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques were used to characterize morphologies and structures of the products. Results show that OLFs and Multi-walled carbon nanotubes with large amount were observed in the deposit formed on the surface of cathode. The arc discharge in polyethylene glycol solution gave but large quantity of carbon nanotubes rather than OLFs.

Synthesis of Nano Onion-Like Fullerenes Using Iron Supported on Sodium Chloride as Catalyst by Decomposing Acetylene

Catalytic decomposition of acetylene was carried out at 400 °C using iron supported on sodium chloride as catalyst and the product was heat-treated at 650 °C under an argon atmosphere for 2 h directly. The sample was examined by scanning electron microscopy, high resolution transmission electron microscopy and X-ray diffraction. The results show that nano onion-like fullerenes encapsulating Fe cores with diameters in the range 20-50 nm were obtained.

Three-Stage Transformation Pathway from Nanodiamonds to Fullerenes

The dynamics of structure evolution of nanodiamonds ranging from 22 to 318 atoms of various shapes is studied by density functional tight-binding molecular dynamics. The spherical and cubic nanodiamonds can be transformed into fullerene-like structures upon heating. A number of the transformed fullerenes consist of pentagons and hexagons only. Others contain squares, heptagons, and octagons. One simulated fullerene is an isomer of C(60). The temperature of the transformation depends on the size, shape, and orientation of initial cluster. To be transformed into onion-like fullerenes, the spherical nanodiamonds should have 200 atoms or more, while the cubic ones require 302 atoms or more. The time-resolved energy profiles of all the transformations clearly reveal three-stage transformation character. During the first stage, the energy reduces quickly due to converting sp(3) carbon with dangling bond at the surface into sp(2) one, and the formation of partial sp(2) envelope wrapping the cluster. For the second stage, energy decreases slowly. The remaining interior carbon atoms come to the surface through the hole in the sp(2) envelope, and similar amount of sp(3) and sp(2) atoms coexist. The third stage involves the closure of holes, accompanied by the detachment of C(2) molecules and carbon chains from the edges. The energy decreases relatively fast in this stage. The proposed three-stage transformation pathway holds for all the simulations performed in this work, including those with the instant heating.

Structural characteristics of nanocrystalline copper after carbon ion implantation

A gradient structure was produced in a pure copper plate by means of surface mechanical attrition treatment (SMAT). The microstructure of the surface layer was reduced to nanoscale and the grain size increased gradually along the depth of the treated sample. In situ transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) observation was performed on the nanocrystalline copper after implantation of carbon. Carbon atoms first precipitated along the edges of the copper substrate or at the surface, then formed amorphous carbon layers. Subsequently, onion-like fullerenes were formed under electron-beam irradiation. The effects of ion implantation, electron beam irradiation, nanostructure of the substrate and interaction of C and Cu atoms on the formation of the onion-like fullerenes are discussed.

Fluidity of onion-like fullerenes in mice after a functionalization modification

Water-soluble onion-like fullerene(OLF)derivatives were prepared by chemical bonding of L-cysteine,an important amino acid in organisms,to OLFs.The L-cysteine OLFs were characterized by SEM,XRD,IR,TGA and XPS.Results showed that hydrophilic groups added to the surface of OLFs such as-OH and-NH3 made L-cysteine OLFs good water-soluble derivatives.Experiments in mice demonstrated that the water-soluble fullerene derivatives were well distributed in the histolytic organism because of their excellent solubility and fluidity in humoral liquid.

Studies on the Growth Mechanism of Onion-Like Fullerenes by Arc Discharge in Liquid Benzene

The growth mechanism of Onion-like fullerenes (OLFs) synthesized by arc discharge in liquid benzene was discussed. HRTEM was employed to characterize the morphologies and microstructures of the products. Results showed that the typical OLFs were highly crystallized with uniform diameter of 10-30nm. The growth of OLFs depended on the appropriate temperature gradient and quenching zone provided by the bubbles. The aromatic debris could act as graphite fragments composed of hexagonal carbon rings. The reducing of dangling bonds on the edges of graphite fragments would lower the energy of the system, resulting in formation of a close-caged structure at suitable temperature gradient by the auto-curling of graphite fragments. Based on the impact of the innermost core shape, such as C60 shape, quasi-spherical or polyhedral hollow concentric OLFs was formed. Adding ferrocene, ferrocene directly influenced the morphology and yield of OLFs.

Ferromagnetic Property and Synthesis of Onion-Like Fullerenes by Chemical Vapor Deposition Using Fe and Co Catalysts Supported on NaCl

Metal-encapsulating onion-like fullerenes (M@OLFs) were synthesized by CVD at relatively low temperature (420C∘) using Fe and Co nanoparticles impregnated into NaCl as catalyst. The morphology and structure of the products were characterized by field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. The results show that Fe@OLFs and Co@OLFs with stacked graphitic fragments were prepared using Fe/NaCl or Co/NaCl as catalysts; after Co@OLFs were immersed in concentrated HCl for 48 hours, Co nanoparticles encapsulated by carbon shells were not removed, meaning that carbon shells can protect the encapsulated Co cores against environmental degradation. The coercivity value (750.23 Oe) of Co@OLFs showed an obvious magnetic property.

Synthesis of nano onion-like fullerenes by chemical vapor deposition using an iron catalyst supported on sodium chloride

Nano-carbon materials were synthesized by the catalytic decomposition of acetylene at 420 °C using iron supported on sodium chloride as catalyst. The catalysts contain about 0.3, 1.6, 3.3, and 5.2 wt% iron. The samples were examined by scanning and transmission electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. The results show that nano onion-like fullerenes (NOLFs) surrounding an Fe3C core were obtained using the catalyst containing 0.3 wt% iron. These had a structure of stacked graphitic fragments, with diameters in the range 15–50 nm. When the product was further heat treated under vacuum at 1,100 °C, NOLFs with a clear concentric graphitic layer structure were obtained. The growth mechanism of NOLFs encapsulating metallic cores is suggested to be in accordance with a vapor–solid growth model.