Onion-like Carbon Research Articles

Mechanism of phase transition from OLCs with different structures to nPCD at high temperature and high pressure

The molecular dynamics (MD) calculation and experimental research methods were used to study the phase transition from onion-like carbon (OLC) with and without a diamond crystal core to nano-polycrystalline diamond (nPCD) under high temperature and high pressure (HTHP) conditions. The results showed that the transformation from OLC to nPCD was mainly a diffusionless transformation at the heating stage and a diffusional transformation at the cooling stage. There were two main paths for diffusionless transformation from the OLC phase to nPCD. The path (PATH1) was that the diamond grew along the graphite crystal direction [002] with the coherent interface formed by the cubic diamond crystal plane (111) parallel to the graphite crystal plane (002). Another path (PATH2) was that the diamond grew along the graphite crystal direction [120] with the coherent interface formed by the cubic diamond crystal plane (11–1) intersecting the graphite crystal plane (002). The initial path of diffusionless transformation of OLC with and without a diamond core was PATH1 and PATH2, respectively. Increasing the PATH1 phase variable can reduce the sintering conditions of the OLC phase to nPCD. The twin boundary content of nPCD can be improved by increasing the grain size consistency of the OLC and the stacking faults density of the OLC structure.

Regulating the fretting behavior of diamond-like carbon films by changing the composition and structure

Reducing or eliminating the slip regime and mix regime is an effective way to reduce the fretting wear, while the diamond-like carbon (DLC) film, as a self-lubricating solid lubricant, can reduce friction coefficient while improving the surface strength. The most valuable thing is that DLC film can change the film's composition, structure, and physical and chemical properties by controlling its deposition process. This regularability can realize the reduction or elimination of slip regime and mix regime under different fretting conditions, so it is important to explore the changing regulation law of the fretting regime by changing the sp2/sp3 hybrid bond content ratio and microstructure of DLC film. Here, DLC films with different sp2/sp3 hybrid carbon content ratios were obtained by annealing; the fretting performance was studied under different normal loads and amplitudes. The following rules are obtained by drawing the running conditions fretting map and analyzing the tangential stiffness, friction coefficient and dissipation energy: with increasing the sp2/sp3 hybrid carbon content of DLC film, the fretting regime moves towards the slip regime, while the friction coefficient and dissipated energy will increase. In addition, the short-range ordered microstructure, such as onion-like carbon structure, will facilitate the fretting regime towards the partial slip regime. This work demonstrates the controllability and potential of DLC films in fretting.

Visible-light promoted hydrogen production by diesel soot derived onion like carbon nanoparticles

Visible-light-driven photocatalytic water splitting has always been considered a promising approach to hydrogen generation. The onion-like carbon nano particles (OCNPs) isolated from diesel engine exhaust soot have shown their strong capability towards the visible-light promoted hydrogen evolution via water splitting. Under visible light irradiation, the hydrogen evolution rate of OCNPs is ∼1075 μM h−1 g−1 which is quite comparable with the available literature without using any dopant materials or co-catalyst. The evolution of hydrogen using the OCNPs is due to the presence of numerous optically active centers and a high sp3/sp2 interface on the surface of OCNPs, which promoted the process of visible-light assisted photocatalytic water splitting. These waste derived OCNPs can serve as high-performance photocatalytic materials for the visible light-to-hydrogen production and could contribute towards the goal to achieve clean energy.

Electrochemical conversion of natural graphite minerals into carbon nanostructures incorporated with Fe3Si for Li-ion storage application

Natural graphite mineral (NGM) is an abundant and low-cost carbon source with the potential of being employed as the precursor for producing high-quality carbon nanostructures for energy storage applications. In this article, one-pot electrochemical conversion of NGM into graphitic carbon nanostructures incorporated with Fe3Si nanocrystals with enhanced bulk electrical conductivity and Li-ion storage performance is reported. To this end, electrodes made of NGM are negatively polarized in molten LiCl-NaCl at 740 °C under various cathode current densities. At 1 A cm−2, the high-yield conversion of the mineral into carbon nanotubes (CNTs), nanofibers and onion-like carbon nanoparticles is realized. The product exhibits a specific electrical conductivity of 9.83 S m2 g−1, and the Li+ transfer resistance of 24 Ω. The Li-ion storage capacity of the material is evaluated to be high at 382 mAh g−1 after 220 Li-ion insertion and extraction cycles under the current density of 200 mA g−1, making the material an attractive low-cost candidate for the anode of lithium ion batteries. The ferromagnetic behavior of the nanostructured Fe3Si incorporated carbon is characterized by the saturation magnetization of 11.1 emu g−1, potentially promoting the recyclability of spent anode material. This article reports on the green and low-cost conversion of NGMs into nanostructured carbon materials with enhanced Li-ion storage performance.

Poly(tannic acid)-functionalized onion-like carbon nanoparticles derived from candle soot serving as potent lubricant additives

Spheroidal onion-like carbon (OLC) nanoparticles exhibit heliocentric graphitic layers are known to possess excellent lubricating properties. Herein, tannic acid (TA) was assembled in-situ onto the onion-like carbon material with Tris (2-aminoethyl) amine (TAEA) to form poly(tannic acid)-functionalized onion-like carbon nanoparticles (P(TA-TAEA)@OLC) via Schiff-base reaction and/or Michael addition. Subsequently, the commercial lubricating additive dialkyl dithiophosphate (DDP) was introduced via Michael addition to bond with the poly(tannic acid) of P(TA-TAEA)@OLC nanoparticles in Tris aqueous solution, to obtain DDP-functionalized onion-like carbon (DDP@OLC) nanoparticles. The as-obtained DDP@OLC nanospheres in the role of lubricating additives demonstrated remarkable friction reduction and wear resistance. With addition of 1 wt % DDP@OLC nanoparticles, the coefficient of friction reduced from 0.17 to 0.10, while the corresponding wear volume loss decreased by 96 %, and the loading capacity reached 600 N from 100 N. The outstanding tribological performance of these as-obtained nanoparticles can be attributable to the formation of a graphitic layer exfoliated from OLC nanoparticles under a high load, and the protective film derived from tribochemical reactions via N, P and S elements of DDP@OLC. Meanwhile, the DDP@OLC nanoparticles can also act as spacers and ball bearings between sliding surfaces, facilitating the enhancement of anti-wear and friction reduction properties.

Preparation and electrothermal performance of onion-like carbon/carbon nanofibre composite film

An onion-like carbon/carbon nanofibre composite film was prepared by electrospinning. Its precursor application, and the effect of the amount of onion-like carbon additive and carbonization temperature on the physical and chemical properties of onion-like carbon/carbon nanofibre composite film was investigated. The results showed the non-woven fabric obtained by electrospinning solution reagent and the non-woven fabric after pre oxidation can be used to prepare facial mask and adsorb methylene blue (the adsorption rate reaches 83.1%) respectively. The conductivity of the onion-like carbon nanofibre composite film increased with the onion-like carbon content. The electrical conductivity of the composite film with an onion-like carbon content of 20 wt% (1.76 S/cm) was 1.5 times that of pure carbon nanofibres (1.12 S/cm). As the carbonisation temperature increased, the conductivity also increased. The prepared onion-like carbon/carbon nanofibre composite film exhibited an excellent electrothermal conversion performance. When the voltage was 30 V, and the current was 2.79 A, the surface temperature of the onion-like carbon/carbon nanofibre composite film (the carbonisation temperature was 1100 °C, and the content of onion-like carbon was 20 wt%) was as high as 588.4 ℃.

In-situ formation of onion-like carbon film by tribo-induced catalytic degradation of hydrocarbon: Effect of lubrication condition and load

The method of extracting a carbon-based film from a lubricating medium has attracted considerable interest due to its sustainable lubrication capabilities. However, the effect of the lubrication conditions and applied loads on the in-situ formation mechanism of the carbon-based film remains unknown. Here, the tribological properties of the MoN-Ag coating lubricated with octadecane, oleic acid, and 1-octadecene were investigated using a ball-on-disk tribo-tester. The MoN-Ag coating's tribo-induced catalytic effects in these lubricating mediums were revealed by SEM-EDS, Raman, XPS, and TEM analysis. The results showed that the MoN-Ag coating could frictionally induce the degradation of these lubricating mediums to generate carbon-based film with an amorphous/onion-like structure. And the coating had a better tribo-induced catalytic effect in octadecane than the other lubricating mediums. In combination with the first-principles simulation, it was indicated that the in-situ formation ability of the carbon film depended on the lubricating medium's functional groups and adsorption energy. These findings refined the design theory of the tribo-induced catalytic system and introduced a novel concept for the selection of lubricating medium in engineering applications.

Antibacterial Effect of Carbon Nanomaterials: Nanotubes, Carbon Nanofibers, Nanodiamonds, and Onion-like Carbon.

The increasing resistance of bacteria and fungi to antibiotics is one of the health threats facing humanity. Of great importance is the development of new antibacterial agents or alternative approaches to reduce bacterial resistance to available antibacterial drugs. Due to the complexity of their properties, carbon nanomaterials (CNMs) may be of interest for a number of biomedical applications. One of the problems in studying the action of CNMs on microorganisms is the lack of universally standardized methods and criteria for assessing antibacterial and antifungal activity. In this work, using a unified methodology, a comparative study of the antimicrobial properties of the CNM systemic kit against common opportunistic microorganisms, namely Escherichia coli and Staphylococcus aureus, was carried out. Multiwalled carbon nanotubes (MWNTs), catalytic filamentous carbon with different orientations of graphene blocks (coaxial-conical and stacked, CFC), ionic carbon (OLC), and ultrafine explosive nanodiamonds (NDs) were used as a system set of CNMs. The highest antimicrobial activity was shown by NDs, both types of CFCs, and carboxylated hydrophilic MWCNTs. The SEM results point out the difference between the mechanisms of action of UDD and CFC nanotubes.

Screening out the Transition Metal Single Atom Supported on Onion-like Carbon (OLC) for the Hydrogen Evolution Reaction

A recent experiment has confirmed that onion-like nanospheres of carbon (OLC) covered with single Pt atoms show comparable hydrogen evolution reaction (HER) catalytic activity to the commercial Pt/C. In this work, we have performed screening calculations on the single transition metal (TM) atom supported on OLC (a total of 26 candidates) using the density functional theory (DFT) to find excellent HER catalysts. Our calculated results indicate that the Nb1/CLO, Mo1/CLO, Ru1/CLO, Rh1/CLO, Pd1/CLO, and Ir1/OLC show high-efficient catalysts performance for the HER, as experimental Pt1/OLC does. We also try to seek an appropriate descriptor relevant to the Gibbs free energies, and the average local ionization energy (ALIE), which is first used to predict HER activity, shows a perfect linear correlation with Gibbs free energy. It is interesting to note that the ALIE descriptor is more successful than the commonly used d-band center.

Microstructure of onion-like carbon fabricated in vacuum by annealing ND

The relationship between annealing temperature, holding time and the structure of Onion-like carbon (OLC) in a certain atmosphere was the key to the industrial preparation of OLC. OLCs with various structures were fabricated in a vacuum by annealing detonation nanodiamond (ND) in the conditions of 900–1600 °C/0–2 h/30 °C·min −1 /1.0 × 10 −1 Pa. XRD, Raman, HRTEM, TG-DSC, and FTIR were used to characterize the composition, bond types, microstructure, thermal stability and surface adsorption properties of OLCs. It had been shown that increasing the annealing temperature or extending the holding time increases the graphite content and the average grain size of OLCs and decreases the average ND core size of OLCs. The annealing temperature determined whether the ND core was present in the OLC, and the holding time allowed the OLC to reach the stable phase. When the annealing temperature was less than 1400 °C, the OLC mostly existed in spherical and elliptic structures and had an ND core inside. The ND core in the OLC cannot vanish even if the holding time was extended. When the temperature exceeds 1400 °C, OLC mostly existed in ellipse and polygon structures and did not have an ND core inside. OLC without ND core had higher oxidation resistance and lower adsorption capacity due to the integrity of its concentric graphite shell structure. This work provided a feasible method for batch preparation of OLC with a controllable structure. • Batch preparation of OLC with controllable structure. • The direct relationship between the annealing parameters and the grain size, shell number, interlayer space, residual diamond core size and graphite content of OLC was investigated systematically and detailedly. • The mechanism and trade-off of annealing parameters effects on the microstructure and composition of OLC were revealed.

Onion-Like Carbon Nanoparticles as Additives in Lubricant Oil Deform Inelastically During the Wear Testing for Improved Lubrication Performances

Onion-Like Carbon Nanoparticles as Additives in Lubricant Oil Deform Inelastically During the Wear Testing for Improved Lubrication Performances

Ternary PdNiO nanocrystals-ornamented porous CeO2/onion-like carbon for electrooxidation of carbon monoxide: unveiling the effect of supports and electrolytes

Porous ternary Pd-based catalysts at low Pd mass exhibit inimitable surface area, accessible active sites, and tunable electronic structure advantageously utilized for high CO oxidation (COoxid) activity and stability in different electrolyte media.

Onion-like carbon with controllable carbon atom hybridization embedded in BiVO4 photoanode for enhanced photoelectrochemical water splitting

BiVO4 with a suitable energy band structure is one of the most promising substrates for photochemical water spitting, but a significance limitation is its severe recombination of photogenerated electron-hole pairs in the bulk. Herein, we present a strategy of incorporating an onion-like carbon (OLC) into bulk BiVO4 matrix to enhance its carrier separation. The OLC, with controlled sp2/sp3-carbon ratio, can facilitate the bulk charge separation and UV–vis light absorption of BiVO4. The carrier separation enhancement in BiVO4 is highly dependent on the sp2/sp3 ratio of OLC, which falls within the range of 3 % to 89 %. The BiVO4/OLC photoanode embedded by OLC with sp2-carbon content of 40 % exhibits the champion photocurrent density of 4.8 mA cm−2 (1.23 VRHE), compared to the pristine BiVO4 of 2.84 mA cm−2. This work not only demonstrates a strategy for enhancing the photocatalytic carrier separation of BiVO4 photoanode by incorporating OLC, but it also provides a comprehensive understanding of the function mechanism of carbon-based materials in photocatalysts.

Onion-like Carbons Provide a Favorable Electrocatalytic Platform for the Sensitive Detection of Tramadol Drug.

This work reports the first study on the possible application of nanodiamond-derived onion-like carbons (OLCs), in comparison with conductive carbon black (CB), as an electrode platform for the electrocatalytic detection of tramadol (an important drug of abuse). The physicochemical properties of OLCs and CB were determined using X-ray diffraction (XRD), Raman, scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), and thermogravimetric analysis (TGA). The OLC exhibits, among others, higher surface area, more surface defects, and higher thermal stability than CB. From the electrochemical analysis (interrogated using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy), it is shown that an OLC-modified glassy carbon electrode (GCE-OLC) allows faster electron transport and electrocatalysis toward tramadol compared to a GCE-CB. To establish the underlying science behind the high performance of the OLC, theoretical calculations (density functional theory (DFT) simulations) were conducted. DFT predicts that OLC allows for weaker surface binding of tramadol (E ad = -26.656 eV) and faster kinetic energy (K.E. = -155.815 Ha) than CB (E ad = -40.174 eV and -305.322 Ha). The GCE-OLC shows a linear calibration curve for tramadol over the range of ∼55 to 392 μM, with high sensitivity (0.0315 μA/μM) and low limit of detection (LoD) and quantification (LoQ) (3.8 and 12.7 μM, respectively). The OLC-modified screen-printed electrode (SPE-OLC) was successfully applied for the sensitive detection of tramadol in real pharmaceutical formulations and human serum. The OLC-based electrochemical sensor promises to be useful for the sensitive and accurate detection of tramadol in clinics, quality control, and routine quantification of tramadol drugs in pharmaceutical formulations.

Molecular Dynamical Investigation of Lithium-Ion Adsorption on Multilayer Fullerene

As the cathode of lithium-ion batteries, carbon material has been the focus of research. At present, diverse investigations have been carried out on the lithium convergence behavior in the carbon material family. As a new carbon material, multilayer fullerenes have been shown in various experimental studies to have a high discharge rate as an electrode, indicating that onion-like carbon has the potential to release energy quickly. Materials and mechanical scientists are increasingly interested in lithium-ion batteries. In this paper, the molecular dynamics (MD) method was used to simulate the absorption of lithium ions by multilayer fullerenes. A model of five layers of fullerenes was established to compare the lithium-ion absorption rates of multiple layers of fullerenes at different lithium-ion concentrations. The effects of the lithium-ion diffusion rate on the results were considered. In addition, the effects of the number of lithium ions, the velocity, and the layer number of multilayer fullerenes on the structural behavior and stress were investigated thoroughly when the multilayer fullerenes adsorbed lithium ions.

Enhanced microwave absorption performances of onion-like carbon coated FeNiCoCuTi high-entropy alloys nanocapsules

High entropy alloys (HEAs), a new type of functional material, are rarely applied to prepare core-shell structured nanocomposites. In this work, FeCoNiCuTi@C nanocapsules have been prepared by arc discharging HEAs ingot under the atmosphere of methane, displaying the sphere shape with the average diameter of 72.1 nm and ~ 3 nm onion-like carbon shell and the single FCC phase. The melting points, crystal structure and electronegativity play the important role on determining the element composition and atomic percentage. Carbon facilitates protecting magnetic elements, improving EM parameters and enhancing resonance frequency. Good impedance matching, strong electromagnetic loss ability and large attenuation constant ensure the microwave can enter the nanocapsules to the largest extent and could be consumed. These advantages provide the basis for the excellent microwave absorption performance ( effective bandwidth of 5.52 GHz at 1.9 mm, maximal reflection loss of −37.78 dB and absorption efficiency of 52.41 dB·GHz/mm at 1.8 mm) of FeCoNiCuTi@C nanocapsules. • FeNiCoCuTi high-entropy alloys nanocapsules with onion-like carbon are prepared. • Core/shell structure leads to good impedance matching, strong attenuation and loss. • Effective bandwidth is 5.52 GHz at 1.9 mm and absorbing efficiency is 52.4 dB GHz/mm.

Double-Layer Superhydrophobic Anti-Icing Coating Based on Carbon Nanoparticles

The previous article introduced the idea of a superhydrophobic coating from carbon nanoparticles that can combine the lotus effect, the slip effect and electric current heating. A further development of this idea was suggested. The article demonstrated the possibility of a practical implementation of the suggested approach using two coating layers—the electro-thermal layer from carbon nanotubes and the water-repellent layer from onion-like carbons. This coating allows to conserve energy during periods of slight cooling simply due to the use of the lotus effect. The heating is used to prevent icing at lower temperatures. The best contact angle achieved equals 155.9 ± 0.5 degrees at a slip start angle of 1.2 ± 0.5 degrees.

Onion-like carbon as nano-additive for tribological nanogenerators with enhanced output performance and stability

Triboelectric nanogenerators (TENGs) with sliding-mode have developed rapidly in the field of energy harvesting and sensing. However, its surface wear and low electric output performance usually limit its applicability. Herein, a mixture of hexadecane with onion-like carbon (OLC) lubricant is added to the interface between polytetrafluoroethylene (PTFE) film and steel to enhance the triboelectrical and tribological performance. During dry friction, the friction pair is severely worn and the current output decreases gradually with the transfer of a large amount of PTFE debris in a short period. The introduction of hexadecane partly resolves the problems such as friction and wear with the reduction in the transfer of PTFE material. However, the current output decreases gradually during the friction process because there is still some slight material transfer in the interface. The electrical output of TENG is further enhanced with the addition of OLC, and its tribological properties are comparable or better than oil-based TENG. The short-circuit currents (Isc) of the oil-based TENG and the oil-OLC-based TENG are 1.5 times and 5 times that of the TENG in the dry friction state, respectively. Also, the coefficient of friction (COF) of oil-OLC-based TENG is reduced by about 75.3% compared with dry friction state. The oil-OLC-based lubricant reduces the transfer film formation, increases the effective contact area, and squeezes the air at the interface. Also, part of the OLC rolls between the two friction layers, forming a "micro-bearing", further reducing the generation of transfer film. This study provides a novel way to improve the output efficiency and prolong the service life of TENG.

Onion-like Carbon (OLC), Iron, Cobalt and Nitrogen X-Ray Absorption Spectroscopy (XAS) Data Analysis

This project was about analyzing the data of the X-Ray Absorption Spectroscopy (XAS) of several synthesis of modified Onion-like Carbon (OLC) nanoparticles with nitrogen conductive polymers to study different catalysts for the Oxygen Reduction Reaction (ORR). Also, observing differences in the oxidation state, geometry, iron and cobalt bonds, and structures between the samples at different potentials were some of the objectives in this investigation. The PyMca program was used to normalized the samples and transferred the scan’s data. In Athena for the X-Ray Absorption Near Edge Structure (XANES) region, the scans were merged for every sample individually by adjusting the pre-edge, post-edge, spline range in “k”, and the normalization order parameters. Subsequently, Artemis for the Extended X-Ray Absorption Fine Structure (EXAFS) region was used to fit the first and second shell of the samples used in Athena. Here we used a FEFF calculations file from a Cobalt Oxide and Iron Oxide compounds that have similar elements to the ones in our samples. As results, we have been able to fit the N-OLC/FeCo (1:3)-Co and N-OLC/FeCo(1:3)-Fe. In both cases the fits from the first shell were from Co-O and Fe-O bonding interactions and the fits from the second shell were from Co-Co and Fe-Fe bonding interactions between the atoms.

Electrochemical Conversion of Natural Graphite into Carbon Nanostructures for Energy Storage Applications

Natural graphite minerals with global reserves greater than 320 million tones can be considered as low-cost and highly available precursors for the preparation of high-quality carbon nanostructures with potential applications in energy devices and related areas. Here, the electrochemical conversion of natural graphite minerals into carbon nanostructures, comprising onion-like carbon nanoparticles and multiwall carbon nanotubes (MWCNTs) in high-temperature molten salts are studied. The galvanostatic polarization of electrodes made of such minerals is conducted in molten LiCl and LiCl-NaCl at various current densities, leading to the exfoliation of the minerals into carbon nanostructures. The influence of non-carbon impurities present in the natural graphite mineral, and the current density applied on the characteristics of the resultant nanocarbons are investigated. Moreover, the structural and microstructural properties of the nanocarbons fabricated using natural graphite minerals are compared with those produced using commercially pure graphite electrodes. It is found that the electrochemical nanostructuring of the mineral in molten salt not only increases the surface area of the material, but also increases its electrical conductivity. The high-yield conversion of the mineral into carbon nanostructures is realized at the cathode current density of around 1 A cm-2. The Li- and Na- ion storage performances of this sample are evaluated. The Li-ion storage capacity of the sample is found to be remarkable at around 460 mAh g-1 after 500 charge/discharge cycles at the current density of 200 mA g-1. The green molten salt preparation and the electrochemical performance of nanocarbons is discussed here.