Spherical Carbon Nanoparticles Research Articles

Synthesis of spherical carbon nanoparticles from orange peel and their surface modification with chitosan: Evaluation of optical properties, biocompatibility, antioxidant and anti-hemolytic activity

Synthesis of spherical carbon nanoparticles from orange peel and their surface modification with chitosan: Evaluation of optical properties, biocompatibility, antioxidant and anti-hemolytic activity

Effects of quenching rate on the plasma gas-phase synthesis of graphene: Insight from the experiments and ReaxFF studies

This investigation analysed the effects of quenching rate on the plasma gas-phase synthesis of graphene. The quenching rate was modulated by the flowrate/type of radial gas whish was injected in the plasma downstream. The experimental results showed that the plasma pyrolysis of acetylene produced spherical carbon nanoparticles. The content graphene flakes in the products increased with the quenching effect, and the layer number of graphene decreased accordingly. Further characterisation confirmed that a high quenching rate increased the crystallinity of the product, reduced the amorphous carbon content, and resulted in better oxidation resistance. The graphene formation pathway was carried out by the molecular dynamics simulations (ReaxFF), focusing on the effect of the quenching rate on graphene growth. As the quenching rate increased, the decrease in the time for surface reactions lowered the generation of five- and seven-membered rings, reducing the possibility of edge growth bending. Besides, an increased quenching rate rapidly lowered the growth temperature and thus retarded the C–H bond breakage at the edges of the carbon clusters. The C–H bonds terminated C–C bond formation at the edges of the carbon clusters, preventing edge growth bending of the carbon clusters, and thus contributing to the growth of lamellar structure. These results suggested that increasing the quenching rate is an effective method for regulating the plasma gas-phase synthesis of graphene.

93 Linking the Molecular Mechanisms of Alveolar Macrophage Cell Death Induced by Inhaled Nanoparticles with the Subsequent Pathological Outcome

Abstract Background Carbon Nanomaterials (CNM) get released into the environment as combustion by-products and engineered materials. Our previous work has shown that inhalation of CNMs differing in shape, such as spherical carbon nanoparticles (CNPs) or fiber-shaped nanotubes (CNTs) triggers different response pattern ranging from acute and resolving to persistent and chronic lung inflammation. Furthermore, our cell and mouse data showed that, particularly rigid, multi-walled nanotubes (MWCNTs) can cell-specifically and persistently kill alveolar macrophages (AM). Here we hypothesize that the AM death pathway determines the fate of lung inflammation, as acute or chronic. Results Exposure of the murine AM cell line MH-S to MWCNT led to significant decrease of cell viability in a dose-dependent manner (IC50: 10±5 μg/ml). In comparison, CNPs showed relatively low toxicity (IC50: >200 ug/ml) to MH-S cells. Also in contrast to hardly detectable apoptosis (cleaved-Caspase3), immunoblot and -fluorescence analysis demonstrated significant induction of LC3II, a central protein in the autophagy pathway, 12h after MWCNT treatment. The MWCNT triggered cell death response from BMDM-derived AM-like cells however, did not differ between LC3B-/- and wt mice, indicating the autophagy pathway as dispensable. In contrast, inhibition of lysosomal Cathepsins via K777, rescued MWCNT induced cell death of either MH-S or AM-like cells suggesting lysosomal Cathepsins as key player in AM cell death. Conclusion Lysosomal damage with subsequent Cathepsin activity seem a central key event in MWCNT triggered AM cell death. Current studies investigate the relevance of Cathepsins for the inflammatory consequences of CNT triggered AM cell death.

Formation and electrochemical properties of ternary mesoporous carbon, coordination C60Pd polymer and palladium nanoparticle composites

This work describes the preparation and properties of composites based on spherical mesoporous carbon nanoparticles and fullerene-coordinated C60Pd polymer. The composite material was synthesized under a multistep chemical procedure. In the first step, mesoporous carbon nanoparticles were synthesized via a template-assisted method. Next, the C60 fullerene was incorporated into mesoporous carbon pores, and then the polymerization process was carried out in a solution containing a Pd(0) complex. The composite material is electroactive in the negative potential range due to the faradaic reduction process of C60 moieties. At less negative potentials, a high capacity current related to the presence of mesoporous carbon is observed. Under voltammetric conditions, this system exhibits a high capacitance equal to 359 F g−1 in the potential range of C60Pd reduction at 0.1 V s−1. This value is 3 times higher than that of the pure polymeric material. Moreover, the composite system is more stable than pristine C60Pd. Capacitance retention, in this case, is approximately 30% higher than that of the C60Pd polymer after 6000 charging/discharging cycles at current density of 6.7 A g−1.

Simulations of plasticity in diamond nanoparticles showing ultrahigh strength

We use molecular dynamics (MD) simulations to deform single crystal spherical carbon nanoparticles (NP), 4–45 nm diameter, with a hard, flat indenter, compressing along the [001] direction. There is no clear amorphization nor phase change in the NP, but there is significant deformation, with bent crystalline planes, and many atoms that retain sp3 coordination, but are no longer recognized as having diamond structure by different structure-identification methods. Machine-learning is used to improve diamond-structure identification. The NP deforms laterally, and volumetric strain is ~0.1 when the uniaxial strain is ~0.5. Poisson's ratio increases with strain, and the elastic limit is reached at 0.2–0.3 strain, at a contact pressure of ~150 GPa. For NPs above 5 nm, dislocations appear and are mostly (1/2)<110>{111} full dislocations, with a few partial dislocations for larger nanoparticles, without twinning. These results agree with the recent observation of plastic deformation in diamond nanopillars. Small NP display elastic modulus, yield stress and hardness increasing with NP size, but NPs with diameter larger than 25 nm display an approximately constant dislocation and dislocation junction density, which leads to a plateau in the hardness versus NP size, at ~150 GPa, close to bulk diamond. Diamond nanoparticles could provide high strength thin coatings, lighter than full-density nanotwinned diamond but with nearly the same strength.

Design and fabrication of novel flexible sensor based on 2D Ni-MOF nanosheets as a preliminary step toward wearable sensor for onsite Ni (II) ions detection in biological and environmental samples

Herein, for the first time, an innovative and sensitive flexible sensor for efficient potentiometric monitoring of Ni (II) ions has been designed and developed. The developed flexible sensor is constructed from highly porous activated flexible carbon cloth decorated with nitrogen and spherical porous carbon nanoparticles derived from low-cost cotton doped with polypyrrole nanoparticles via simple carbonization-activation process followed by dip-coating in membrane cocktail containing 2D Ni-MOF nanosheets as an electroactive material. The developed flexible sensor affords rapid, accurate and stable response for the Ni (II) ions monitoring at its trace level in the biological fluids including human saliva and sweat samples in addition to tap water as an environmental sample without any preconditioning steps over pH range of 2–8 with detection limit of 2.7 × 10−6. Additionally, the flexible sensor shows good antibacterial properties against both of Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria presenting safe handling for human skin as a flexible sensor for wearable system applications. This study presents a forward step for the fabrication of a wearable sensor for rapid onsite monitoring of Ni (II) ions in biological and environmental samples.

A metal-doped flexible porous carbon cloth for enhanced CO2/CH4 separation

• Smart porous flexible magnetic carbon sieves were developed. • Flexible carbon sieve decorated with carbon nanoparticles rich with N was developed. • Ni nanorodes were decorated on flexible porous carbons inducing magnetic features. • Outstanding CO 2 /CH 4 selectivity of 369.5 was achieved for natural gas upgrading. From a practical perspective, carbon adsorbents are mostly prepared to form functional components from carbon powder by using binders or hot pressing, which results in the degradation of its textural properties. Thus, the flexible activated porous carbon cloths have attracted increasing interest in recent years because these are easier to handle than powder and granular materials when constructing more conformable and efficient membrane device designs. In this work, a metal-doped flexible porous carbon cloth with outstanding CO 2 /CH 4 selectivity was developed. Carbon cloth deposited with spherical porous carbon nanoparticles and doped with nitrogen was prepared from viscose rayon cloth decorated with polypyrrole nanoparticles. Then, this flexible carbon cloth was doped with nickel. Two samples with moderate Ni content (7 and 10 wt%) were used to investigate the fundamental magnetic properties and CO 2 /CH 4 separation performance. These two samples have both antiferromagnetic and ferromagnetic properties, and it is originated from the different ratios of NiO and pure Ni. The Ni(O) contents in the flexible carbon cloth influenced the CO 2 and CH 4 sorption properties and separation performance as well. Based on the ideal adsorbed solution theory (IAST) model, the developed metal-decorated flexible activated carbon cloth shows 13 times better separation performance than Ni-free sample and achieved CO 2 /CH 4 (1:1) selectivity of 369.5 and 70.7 at 20 and 1 bar, respectively, at 298 K, which is among the highest selectivity values reported for porous carbon materials so far.

Biodistribution of Mesoporous Carbon Nanoparticles via Technetium-99m Radiolabelling after Oral Administration to Mice.

The use of ordered mesoporous matrices, and in particular carbon-based mesoporous nanoparticles has shown great potential towards enhancing the bioavailability of orally administered drugs. Nevertheless, elucidation of the in vivo absorption, distribution, and excretion of such carriers is essential for understanding their behaviour, and radiolabelling provides a very useful way to track their occurrence inside the body. In this work, uniform spherical CMK-1-type ordered mesoporous carbon nanoparticles have been radiolabelled with Technetium-99m (99mTc) and traced after oral administration to mice. Ex vivo biodistribution studies showed that the radiolabelled nanoparticles accumulated almost exclusively in the gastrointestinal tract; complete elimination of the radiotracer was observed within 24 h after administration, with practically no uptake into other main organs. These findings along with the results from in vitro stability studies indicate that the spherical carbon nanoparticles examined could be safely used as drug carriers with minimal side effects, but also support the great value of radiolabelling methods for monitoring the particles’ behaviour in vivo.

Development of graphitic lubricant nanoparticles based nanolubricant for automotive applications: Thermophysical and tribological properties followed by IC engine performance

Two types of new carbon nanostructures with the graphitic structural unit were synthesized viz. nanographite (< 50 nm) and spherical carbon nanoparticles (~10 and ~ 50 nm). The above two nanoparticles and micro graphite were used as an engine oil additive to enhance the tribological properties. The tribological and thermophysical properties of all lubricants were also evaluated. The tribological tests exhibits enhancement seven times in wear and more than 13 times in friction of the nanographite-based nanolubricant. The performance assessment of nanographite-based nanolubricant exhibits reduction in ~15.2% in total fuel consumption, 18% in brake specific fuel consumption, 22% augmentation in brake thermal efficiency, 28.23% enhancement in heat carried by a water jacket, and 5.13% reduction in exhaust gas temperature compared to base engine oil. Marginal to significant reduction in the emission of harmful gases is also observed. The results show the potential of developed nanolubricant for environmental protection and energy-savings.

Co, N co-doped porous carbons as high-performance oxygen reduction electrocatalysts

Although the Co and N co-doped carbon catalyst (Co-NC) has attracted much attention because of its low cost and the natural abundance of the dopants, it has a low oxygen reduction reaction (ORR) activity and a high selectivity for the two-electron (2e-) reduction of oxygen to H2O2, which affects its use in fuel cells. Co-NC catalysts were prepared by the pyrolysis of a mixture of cobalt chloride and chitosan pretreated with zinc chloride at 650, 750 and 850 oC, followed by washing with nitric acid and annealing at 900 oC. The results indicate that zinc chloride helps the complexing of chitosan with Co2+, which is also a chemical activator that generates pores, and annealing caused the evaporation of the spherical Zn metal nanoparticles formed by the carbothermal reduction of Zn ions, leading to a unique porous structure of the catalysts with spherical pores filled with spherical carbon nanoparticles formed by the growth of nitrogen-doped carbon as a result of the Co catalyst. The degree of graphitization is also improved by the Co catalyst. The Co-NC catalyst obtained at a pyrolysis temperature of 750 oCshows the same four-electron (4e-) reduction of oxygen as a commercial Pt/C catalyst, and a significantly higher ORR catalytic activity, longer-term stability and better methanol tolerance than a commercial Pt/C catalyst. These are due to its large specific surface area, high contents of pyridinic nitrogen and graphitic nitrogen that disperse the Co species and its excellent electrical conductivity.

Thermally stable high-contrast iridescent structural colours from silica colloidal crystals doped with monodisperse spherical black carbon particles

The saturation of iridescent structural colours of silica colloidal film is significantly improved by addition of a small amount of the monodisperse spherical black carbon nanoparticles which are uniformly dispersed in a colloidal crystal matrix.

Low-stress diamond-like carbon films containing carbon nanoparticles fabricated by combining rf sputtering and plasma chemical vapor deposition

Carbon nanoparticles (CNPs) incorporated diamond-like carbon (DLC) films have been fabricated by a combination of rf sputtering and plasma chemical vapor deposition. Spherical CNPs with a mean size of 21.2 nm are sandwiched between DLC layers with a mass density of 1.7 g cm−3. The film stress is decreased to 119 MPa, by depositing the CNPs over the base DLC layer at a surface coverage of 10.7%. This reduction is approximately half of that without CNPs. Raman spectroscopy indicates the insertion of CNPs barely alters the bonding structure of the upper DLC layer.

Strategies for Scalable Gas-Phase Preparation of Free-Standing Graphene

The preparation of graphene with high quality serves as a prerequisite for its usage. Traditional methods of graphene production, represented by liquid-phase exfoliation and chemical vapor depositi...

Synthesis of carbon nanoparticles in a non-thermal plasma process

A non-thermal plasma source based on magnetically stabilized gliding arc discharge (MSGAD) was used to prepare carbon nanoparticles via methane decomposition. Spherical carbon nanoparticles (SCNs), few-layer graphene nanoflakes (GNFs), and nitrogen-doped carbon nanoparticles were obtained. The results showed that the product microstructure was influenced by the buffer gas. In pure methane and argon, the products were a mixture of SCNs and GNFs. In helium and hydrogen, all products were highly crystalline GNFs with low defects, few layers, large BET surface areas, and excellent thermal stability. Under a nitrogen atmosphere, nitrogen-doped nanoparticles were formed, and the products were a mixture of GNFs, disordered graphitic layers, and tiny spots similar to carbon dots. The formation of GNFs was possibly related to the high input power and abundant hydrogen atoms, while the complex product morphology obtained under a nitrogen atmosphere was likely caused by the incorporation of nitrogen atoms.

Synthesis of graphene flakes using a non-thermal plasma based on magnetically stabilized gliding arc discharge

The use of non-thermal plasma at atmospheric pressure has emerged as a technique for the substrate-free, gas-phase synthesis of graphene nanoflakes (GNFs). In this paper, a non-thermal plasma based on magnetically stabilized gliding arc discharge (MSGAD) was employed to prepare GNFs. The effects of the carbon-containing precursor, plasma gas, and arc current on the GNFs synthesis were investigated. The technique produced GNFs with sizes of 50–200 nm and 1–20 layers, spherical carbon nanoparticles with 10–40 nm diameters, and graphitic particles. The results showed that the formation of GNFs depended on the selection of proper process parameters, such as precursors with a high H/C ratio, an Ar-N2 plasma gas, a low arc current, a low precursor flow rate, and a suitable plasma gas flow rate. Correlations between the process parameters and the product morphology indicated that abundant H atoms and fewer polycyclic aromatic hydrocarbons were favorable for the formation of GNFs.

Effects of hydrogen/carbon molar ratio on graphene nano-flakes synthesis by a non-thermal plasma process

Few-layer graphene nano-flakes (GNFs) are successfully prepared via hydrocarbon pyrolysis using a non-thermal plasma process based on a magnetically stabilized gliding arc discharge (MSGAD) at atmospheric pressure. The effects of feedstock gas type and hydrogen flow rate on the morphology of carbon nanomaterials are investigated. When the hydrogen/carbon (H/C) molar ratio is 4, the synthesized GNFs consist of 10 layers per stack with dimensions between 100 and 300 nm in a 4.57.2% yield. The energy cost is 0.1–0.2 kWh/g, which makes this process feasible for large-scale GNFs production. The results show that appropriately increasing the H/C molar ratio promotes the morphological transformation of carbon nanomaterials from spherical carbon nanoparticles (SCNs) to GNFs, improve the quality of GNFs and reduce the stacking of graphite layers. However, increasing the H/C ratio reduces the yields of carbon nanomaterials, so as to increase the energy cost. Analysis suggests that increasing the H/C ratio reduces the concentration of polycyclic aromatic hydrocarbon (PAH) and generates more H atoms, which helps form a two-dimensional nucleation and promotes planar growth. However, an excessive H/C ratio may introduce some defects due to an etching effect.

Synthesis of Size-Tunable Spherical Carbon Nanoparticles By Polymerization of Sp-Carbon Rich Precursors and Characterization of Optical Properties for Energy Conversion and Storage Applications

Carbon nanoparticles (CNPs) are considered as one of the most promising materials due to their unique optical and electronic properties for a wide range of applications in the field of optoelectronics, energy conversion/ storage and bio-imaging. The high photoluminescence, photostability and low toxicity of CNPs have made them suitable for various applications. The unique network of hybridized sp2 carbon atoms provides unique properties of CNPs as it allows delocalization of the electrons over the entire surface of the molecule. The studies have shown that the carbon core is responsible for the strong absorption of light while the luminescence comes from the surface sites and the functional groups present on the surface. The functions and properties of the CNPs could be modulated by changing their shape, size and dimensionality. Despite all these advantages, CNPs have been slow to transform from laboratory prototypes into real life industrial scale products because of the difficulty in synthesizing them and in controlling their size. The control over their size is important as the optical properties of CNPs have been shown to be varying with the variation in size. The synthetic methods reported until now involves high-temperature (>100 oC) processes which often results in uncontrolled shape, size, polydisperse and chemically inert nanoparticles, which makes it very difficult to modulate their optical, electronic and morphological properties. Thus, the development of low-temperature, controlled synthesis is desirable.We report the development of new synthetic methods for the preparation of carbon nanoparticles allowing precise control of their shape, size and properties by polymerization of sp-carbon rich precursors. These precursors (butadiyne and acetylene) tend to become thermodynamically unstable when polymerized to long polyyne chains and decompose inside the reaction mixture to give CNPs. Hence, these polyyne intermediates provide us the control over the size of CNPs during the reaction and in turn, over their properties for further modulation and functionalization. The size-tunable nanoparticles were synthesized in a single step from different polymerization techniques such as dispersion and micro-emulsion with Glaser-Hay polymerization. The size of the resulting carbon nanoparticle is controlled by changing different reaction parameters such as the monomer loadings and the concentration. The control over the different parameters allows us to obtain monodisperse spherical CNPs with a size in the range of 25 nm to 250 nm and use of low temperature methods (<100 oC) allows us to overcome the limitations associated with current methods. After isolation, CNPs were characterized by dynamic light scattering, microscopy to analyze the shape and size of the CNPs. To analyze the nature of carbon molecules, Raman spectroscopy and FTIR were used. The optoelectronic behavior of the CNPs was characterized in order to establish the size-property relationships.

Hydrothermal synthesis of spherical carbon nanoparticles (CNPs) for supercapacitor electrodes uses

In this paper, hydrothermal method was used to provide stable colloidal suspension of spherical carbon nanoparticles (CNPs) with good uniformity of size and shape. XRD analyses showed the formation of crystalline structure of carbon material. CNPs Raman spectrum indicates the high quality with a low content of structural defects and high graphitic degree. The formation of CNPs is confirmed by an absorption peak at 264 nm. XPS technique showed well a significant decrease of oxygen-containing functional groups, indicating a low degree of graphite oxidation. The active surface area of CNPs was measured by BET technique. TEM images show that CNPs are nearly spherical in shape and the diameters varying between 50 and 120 nm. The CV behaviors showed that CNPs exhibit the higher specific capacitance values, and is greatly improved over that of previously reported carbon nanomaterials.

Development of an electrochemical sensor of endocrine disruptor bisphenol A by reduced graphene oxide for incorporation of spherical carbon nanoparticles

This work describes the synthesis of graphene oxide (GO) and its reduction using only carbon nanoparticles with no conventional chemical reducer or external energy. The reduced graphene oxide formed through the incorporation of the carbon nanoparticles (rGO-CNPS) was characterized by HR-TEM techniques, UV–vis, Raman spectroscopy and electrochemical techniques. The rGO-CNPS nanomaterial was incorporated on the surface of the printed carbon electrode and used to determine the endocrine interferent bisphenol A. The SPE-rGO-CNPS electrode presented excellent response for bisphenol A at concentrations varying from 7.5 × 10−9 to 2.6 × 10−7 mol L−1 in PBS, pH 7 with sensitivity 189.5 μmol L−1 and detection limit of 1 × 10−9 mol L−1. The electrode also presented excellent performance even in the presence of the main phenolic interferences and was used for determination of bisphenol A in plastic-bottled drinking water.

Controllable synthesis of carbon nanomaterials by direct current arc discharge from the inner wall of the chamber

A direct current (DC) has been applied to prepare many carbon nanomaterials, including fullerene, graphene, and carbon nanohorns (CNHs) from inner wall of chamber. However, the growth mechanism of these carbon nanomaterials is not clear. Amorphous spherical carbon nanoparticles (SCNs), the typical ‘dahlia-like’ CNHs, and graphene with the layer numbers of 2–5 were synthesized controllably from the inner wall of the chamber by DC arc discharge method using argon, nitrogen, and hydrogen as buffer gas. Simultaneously, the effect of buffer gas pressure on the morphology of carbon nanomaterials was investigated systematically. Furthermore, the formation mechanism of these carbon nanomaterials by DC arc discharge was also investigated. Given that argon atom was difficult to bond with the carbon cluster, the random bond between carbon clusters contributed to combine into amorphous SCNs; the CN bond was the key factor in the formation of CNHs, and hydrogen contributes to form graphene sheets by terminating carbon dangling bonds. With increasing the pressure of buffer gas, intense quenching resulted in formation of carbon nanomaterials with high purity. The study on the growth mechanism of carbon nanomaterials in the inner wall of chamber promotes the preparation of carbon nanomaterials controllable by arc discharge method.