Formation Of Carbon Nanoparticles Research Articles

Effects of different roasting temperatures on rabbit meat protein oxidation and fluorescent carbon nanoparticle formation

This study explores the oxidation of rabbit meat proteins and the physicochemical properties of the resulting fluorescent carbon nanoparticles (CNPs) under various roasting temperatures (180, 210, 240, 270, and 300 °C). The determination of sulfhydryl content, along with the results from UV and fluorescence spectroscopy, indicates that the protein structure undergoes changes during the roasting process, and the degree of oxidation shows an increasing trend with rising roasting temperatures. The CNP solution obtained exhibits a typical blue fluorescence. Moreover, as the roasting temperature increases from 180 °C to 300 °C, the relative content of the three elements in CNPs, namely C, N, and O, increases by 12 %, −3%, and −9 %, respectively. The surface of the obtained rabbit meat CNPs contains hydrophilic and polycyclic groups, such as carbonyl, hydroxyl, and amide bonds. Correlation analysis reveals a significant positive correlation between the degree of protein oxidation and the fluorescence intensities of CNPs.

Laser-Induced Graphene-based Flexible Substrate with Photothermal Conversion and Photoresponse Performance on Polyimide Film.

Graphene-based flexible electronic devices are widely used in photoelectric components and photodetectors. However, it remains a huge challenge to fabricate graphene-based flexible devices efficiently and economically. Compared with the flexible electronic devices made by combining the flexible film with metal and semiconductor materials, the graphene-based flexible substrate (GFS) can be efficiently and conveniently induced by laser direct writing on the flexible film. In this paper, the GFS with a resistance of as low as 15 Ω was successfully induced by CO2 laser on a polyimide (PI) film in one step, and the GFS surface covered with carbon nanoparticles (GFSC) with a resistance of 25 Ω was further induced by femtosecond (fs) laser reprocessing. Benefiting from the laser-induced porous graphene structure, the absorptivity of GFS is up to 90% in the wavelength range of 200-2000 nm. The formation of carbon nanoparticles on the GFSC surface further improves the absorptivity to 97.5% in a wide spectral range. Under white light irradiation of 1 sun, the surface temperature of GFS reaches 65.7 °C and that of GFSC is up to 70.8 °C within 2 min. Under the irradiation of a light-emitting diode (LED) with a central wavelength of 365 nm, the highest photoresponsivity of GFS and GFSC was 8.8 and 1.3 mA/W, respectively. The response time and recovery time of GFS are 8 and 7.3 s, and those of GFSC are 8.3 and 6.7 s, respectively. Importantly, GFSC has a more stable photoresponse performance due to the better electron capture and transfer capability of carbon nanoparticles. It is believed that GFS and GFSC have great application potential in flexible photodetectors and sensors.

Development of a Fully Reversible PAH Clustering Model

Physical clustering of Polycyclic Aromatic Hydrocarbon (PAH) molecules is subject to many studies as a part of understanding the complex clustering behavior and formation of carbon nanoparticles, such as soot and carbon black. A new fully reversible PAH clustering (FRPC) model is introduced to account for the full reversibility of PAH inception and molecular adsorption. Instead of assessing the performance of the new FRPC in a flame simulation as is typically done, a simplified system is utilized such that PAH clustering can be isolated from all other particle processes. The chosen simplified system consists of a 0D homogeneous reactor of PAHs at certain temperatures and has previously been investigated using molecular dynamics. The results from the FRPC model display excellent performance when compared to the molecular dynamic results. It is found that reversible rates play a significant role for smaller PAHs and at higher temperatures where the conditions are closer to an equilibrium between the gas-phase and condensed-phase PAHs. It is demonstrated that efficiency-based models are ill-suited to model PAH clustering due to the lack of explicitly modeling the reverse rates of clustering. The newly developed FRPC model represents the first step in a piece-wise development of a carbon nanoparticle formation model. ▪

Two-stage carbon condensation model during detonation of high explosives

During detonating of high explosives with a negative oxygen balance, one of the products of the chemical reaction is condensed carbon. However, the lack of experimental data does not allow us to give a quantitative assessment of the carbon condensation process today. In this paper, a two-stage model of carbon condensation during the detonation of high explosives is proposed. We used small-angle X-ray scattering method to study the dynamics of the formation of carbon nanoparticles during the detonation of charges of a mixture of TNT and RDX.

NanoParticle Flow Reactor (NanoPFR): a tested model for simulating carbon nanoparticle formation in flow reactors

Abstract Flow reactors are widely used to study the formation of various nanoparticles, such as carbon black, soot, nickel, titania, and silica. Such reactors provide well-controlled conditions, making them a favored laboratory tool to investigate the details of particle formation. Here we present NanoParticle Flow Reactor (NanoPFR), a detailed model to simulate nanoparticle synthesis in flow reactors. The model predicts the agglomerate fractal-like morphology and size distribution with a 2-variable sectional population balance model coupled with gas-phase chemistry. The particle formation processes employed in the code are tested using detailed discrete element modeling simulations and then used to predict carbon black formation from ethylene pyrolysis experiments from the literature. The code is a robust flow reactor predictive tool with a strong foundation that can serve as a basis for further development, including the simulation of other nanoparticles formation.

Molecular Simulation of the Formation of Carbon Nanoparticles

The formation of carbon nanoparticles is studied by molecular-dynamics simulation using the AIREBO model. It is shown that, upon simulation of the system at a temperature of 6000 K, finite size effects appear. At a temperature of 2000 K, the system forms clusters with a fairly high degree of graphitization.

The effect of radial diffusion on nanoparticle formation in laminar flow reactors

The present work examines two-dimensional effects during nanoparticle formation in laminar flow reactors using two approaches: a 2D model and a simplified 1D model. The investigated cases consist of carbon nanoparticle synthesis via ethylene pyrolysis in laminar flow. The simplified 1D simulations are conducted using the 1D plug flow solver Nano PFR, while the 2D simulations have been performed using CoFlame in an axisymmetric configuration. Both models utilize a sectional population balance model coupled with gas-phase chemistry to simulate detailed particle formation processes.The effects of radial diffusion of the 2D approach are analyzed in a reference case of an isothermal reactor by comparing a diffusion model against a no-diffusion model. Results show that radial diffusion sufficiently mixes the gas phase species along the radius to approximate plug flow. While radial diffusion effects are apparent in particle formation, it is not nearly enough to develop a uniform radial profile for the primary particle and agglomerate number densities and volume fraction. Next, experimental data from the literature are simulated, examining the suitability, differences, and limitations between the 1D and 2D domains. Both models perform similarly in prediction accuracy for the gas-phase species, including fuel pyrolysis and PAH formation. Moreover, by integrating particle mass across several regions (i.e. radial integration approach), the 1D model can achieve accuracy on par with the 2D model for particle formation predictions. Both models can adequately capture SMPS measurements for particle volume fraction, number densities, and size distributions. Ultimately, within the range of experimental conditions typically found in current laminar flow reactor studies for carbon nanoparticle formation, a modified 1D approach can sufficiently describe the gas-phase chemistry and particle formation processes with lower computational costs than the 2D approach.

Pressure-Dependent Tuning of Photoluminescence and Size Distribution of Carbon Nanodots for Theranostic Anticancer Applications.

Carbon nanodots (CDs) have recently attracted attention in the field of nanomedicine because of the biocompatibility, cost-effective nature, high specific surface, good near infrared (NIR) photothermal conversion into heat and tunable fluorescence properties, which have paved the way toward incorporating use of CDs into innovative anticancer theranostic platforms. However, a reliable synthesis of CDs with established and controlled physiochemical proprieties is precluded owing to the lack of full manipulation of thermodynamic parameters during the synthesis, thus limiting their use in real world medical applications. Herein, we developed a robust solvothermal protocol which allow fine controlling of temperature and pressure in order to obtain CDs with tunable properties. We obtained different CDs by modulating the operating pressure (from 8 to 18.5 bar) during the solvothermal decomposition of urea and citric acid in N,N-dimethylformamide at fixed composition. Atomic force microscopy (AFM), Fourier transform infrared (FTIR), ultraviolet-visible (UV-vis) and fluorescence spectroscopy were used to assess the role of pressure in influencing size, optical and surface properties of the obtained CDs. While preliminary biological and anticancer performance of CDs was established on the MDA-MB-231 cell line, used as triple negative breast cancer model. Our results indicate that pressure impinge on the formation of carbon nanoparticles under solvothermal conditions and impart desired optical, size distribution, surface functionalization and anticancer properties in a facile way. However, we have highlighted that a strategic surface engineering of these CDs is needed to limit the adsorption of corona proteins and also to increase the average surface diameter, avoiding a rapid renal clearance and improving their therapeutic efficacy in vivo.

High temperature pure carbon nanoparticle formation: Validation of AIREBO and ReaxFF reactive molecular dynamics

Molecular dynamics with reactive interatomic potentials is the only computationally feasible approach for modeling at the atomistic level the formation of carbon nanoparticles from gas state. Such models require thousands of atoms and millions of time steps that is beyond the current capabilities of first principles electronic structure calculations. A continuously growing variety of available reactive interatomic potentials for carbon requires their careful validation for a particular molecular system and pressure-temperature conditions. In this work we consider a generic example process of carbon nanoparticle formation at cooling of the gas phase and compare different AIREBO and ReaxFF reactive models. Three main processes of clusterization, change of hybridization and graphitization are analysed and used for comparison of potentials. Ab initio density functional theory and parameterized density functional tight-binding calculations together with experimental data available are used for validation of the reactive models considered. We highlight the detected problems of some well-known reactive potentials and conclude with three models that can be selected as the best options for molecular dynamics simulations of pure carbon nanoparticle formation.

Scalable preparation of carbon nanoparticles and graphene nanoflakes using sand paper abrasion

AbstractThe commercial demand for carbon nanoparticles and graphene nanoflakes are high due to their diverse usage over the past few years. However, large scale production processes are quite laborious and time consuming relying mainly on high energy and inert atmospheric condition. Herein, the abrasion technique has been utilized to exfoliate carbon nanoparticles and graphene nanoflakes from willow charcoal stick and graphite rod, respectively. The role of sandpaper in polishing is quite immense for the isolation of nanocarbons from willow charcoal and graphite. Transmission electron microscope (TEM) confirmed the formation of carbon nanoparticles whereas, high resolution transmission electron microscope (HRTEM) and atomic force microscope (AFM) topography revealed the formation of few layers of graphene nanoflakes. This entire green process was economically viable for scalable preparation of nanocarbons at room temperature and completely independent of inert conditions, usage of solvents, chemicals and the problem of by‐product formation.))

Temperature dependence of iron oxide-graphene oxide properties for synthesis of carbon nanotube/graphene hybrid material

Iron oxide embedded on graphene oxide (Fe2O3/GO) was prepared by chemical exfoliation followed by wet impregnation. Reduced Fe2O3/GO could be employed as catalyst for synthesizing carbon nanotubes CNTs via catalytic chemical vapor deposition CCVD of n-hexane within a temperature range of 700-1000 °C. It was found that during the synthesis process, pretreatment affected the transformation of iron nanoparticles in the Fe2O3/GO, leading to significant difference in formation of carbon nanoparticles. When the Fe2O3/GO was employed within a temperature range of 700−900 °C, Fe2O3 was reduced to α-Fe, yielding CNT growth on the graphene surface. However, the α-Fe could be transformed to γ-Fe when the Fe2O3/GO was subject to the temperature of 1000 °C, resulting in formation of carbon spheres instead of CNTs. After experimentally verified, conceptual scenarios of CNT/graphene hybrid material formation with respect to the pretreatment and synthesis temperature were proposed and discussed.

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.

Pyrolysis of a mixture of monosilane and alkanes in a compression reactor to produce nanodispersed silicon carbide

The method of producing of nano-dimensional silicon carbide by compressing in a cyclic chemical reactor is proposed. Pyrolysis is initiated in mixtures of monosilane and hydrocarbon with argon. The resulting product is examined by X-ray diffraction and electron microscopy. It is established that the powder contains crystallites of silicon carbide with an average size of 5–12 nm. It is shown that at certain ratios of precursor concentrations in argon, the formation of carbon nanoparticles and/or graphene coating on the surface of SiC particles is also possible. The method is technological and efficient, it can be used in the production of high purity silicon carbide nanopowders and other compounds.

Reactive molecular-dynamics study of onion-like carbon nanoparticle formation

Formation of carbon nanoparticles is an important type of complex non-equilibrium processes that require precise atomistic theoretical understanding. In this work, we consider the process of ultrafast cooling of pure carbon gas that results in nucleation of an onion-like fullerene. The model is based on molecular dynamics simulation with the interaction between carbon atoms described via a reactive ReaxFF model. We study the consecutive stages of fullerene-like nanoparticle formation and identify the corresponding temperature ranges. Analysis of hybridization and graphitization reveals the underlying microscopic mechanisms connected with rearrangements of dihedral angles and density changes.

Flexoelectricity and the Formation of Carbon Nanoparticles in Flames

The formation of carbon nanoparticles in flames involves a nucleation step that remains poorly understood. Experimentally, carbon nuclei formation is known to depend strongly on the electrical aspects of combustion, but modes of interaction between charged species in the flame and carbon precursors have yet to be found. We present evidence for flexoelectrically polarized aromatics contributing to carbon nanoparticulate nucleation. We imaged the nascent nanoparticles using high resolution transmission electron microscopy, which revealed that the majority of aromatics in the early carbon nanoparticles are fullerene-like and curved. The curvature induces a significant molecular flexoelectric dipole moment in the polyaromatic hydrocarbons. This electric polarization allows these molecules to strongly interact with chemi-ions produced during combustion, which we demonstrate using electronic structure calculations. The results indicate that the physical interaction between fullerene-like polar aromatics and chemi-ions is critically assisting the nucleation and opens a new route to reduce pollution and improve flame-produced nanomaterials.

Flame deposition method for carbon nanoparticles employing green precursors and its composite with Au nanoparticles for photocatalytic degradation of methylene blue

Present article describes green synthesis of carbon nanoparticles (CNPs) with signature of graphene oxide using different organic precursors such as, almond flames, mustard oil, clarified butter (Indian ghee) and burnt almond residue (char). The presence of high percentage of carbon content in saturated fatty acids prompted the current research. The flames of these organic precursors lead to the deposition of self-assembled CNPs on a metallic substrate. The CNPs were characterized by UV-Visible, Raman spectroscopy, particle size analysis, XRD, SEM and TEM. UV-Visible spectroscopy showed absorbance of CNPs in the visible region. The formation of CNPs was confirmed from XRD analysis. The spherical shape and self-assembly of CNPs was observed from TEM images for all the samples. The CNPs were combined with gold NPs by chemical reduction method using hydrazine hydrate as reducing agent. CNPs and Au/C NPs were employed as photo-catalyst for degradation of the methylene blue (MB) under long UV as well as natural sunlight. The degradation of MB was studied by the first order of kinetics.

Optimized synthesis and characterization of lutetium carbonate and oxide nanoparticles and their use as degradation photocatalyst

Taguchi robust design (TRD) was used to optimize the process for fabrication lutetium carbonate which was then used for the synthesis of lutetium oxide nano-particles, which were subjected to characterization analyses. Through TRD the significance of variables including the concentrations of lutetium and carbonate ion solutions, and the flow rate at which one reagent was added to the other (Fy), and the reactor temperature during the formation of the carbonate particles in the chemical precipitation stage were evaluated. The optimum conditions were found to lead to the formation of carbonate nano-particles with average diameter of 35 nm, which were then thermally treated at 750 °C in an air atmosphere, to form spherical lutetium oxide (Lu2O3) nanoparticles of about 36 nm in average diameter. The produced nanoparticles were studied through SEM, TEM, XRD and FT-IR to evaluate their characteristics, and they were also evaluated as photocatalysts in the UV-induced degradation of methyl orange (MO) in an aqueous media.

Precipitation of dichloromethane as low-chlorine carbon nanoparticles from water by femtosecond laser pulses

Abstract We report on the transformation of dichloromethane to low-chlorine carbon nanoparticles by the exposure of aqueous dichloromethane solution and/or dichloromethane/water biphasic solution to femtosecond laser pulses. The pH of either solution immediately decreased due to the reduction of dichloromethane by hydrated electrons. The time evolution of transmittance revealed that particle formation was suppressed when the initial pH was low because protons scavenge hydrated electrons. The size and morphology of nanoparticles was independent of the initial pH and the reaction solution used. The analysis of the elemental composition of carbon particles showed that the Cl/C atomic ratio was, independent on the initial pH values, greatly reduced to 0.06. We propose that the violent destruction of dichloromethane and elimination of chlorine atoms not only as Cl − but also Cl 2 excludes chlorine atoms from the carbon network construction processes toward the formation of carbon nanoparticles.

Spectral and structural properties of carbon nanoparticles synthesized in natural and anthropogenic processes

In this contribution, we considered the character of carbon nanoparticle formation in the cosmos and during volcanic eruptions of a certain type and compared it with existing methods of synthesis in nanotechnology. Using the methods of electron diffraction and Raman spectroscopy, we investigated nanodiamond samples synthesized by hydrodynamic cavitation in various hydrocarbon liquids. Different forms of nanometer-sized carbon were distinguished, including complex fullerenes, nanodiamonds, and a face-centered cubic (fcc) carbon phase. The synthesized nanodiamonds were doped with silicon, their photoluminescence spectra were analyzed, and application of the results for geochemistry and cosmochemistry were discussed.

In English

Fractal structures are common in nature, and the structures that play a role in the formation of macroscopic systems, as well as represent new structures characterized by dramatic changes in the physical properties. The aim of this work is to determine the dimensions of fractal carbon structures using electron microscopy and provision characteristics of fractal carbon structures by calculating the fractal dimension. The feedstock for fractal structures in an arc discharge is a mixture of pyrolytic carbon and coal tar. The fractal carbon structures has been systematically studied by scanning electron microscopy (SEM) and transmission electron microscopy. The SEM observation shows quite a large range of sizes of fractal clusters and aggregates. The TEM analysis reveals formation of carbon nanoparticles in a narrow range of 2–8 nm. The results show that the fractal structure of the carbon deposits are volumetric fractals with dimension of carbon deposits of 2.96. Volume fractal structure consisting of fractal aggregates, the cloud formations, and the like ones having a similar structure may be formed of different materials - graphite and pyrolytic carbon. A necessary condition for the nucleation of carbon nanostructures is the formation of carbon nanoparticles in an arc discharge.