Fullerene-like Carbon Research Articles

Structure, mechanical, and frictional properties of hydrogenated fullerene-like amorphous carbon film prepared by direct current plasma enhanced chemical vapor deposition

In this study, fullerene like carbon (FL-C) is introduced in hydrogenated amorphous carbon (a-C:H) film by employing a direct current plasma enhanced chemical vapor deposition. The film has a low friction and wear, such as 0.011 and 2.3 × 10−9mm3/N m in the N2, and 0.014 and 8.4 × 10−8mm3/N m in the humid air, and high hardness and elasticity (25.8 GPa and 83.1%), to make further engineering applications in practice. It has several nanometers ordered domains consisting of less frequently cross-linked graphitic sheet stacks. We provide new evidences for understanding the reported Raman fit model involving four vibrational frequencies from five, six, and seven C-atom rings of FL-C structures, and discuss the structure evolution before or after friction according to the change in the 1200 cm−1 Raman band intensity caused by five- and seven-carbon rings. Friction inevitably facilitates the transformation of carbon into FL-C nanostructures, namely, the ultra low friction comes from both such structures within the carbon film and the sliding induced at friction interface.

Silicon and aluminum doping effects on the microstructure and properties of polymeric amorphous carbon films

Polymeric amorphous carbon films were prepared by radio frequency (R.F. 13.56MHz) magnetron sputtering deposition. The microstructure evolution of the deposited polymeric films induced by silicon (Si) and aluminum(Al) doping were scrutinized through infrared spectroscopy, multi-wavelength Raman spectroscopy, scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The comparative results show that Si doping can enhance polymerization and Al doping results in an increase in the ordered carbon clusters. Si and Al co-doping into polymeric films leads to the formation of an unusual dual nanostructure consisting of cross-linked polymer-like hydrocarbon chains and fullerene-like carbon clusters. The super-high elasticity and super-low friction coefficients (<0.002) under a high vacuum were obtained through Si and Al co-doping into the films. Unconventionally, the co-doped polymeric films exhibited a superior wear resistance even though they were very soft. The relationship between the microstructure and properties of the polymeric amorphous carbon films with different elements doping are also discussed in detail.

Controllable preparation of fluorine-containing fullerene-like carbon film

Fluorine-containing fullerene-like carbon (F-FLC) films were prepared by high frequency unipolar pulse plasma-enhanced chemical vapor deposition. The microstructures, mechanical properties as well as the tribological properties of the films were investigated. The results indicate that fullerene-like microstructures appear in amorphous carbon matrix and increase greatly with the increase of bias voltage from −600 to −1600V. And the fluorine contents in F-FLC films also show a minor rise. In addition, the hardness enhances with the bias voltage and the outstanding elastic recovery maintains because of the formation of fullerene-like microstructures in the F-FLC films. Undoubtedly, the F-FLC film deposited under high bias voltage owns a superiorly low friction, which combines the merits of fluorinated carbon film and fullerene-like carbon film. Moreover, the film also shows a remarkable wear resistance, which is mainly attributed to the excellent mechanical properties. This study provides new insights for us to prepare fluorine-containing FLC films with good mechanical and tribological properties.

Review: carbon onions for electrochemical energy storage

Carbon onions are a relatively new member of the carbon nanomaterials family. They consist of multiple concentric fullerene-like carbon shells which are highly defective and disordered.

The formation of the smallest fullerene-like carbon cages on metal surfaces.

The nucleation and growth of carbon on catalytically active metal surfaces is one of the most important techniques to produce nanomaterials such as graphene or nanotubes. Here it is shown by in situ electron microscopy that fullerene-like spherical clusters with diameters down to 0.4 nm and thus much smaller than C60 grow in a polymerized state on Co, Fe, or Ru surfaces. The cages appear on the surface of metallic islands in contact with graphene under heating to at least 650 °C and successively cooling to less than 500 °C. The formation of the small cages is explained by the segregation of carbon on a supersaturated metal, driven by kinetics. First principles energy calculations show that the clusters polymerize and can be attached to defects in graphene. Under compression, the polymerized cages appear in a crystalline structure.

Fullerene-like carbon nanostructures with tetrahedral and octahedral symmetries

The problem of constructing the 3D models of tetrahedral and octahedral fullerene-like carbon nanostructures was solved with the aid of an algorithm developed for the mapping of atoms in a flat carbon layer onto the surface of a polyhedron.

Nitrogen-doped carbon shell structure derived from natural leaves as a potential catalyst for oxygen reduction reaction

Implementation of non-precious electrocatalysts towards oxygen reduction reaction (ORR) falls in the central focus on fulfilling cost-affordable and high-performance fuel cells and metal/air batteries. Recent first-principles spin-polarized DFT calculations simulated the electrocatalytic ORR reaction process on N-doped C60 fullerene (N-C60) and found that O2 can be chemisorbed and reduced on N-C60, indicating that N-C60 is a potential cathode catalyst for hydrogen fuel cells. In this work, a novel waste-to-resource strategy to convert fallen ginkgo leaves into this new kind of ORR electrocatalyst, nitrogen-doped fullerene-like carbon shell (NDCS), is presented. N is derived from fallen ginkgo leaves, where 10.9–15.5wt% proteins are present. The obtained NDCS possesses 100% catalysis selectivity towards four-electron pathway, and its ORR activities outperform most of the other existing carbon-based catalysts. It also shows significantly improved tolerance against methanol and enhanced long-term stability, compared with the commercial platinum-loaded carbon catalyst. Thus it is experimentally demonstrated that the NDCS is a promising future ORR catalyst, which is well consistent with the quantum mechanics calculations. Additionally, the NDCS presents a high reversible capacity (750mAhg−1 at 0.02A/g) in Li-ion batteries. Since fallen ginkgo leaves are readily available, our study represents an exciting direction for sustainable and low-cost energy conversion and storage materials.

Ultralow friction regime from the in situ production of a richer fullerene-like nanostructured carbon in sliding contact

We provide definitive experimental evidences, and show that the richer sp2-bonded carbon atoms compared to the starting FL-C:H film evolve towards richer FL structures.

Nanotribological performance of fullerene-like carbon nitride films

a b s t r a c t Fullerene-like carbon nitride films exhibit high elastic modulus and low friction coefficient. In this study, thin CNx films were deposited on silicon substrate by DC magnetron sputtering and the tribological behavior at nanoscale was evaluated using an atomic force microscope. Results show that CNx films with fullerene-like structure have a friction coefficient (CoF ∼ 0.009-0.022) that is lower than amorphous CNx films (CoF ∼ 0.028-0.032). Analysis of specimens characterized by X-ray photoelectron spectroscopy shows that films with fullerene-like structure have a higher number of sp

Understanding the ultra-low friction behavior of hydrogenated fullerene-like carbon films grown with different flow rates of hydrogen gas

Fullerene-like hydrogenated carbon (FL-C:H) films that exhibit ultra-low friction and wear in humid conditions have been the subject of extensive researches, but the structure–performance relationship such as the evolution of FL structures under friction is not well understood. We have prepared FL-C:H films with different FL content, and have addressed a detailed investigation on the relationship. It is found that with the increase in FL content, the friction and wear of FL-C:H films can reach as low as 0.011 and 1.48×10−8mm3/Nm, respectively. Examination of the corresponding wear tracks by Raman spectroscopy reveals that not graphitization but friction-induced promotion of FL structures causes the ultra-low friction and wear of FL-C:H films. We therefore claim that FL structures are in close positive relations with the excellent tribological performance of FL-C:H films.

Filtered pulsed cathodic arc deposition of fullerene-like carbon and carbon nitride films

Carbon and carbon nitride films (CNx, 0 ≤ x ≤ 0.26) were deposited by filtered pulsed cathodic arc and were investigated using transmission electron microscopy and X-ray photoelectron spectroscopy. A “fullerene-like” (FL) structure of ordered graphitic planes, similar to that of magnetron sputtered FL-CNx films, was observed in films deposited at 175 °C and above, with N2 pressures of 0 and 0.5 mTorr. Higher substrate temperatures and significant nitrogen incorporation are required to produce similar FL structure by sputtering, which may, at least in part, be explained by the high ion charge states and ion energies characteristic of arc deposition. A gradual transition from majority sp3-hybridized films to sp2 films was observed with increasing substrate temperature. High elastic recovery, an attractive characteristic mechanical property of FL-CNx films, is evident in arc-deposited films both with and without nitrogen content, and both with and without FL structure.

Onion-like carbon in impact diamonds from the Popigai astrobleme

Phase composition and nanostructure of layered and irregular massive impact diamond grains from the Popigai astrobleme have been investigated by Raman spectroscopy and high-resolution electron microscopy and the conditions of phase transformations are discussed. Several coexisting carbon phases forming tight aggregates have been found, including cubic and hexagonal diamond polymorphs, graphite, amorphous carbon, fullerene-like/onion-like carbon. The latter is described within impact diamonds for the first time. It is proposed that the formation of onion-like carbon, in both layered and massive impact diamond grains, is connected with high-pressure graphite transformation or post-pressure stress cooling which causes the partial back transformation of diamond nanocrystallites to sp2 carbon. However, a possible relict origin of the fullerene-like carbon from the impacted initial sedimentary rocks with fullerenes and fullerene-like substances, like shungite or coal, can not be excluded. The difference between micro- and nanostructures of layered and irregular massive impact grains is presented.

Computer models of icosahedral carbon nanostructures (shungite)

A universal algorithm for the generation of three-dimensional models of icosahedral fullerene-like carbon nanostructures has been developed. Coordinates of atoms on their surface are calculated and three-dimensional models of fulleroids – nested icosahedra – are built. A flat model consisting of five graphite layers of varying diameters is computed in an attempt to explain the nature of the diffraction maximum (d≃ 6.81 Å, 2θ ≃ 13°) in shungite carbon by the existence of edge effects, carbon atoms or small fragments of layers in the interlayer space, or dislocation rings.

Hydrophobic, mechanical, and tribological properties of fluorine incorporated hydrogenated fullerene-like carbon films

Abstract Fluorine-incorporated hydrogenated fullerene-like nanostructure amorphous carbon films (F-FLC) were synthesized by employing the direct current plasma enhanced chemical vapor deposition (dc-PECVD) technique using a mixture of methane (CH4), tetra-fluoromethane (CF4), and hydrogen (H2) as the working gases. The effect of the fluorine content on the bonding structure, surface roughness, hydrophobic, mechanical, and tribological properties of the films was systematically investigated using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Raman analysis, atomic force microscope (AFM), contact angle goniometer, nano-indenter, and reciprocating ball-on-disc tester, respectively. The fluorine content in the films increased from 0 to 2.1 at.% as the CF4 gas flow ratio increased from 0 to 3 sccm, and incorporated fluorine atoms existed in the form of C-F X (X = 1, 2, 3) bonds in the film. The fullerene nanostructure embedded in the hydrogenated amorphous carbon films was confirmed by Raman analysis. The water contact angle was significantly increased because of fluorine doping, which indicates that the hydrophobicity of the carbon films could be adjusted to some extent by the fluorine doping. The hardness and elastic modulus of the films remained relatively high (22 GPa) as the fluorine content increased. Furthermore, the friction coefficient of the carbon films was significantly reduced and the wear resistance was enhanced by fluorine doping.

Structural and optical properties of fullerene-like amorphous carbon with embedded dual-metal nanoparticles

Dual-metal nanoparticles were simultaneously embedded into amorphous carbon (a-C) matrix at room temperature. As-deposited Au/a-C/Fe sandwich composite multilayer films were fabricated by alternating multitarget pulsed laser deposition. More sp2 carbon content, narrower Tauc optical gap and stronger photoluminescence intensity of the amorphous carbon films were observed after metal-embedding. Especially for Au/a-C/Fe sandwich films, the fullerene-like microstructure demonstrated that the dual-metal embedding modulated greatly the intrinsic structure and properties of the a-C films. These results were attributed primarily to the extended state around the metal deep level in the band gap and the narrowing of the π and π∗ band edge states. The metal deep level defects contributed chiefly to non-radiative recombination.

The Structure and Bonding State for Fullerene-Like Carbon Nitride Films with High Hardness Formed by Electron Cyclotron Resonance Plasma Sputtering

The Structure and Bonding State for Fullerene-Like Carbon Nitride Films with High Hardness Formed by Electron Cyclotron Resonance Plasma Sputtering

Network structures of fullerene-like carbon core/nano-crystalline silicon shell nanofibers as anode material for lithium-ion batteries

Fullerene-like carbon (FLC) nanoparticles were prepared by depositing soot of burning castor oil. FLC core/nano-crystalline silicon (nc-Si) shell nanofibers with network structures have been fabricated by electrospinning and plasma enhanced chemical vapor deposition techniques. The morphologies and structures of the materials were characterized using scanning electron microscopy, transmission electron microscopy, and micro-Raman spectroscopy. It was demonstrated that the FLC core/nc-Si shell nanofibers on nickel foam can be used as electrode for lithium-ion batteries without adding any binding or conducting additives. High reversible specific capacity of 1164mAhg−1 is retained after 50 discharge/charge cycles at a constant current density of 100mAg−1. The electrode delivers prolonged cycle life and enhanced rate capability compared to pristine nc-Si film. The improved electrochemical performance could be attributed to that the FLC core provides facile strain relaxation to accommodate the large Si volume expansion and shrinkage during lithium-ion insertion and extraction.

The Structure and Bonding State for Fullerene-Like Carbon Nitride Films with High Hardness Formed by Electron Cyclotron Resonance Plasma Sputtering

We studied pure carbon films and carbon nitride (CN) films by using electron cyclotron resonance (ECR) sputtering. The main feature of this method is high density ion irradiation during deposition, which enables the pure carbon films to have fullerene-like (FL) structures without nitrogen incorporation. Furthermore, without substrate heating, the ECR sputtered CN films exhibited an enhanced FL microstructure and hardness comparable to that of diamond at intermediate nitrogen concentration. This microstructure consisted of bent and cross-linked graphene sheets where layered areas remarkably decreased due to increased sp3 bonding. Under high nitrogen concentration conditions, the CN films demonstrated extremely low hardness because nitrile bonding not only decreased the covalent-bonded two-dimensional hexagonal network but also annihilated the bonding there. By evaluating lattice images obtained by transmission electron microscopy and the bonding state measured by X-ray photoelectron spectroscopy, we classified the ECR sputtered CN films and offered phase diagram and structure zone diagram.

Metal incorporation strategies in DLC (fullerene-like) thin films grown by ECR-CVD

The main aim of this work is the comparison among different methods for metal incorporation in Diamond-Like Carbon (DLC, fullerene-like) Carbon for improving the tribological properties. The films have been grown by Electron Cyclotron Resonance Chemical Vapour Deposition (ECR-CVD) applying a negative bias voltage to the substrate. Structural characterization of the samples was performed by Raman spectroscopy and SEM microscopy. The tribological behaviour (friction coefficient and wear) was evaluated by pin-on-disc tests. We have dealt with several approaching methods for the introduction of metal (Cr, Mo) during the growth of carbon coatings. Metallic atoms supply has been provided in two approaches: a) by placing a target (bulk or biased-mesh) inside the deposition system ( in-situ methods), or b) from nanoparticles dispersions ( ex-situ). The metal-containing films present a low friction coefficient roughly similar to the reference DLC film. When in-situ methods are applied lower wear strength has been detected. Otherwise, we have seen that the incorporation of Cr nanoparticles, coming from 300 ppm ethanol dispersion, produces a significant improvement in the tribological behaviour of the sample, as shown by the severe increase in the sliding distance until coating rupture. Therefore, from the comparison among the three different methods we can infer the clear key role played by the incorporated metal nanoparticles into fullerene-like carbon films for the improvement in the tribological properties of the nanocomposites.

Deposition of hard elastic hydrogenated fullerenelike carbon films

Hydrogenated fullerenelike carbon (H-FLC) films, with high hardness of 41.7 ± 1.4 GPa and elastic recovery of ∼75.1%, have been uniformly deposited at low temperature by pulse direct current plasma enhanced chemical vapor deposition (pulse DC PECVD). The superior mechanical properties of the H-FLC films are attributed to the unique curvature and interconnection of graphitic basal planes. We propose the fullerenelike structures are formed in the far nonequilibrium pulse plasma environment and stabilized in the sequential fast quenching process. It is expected that the facile deposition of H-FLC films will promote the large-scale low-temperature preparation of engineering protective films for industrial applications.