Types Of Carbon Nanoparticles Research Articles

Electrochemical detection of anti-tissue transglutaminase antibody using quantum dots-doped polypyrrole-modified electrode

A nanohybrid-modified glassy carbon electrode based on conducting polypyrrole doped with carbon quantum dots (QDs) was developed and used for the electrochemical detection of anti-tissue transglutaminase (anti-tTG) antibodies. To improve the polypyrrole conductivity, carrier mobility, and carrier concentration, four types of carbon nanoparticles were tested. Furthermore, a polypyrrole-modified electrode doped with QDs was functionalized with a PAMAM dendrimer and transglutaminase 2 protein by cross-linking with N-hydroxysuccinimide (NHS)/N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC). The steps of electrode surface modification were surveyed via electrochemical measurements (differential pulse voltammetry (DPV), impedance spectroscopy, and X-ray photoelectron spectroscopy (XPS)). The surface characteristics were observed by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and contact angle measurements. The obtained modified electrode exhibited good stability and repeatability. DPV between − 0.1 and 0.6 V (vs. Ag/AgCl 3 M KCl reference electrode) was used to evaluate the electrochemical alterations that occur after the antibody interacts with the antigen (transglutaminase 2 protein), for which the limit of detection was 0.79 U/mL. Without the use of a secondary label, (anti-tTG) antibodies may be detected at low concentrations because of these modified electrode features.Graphical

Impact of conjugated polymer addition on the properties of paraffin-asphaltene blends for heat storage applications: Insight from computer modeling and experiment.

Adding carbon nanoparticles into organic phase change materials (PCMs) such as paraffin is a common way to enhance their thermal conductivity and to improve the efficiency of heat storage devices. However, the sedimentation stability of such blends can be low due to aggregation of aromatic carbon nanoparticles in the aliphatic paraffin environment. In this paper, we explore whether this important issue can be resolved by the introduction of a polymer agent such as poly(3-hexylthiophene) (P3HT) into the paraffin-nanoparticle blends: P3HT could ensure the compatibility of aromatic carbon nanoparticles with aliphatic paraffin chains. We employed a combination of experimental and computational approaches to determine the impact of P3HT addition on the properties of organic PCMs composed of paraffin and carbon nanoparticles (asphaltenes). Our findings clearly show an increase in the sedimentation stability of paraffin-asphaltene blends, when P3HT is added, through a decrease in average size of asphaltene aggregates as well as in an increase of the blends' viscosity. We also witness the appearance of the yield strength and gel-like behavior of the mixtures. At the same time, the presence of P3HT in the blends has almost no effect on their thermophysical properties. This implies that all properties of the blends, which are critical for heat storage applications, are well preserved. Thus, we demonstrated that adding polyalkylthiophenes to paraffin-asphaltene mixtures led to significant improvement in the performance characteristics of these systems. Therefore, the polymer additives can serve as promising compatibilizers for organic PCMs composed of paraffins and asphaltenes and other types of carbon nanoparticles.

An Investigation on Nano-Enhanced Phase Change Materials: Carbon-Based Nanoparticles

The current research presents an overview of four types of carbon nanoparticles that are: carbon black nano powder, multi-walled carbon nanotube, graphene, and graphite. The aim of this paper is to show the importance of carbon-based nano-enhanced phase change materials (NEPCM). The effect of using different types of nanoparticles at various loading concentrations has been examined. It was found that the effective thermal conductivity can be enhanced by increasing the nanoparticles loading concentration regardless of NEPCM type. However, this may be accompanied by a slower melting process which also depends on the nanoparticle’s density. Thus, the duration of storage is reported as a crucial factor to check the feasibility of using such nanoparticles. The highest reported thermal conductivity enhancement is ~300% considering CaCl2.6H2O as a phase change material with 30 wt.% multi-walled carbon nanotube.

Reproductive and Developmental Nanotoxicity of Carbon Nanoparticles.

The presented review aims to summarize the knowledge regarding the reproductive and developmental toxicity of different types of carbon nanoparticles, such as graphene, graphene oxide, multi- and single-walled nanotubes, fullerenes, and nanodiamonds. Carbon nanoparticles have unique chemical and physical properties that make them an excellent material that can be applied in many fields of human activity, including industry, food processing, the pharmaceutical industry, or medicine. Although it has a high degree of biocompatibility, possible toxic effects on different tissue types must also be taken into account. Carbon nanoparticles are known to be toxic to the respiratory, cardiovascular, nervous, digestive system, etc., and, according to current studies, they also have a negative effect on reproduction and offspring development.

High-Temperature Oxidation of Single Carbon Nanoparticles: Dependence on the Surface Structure and Probing Real-Time Structural Evolution via Kinetics.

O2 oxidation and sublimation kinetics for >30 individual nanoparticles (NPs) of five different feedstocks (graphite, graphene oxide, carbon black, diamond, and nano-onion) were measured using single-NP mass spectrometry at temperatures (TNP) in the 1100-2900 K range. It was found that oxidation, studied in the 1200-1600 K range, is highly sensitive to the NP surface structure, with etching efficiencies (EEO2) varying by up to 4 orders of magnitude, whereas sublimation rates, significant only for TNP ≥ ∼1700 K, varied by only a factor of ∼3. Its sensitivity to the NP surface structure makes O2 etching a good real-time structure probe, which was used to follow the evolution of the NP surface structures over time as they were either etched or annealed at high TNP. All types of carbon NPs were found to have initial EEO2 values in the range near 10-3 Da/O2 collision, and all eventually evolved to become essentially inert to O2 (EEO2 < 10-6 Da/O2 collision); however, the dependence of EEO2 on time and mass loss was very different for NPs from different feedstocks. For example, diamond NPs evolved rapidly and monotonically toward inertness, and evolution occurred in both oxidizing and inert atmospheres. In contrast, graphite NPs evolved only under oxidizing conditions and were etched with complex time dependence, with multiple waves of fast but non-monotonic etching separated by periods of near-inertness. Possible mechanisms to account for the complex etching behavior are proposed.

Thermophoresis of carbon nanoparticles (nanoribbons and nanotubes) on a flat multilayer substrate of hexagonal boron nitride (h-BN)

Using the method of molecular dynamics and a 2D chain model, it is shown that thermophoresis of carbon nanoparticles (nanoribbons and nanotubes) on a flat multilayer substrate (on a flat surface of a hexagonal boron nitride crystal) has high efficiency. Placing a nanoparticle on a flat surface of a substrate involved in heat transfer leads to its movement in the direction of the heat flow. The heat flow along the substrate leads to the formation of constant forces acting on the nanoparticle nodes (thermophoresis forces). The main effect of the force is exerted on the edges of graphene nanoribbons, exactly where the main interaction of the nanoribbon with the bending phonons of the substrate occurs. These phonons have a long free path, so the effective transfer of nanoparticles using thermophoresis can occur at sufficiently large distances. The motion of carbon nanoparticles under the action of a heat flow has the form of particle motion in a viscous medium under the action of a constant force. Over time, the nanoparticles always enter the mode of movement at a constant speed. The velocity of the stationary motion is almost the same for all sizes and types of carbon nanoparticles, which is explained by the fact that the thermophoresis force and effective friction have the same source --- the interaction of the nanoparticle with the bending thermal vibrations of the substrate layers. Keywords: nanoribbons, nanotubes, flat multilayer substrates, thermophoresis, 2D model of the multilayer substrate.

AN ANALYSIS OF THE INFLUENCE OF CARBON NANOPARTICLES ADDITIVE ON SELECTED PROPERTIES OF LUBRICATING OILS

This paper presents the results of an analysis of the influence of the addition of various types of carbon nanoparticles on selected essential physical and operational properties of lubricating oils. Two selected oils, i.e. the mineral base oil without additives and the typical marine lubricating circulating oil Marinol RG 1240, were modified with the addition of shungite nanoparticles, graphite nanotubes, and C60 fullerenes. The mass fraction of modifiers was 0.2% wt for each of the additives. As part of the experimental tests, measurements were made of the impact of the above-mentioned modifiers on the change in the value of the ignition temperature of oils, the effect on the changes in the value of the dynamic viscosity coefficient in the aspect of changes of temperature and shear rate, as well as the impact on the changes in the friction coefficient and the size of the wear size scar. These tests were carried out on an EraFlash automatic apparatus for determining ignition temperature using the closed cup method, with a Haake Mars III research rheometer, and a T-02U tribometer with a four-ball head.

Study of peritectic compound Li4(OH)3Br for high temperature thermal energy storage in solar power applications

This paper focus on the study of peritectic compound Li4(OH)3Br for thermal energy storage in solar power applications. A thoroughly characterization of Li4(OH)3Br as storage material has been performed by measuring transition temperatures (280–289 °C), enthalpies of transition (247 J/g), specific heats (c.a. 1.68 J/g/K in solid, 2.52 J/g/K in liquid) and thermal conductivity (0.47 W/m/K at room temperature). The effect of the synthesis conditions on the storage properties has been investigated as well. It is concluded that neither the cooling rate applied during the synthesis stage nor the type of atmosphere used (ambient air and protective argon atmosphere) has an influence on the material's performance. The stability of the material to thermal cycling has also been analysed, showing good cycling stability. Moreover, particular attention is paid to the elucidation of mechanisms of formation of Li4(OH)3Br. It is shown that Li4(OH)3Br needs neither the presence nor contact with the pro-peritectic phase to form. It nucleates and grows directly from the melt so as pure-phase Li4(OH)3Br final microstructure is achieved. An attempt to enhance the storage capacity of the material by addition of different types of carbon nanoparticles has been carried out. Assets of Li4(OH)3Br as storage materials for high-pressure DSG solar power plants have been assessed through comparison with reference material NaNO3. Main advantages of Li4(OH)3Br are higher volumetric latent heat storage capacity (+54%) and lower volume changes during phase transitions (3% vs. 11%), which would translate into smaller storage tanks (−33%), lower size heat exchangers and longer lifetime.

Probing nano-QSAR to assess the interactions between carbon nanoparticles and a SARS-CoV-2 RNA fragment

The coronavirus disease-19 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is rampant in the world and is a serious threat to global health. The SARS-CoV-2 RNA has been detected in various environmental media, which speeds up the pace of the virus becoming a global biological pollutant. Because many engineered nanomaterials (ENMs) are capable of inducing anti-microbial activity, ENMs provide excellent solutions to overcome the virus pandemic, for instance by application as protective coatings, biosensors, or nano-agents. To tackle some mechanistic issues related to the impact of ENMs on SARS-CoV-2, we investigated the molecular interactions between carbon nanoparticles (CNPs) and a SARS-CoV-2 RNA fragment (i.e., a model molecule of frameshift stimulation element from the SARS-CoV-2 RNA genome) using molecular mechanics simulations. The interaction affinity between the CNPs and the SARS-CoV-2 RNA fragment increased in the order of fullerenes < graphenes < carbon nanotubes. Furthermore, we developed quantitative structure–activity relationship (QSAR) models to describe the interactions of 17 different types of CNPs from three dimensions with the SARS-CoV-2 RNA fragment. The QSAR models on the interaction energies of CNPs with the SARS-CoV-2 RNA fragment show high goodness-of-fit and robustness. Molecular weight, surface area, and the sum of degrees of every carbon atom were found to be the primary structural descriptors of CNPs determining the interactions. Our research not only offers a theoretical insight into the adsorption/separation and inactivation of SARS-CoV-2, but also allows to design novel ENMs which act efficiently on the genetic material RNA of SARS-CoV-2. This contributes to minimizing the challenge of time-consuming and labor-intensive virus experiments under high risk of infection, whilst meeting our precautionary demand for options to handle any new versions of the coronavirus that might emerge in the future.

Study on formation mechanism of three types of carbon nanoparticles during ethylene pyrolysis in thermal plasmas

Products of three carbon phases were synthesized by the pyrolysis of ethylene using a magnetically rotating arc under atmospheric pressure; the products thus produced were graphene nanoflakes, semi-graphite particles, and carbon nanospheres. The effects of temperature, buffer gas flow and gas type (H2 and CO2), and high temperature residence time on the morphology of the products were investigated. The results revealed that a higher temperature, proper H2 and CO2 flow, and a shorter residence time are favorable for the production of graphene with fewer layers, fewer defects, and higher purity. A suitable H/C ratio and the formation of macromolecular carbonaceous clusters are essential factors for the synthesis of semi-graphite particles. The overgrowth of graphene and the aggregation of small molecules of PAHs in the low temperature region are favorable for the formation of carbon nanospheres.

Role of different dimensional carbon nanoparticles in catalytic oxidation of organic pollutants and alleviating membrane fouling during ultrafiltration of surface water

• Different types of carbon nanoparticles (CNPs) were used for catalytic oxidation. • CNPs/peroxymonosulfate (PMS) were proposed for membrane fouling control. • The catalytic activity of PMS showed the order of CMK-3 > CNTs > CMK-8 > CNFs. • SO 4 − , OH, O 2 − and 1 O 2 were identified as the main reactive oxygen species. • The formation of cake layers on membrane surfaces was delayed. In this study, carbon nanoparticles (CNPs) in different structural dimensions, including carbon nanotubes (CNTs), carbon nanofibers (CNFs), hexagonally (CMK-3) and cubically (CMK-8) ordered mesoporous carbons were proposed for peroxymonosulfate (PMS) activation. The performance for catalytic oxidation of organic pollutants and alleviating ultrafiltration membrane fouling was systematically investigated and compared. The results showed that CMK-3 performed best for PMS activation in the reduction of typical micropollutants and natural organic matter, whereas the efficiency of CNFs was relatively limited. The CNPs/PMS processes were efficient alternatives for alleviating membrane fouling, whereas discrepancies existed in the performance for different CNPs. Both the decomposition of macromolecular biopolymers and the degradation of fluorescent components reduced the foulants directly contacting with membranes, thus contributing to the fouling mitigation. The characterization of fouled membranes (i.e., surface morphologies and functional groups) further verified the fouling alleviation. From a comparison view, the decomposition of PMS by CMK-3 was more effective compared to the other CNPs, with the catalytic capacity of CMK-3 > CNTs > CMK-8 > CNFs. The discrepancy was likely ascribed to the microstructure differences of carbonaceous materials. To be specific, CNTs exhibited a curled-like shape with smaller diameter and larger specific surface area than CNFs, while CMK-3 showed long straight and parallel channels with decreased internal resistances than CMK-8. The electron paramagnetic resonance analyses revealed that SO 4 − , OH, O 2 − and 1 O 2 were the main reactive oxygen species generated in the systems. The CNPs/PMS processes significantly changed the fouling mechanisms by delaying the formation of cake layers and prolonging the transition volumes. These findings possess a guiding significance for the application of carbon-based catalytic oxidation in membrane water treatment processes.

Термофорез углеродных наночастиц (нанолент и нанотрубок) на плоской многослойной подложке гексагонального нитрида бора (h-BN)

Using the method of molecular dynamics and a 2D chain model, it is shown that thermophoresis of carbon nanoparticles (nanoribbons and nanotubes) on a flat multilayer substrate (on a flat surface of a hexagonal boron nitride crystal) has high efficiency. Placing a nanoparticle on a flat surface of a substrate involved in heat transfer leads to its movement in the direction of the heat flow. The heat flow along the substrate leads to the formation of constant forces acting on the nanoparticle nodes (thermophoresis forces). The main effect of the force is exerted on the edges of graphene nanoribbons, exactly where the main interaction of the nanoribbon with the bending phonons of the substrate occurs. These phonons have a long free path, so the effective transfer of nanoparticles using thermophoresis can occur at sufficiently large distances. The motion of carbon nanoparticles under the action of a heat flow has the form of particle motion in a viscous medium under the action of a constant force. Over time, the nanoparticles always enter the mode of movement at a constant speed. The velocity of the stationary motion is almost the same for all sizes and types of carbon nanoparticles, which is explained by the fact that the thermophoresis force and effective friction have the same source – the interaction of the nanoparticle with the bending thermal vibrations of the substrate layers.

The Investigation of the Dependence of Optical, Luminescent, and Emission Properties of Carbon Nanoparticles on pH of the Medium

The effect of pH of the medium on the optical, luminescent, and emission parameters of various types of carbon nanoparticles (CNPs) in aqueous solutions is studied. It is shown that the parameters of the optical absorption and photoluminescence spectra, as well as the value and stability of the quantum yield of emission, significantly depend on the value of pH of the medium and the properties of the functional groups and carbon cores of the carbon nanoparticles. The main contribution to the change in the specified parameters of carbon nanoparticles is made by their functional groups. The strongest and most vivid change in the optical and luminescent parameters of all the types of carbon nanoparticles is observed in the ranges of pH of an aqueous solution of 10–13 and 0.1–3. The change in the parameters of carbon nanoparticles is closely related to the processes of protonation and deprotonation of the functional groups of the particles of the CNPs–COOH, CNPs–OH, and CNPs–NH2 types as well as to photostimulated processes. A growth and a decline in the absorption and emission, appearance and disappearance of absorption bands, change in the symmetry and width of the contours, and also the bathochromic and hypsochromic shifts of the absorption and photoluminescence bands are often observed in the absorption and photoluminescence spectra with the change in pH of the medium of carbon nanoparticles. It is shown that the mechanism of the effect of nitrogen and oxygen heteroatoms of the functional groups on the photoluminescence and quantum yield of emission is associated with the complex interactions of the electrons of the unshared pairs of the N and O atoms with the π-system of the aromatic rings of the carbon core of the nanoparticles.

Quantification of the Effects of Strain Rate and Nano-Reinforcement on the Performance of Adhesively Bonded Single-Lap Joints

The aim of this study is to present an efficient and effective technique to strategically investigate and classify the influence of a set of manipulated parameters that affect the mechanical properties and performance of adhesively bonded joints formed by an adhesive that is reinforced by various types of carbon nanoparticles (NPs). Specifically, single-lap joints (SLJs) are considered in this study. The selected parameters include the adherend types (i.e., carbon fiber-reinforced polymers (CFRPs) and glass fiber-reinforced polymers (GFRPs)), three types of nanoparticles (i.e., carbon nanofibers (CNFs), multi-walled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs)), different weight-percent (wt.%) of GNPs (i.e., 0, 0.5, 1%), and three different strain (or loading) rates, classified as static, quasi-static and impact loadings, herein. The study employed two mixed-level full factorial design of experiments (DOE) to evaluate the contribution of the aforementioned parameters, including the effect of their interactions on the enhancement of the averaged ultimate shear strength (AUSS) of the SLJs. The DOE study was conducted using the strength data (AUSS) obtained through testing of 108 SLJ specimens. The results indicate that among the considered parameters, NPs (wt%), adherend type, and strain rate had a greater effect on AUSS. According to the DOE conducted in this study, the greatest AUSS (19.9 MPa) could be obtained when 1.0 wt% GNP was used to reinforce the SLJs with CFRP adherend and subjected to the highest strain rate (HSR). This combination yielded a 32% enhanced AUSS compared to the SLJs formed by the neat adhesive.

Polycation-Carbon Nanohybrids with Superior Rough Hollow Morphology for the NIR-II Responsive Multimodal Therapy.

Polymer-inorganic hybrid nanomaterials have attracted much attention for the multimodal cancer therapy, while it is still desirable to explore hybrids with superior morphologies for two or more therapeutic modalities. In this work, four types of carbon nanoparticles with distinct morphologies were prepared by an elaborate template-carbonization corrosion process and then functionalized with a similar amount of the superior polycationic gene vector, CD-PGEA [consisting of one β-cyclodextrin core (CD) and two cationic ethanolamine-functionalized poly(glycidyl methacrylate) (PGEA) arms] to evaluate the morphology-influenced gene and photothermal (PT) therapy. Benefiting from the starting rough hollow nanosphere (RHNS) core, the resultant nanohybrids RHNS-PGEA exhibited the highest gene transfection (including luciferase, fluorescent protein plasmid, and antioncogene p53) and NIR PT conversion efficiency among the four types of nanohybrids. Moreover, the efficient PT effect endowed RHNS-PGEA with PA imaging enhancement and an effective imaging guide for the tumor therapy. In addition, anticancer drug 10-hydroxy camptothecin was successfully encapsulated in RHNS with polycation coating, which also displayed the second near-infrared (NIR-II)-responsive drug release. Taking advantages of the superior gene delivery/PT effect and NIR-II-enhanced drug delivery, RHNS-PGEA realized a remarkable therapeutic effect of trimodal gene/PT/chemotherapy of malignant breast cancer treatment in vitro and in vivo. The present work offers a promising approach for the rational design of polymer-inorganic nanohybrids with superior morphology for the multimodal cancer therapy.

Performance comparison with different methods for ethanol/O2 biofuel cell based on NAD+ cofactor immobilized and activated by two types of carbon nanoparticles

Biofuel cells are an attractive alternative to conventional fuel cells, because they use biological catalysts. We report in this article the construction of an ethanol/O2 enzymatic biofuel cell. In the first time, the performance comparison with different methods for ethanol/O2 biofuel cell has been study. Alcohol dehydrogenase, a nicotinamide adenine dinucleotide (NAD)-dependent enzyme, is immobilized with NAD+, diaphorase, and vitamin K3 (VK3) on the electrode. The oxygen is reduced at the cathode with laccase and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS). The performances of the electrodes are improved thanks to addition of carbon powder (KS6 and Super P® carbon). The benefit of the carbon particles with higher surface porosity was explained by the high-porous structure that offered a closer proximity to the reactive species and improved diffusion of ethanol and oxygen within the enzyme films. Efficiency of immobilization of NAD+ cofactor has been also demonstrated. We have shown the effect of multi-enzymatic reaction at the anode on the storage and operational stability. A high open-circuit potential has been recorded 1.02 V, demonstrating the benefit of NAD+ immobilization with maximal power density of 300 μW cm−2. Chronoamperometric measurements show a current density of 90 μA cm−2 during 20 h demonstrating the operational stability of the ethanol biofuel cell based on NAD+ cofactor immobilization.

Recent advancements in the applications of carbon nanodots: exploring the rising star of nanotechnology.

Nanoparticles possess fascinating properties and applications, and there has been increasing critical consideration of their use. Because carbon is a component with immaterial cytotoxicity and extensive biocompatibility with different components, carbon nanomaterials have a wide scope of potential uses. Carbon nanodots are a type of carbon nanoparticle that is increasingly being researched because of their astounding properties such as extraordinary luminescence, simplicity of amalgamation and surface functionalization, and biocompatibility. Because of these properties, carbon nanodots can be used as material sensors, as indicators in fluorescent tests, and as nanomaterials for biomedical applications. In this review, we report on the ongoing and noteworthy utilization of carbon quantum dots such as bioimaging tests and photocatalytic applications. In addition, the extension and future components of these materials, which can be investigated for new potential applications, are discussed.

Anomalous water diffusion in epoxy/carbon nanoparticle composites

Water absorption-desorption-resorption and swelling were studied for a DGEBA-based amine-cured epoxy resin filled with four types of carbon nanoparticles: multiwall carbon nanotubes (MWCNT), graphite nano-platelets (GnP), expanded graphite platelets, and carbon black. Nanocomposites are characterised by lower diffusivity (down to 20% for epoxy/GnP) and increased water sorption capacity compared to the neat epoxy. Anomalous water absorption and swelling of nanocomposites is finely described by the diffusion-relaxation model. The relaxation times, considered as quantitative indicators of changes in segmental mobility of the polymer, increased with addition of nanoparticles and decreased with temperature. Epoxy/MWCNT composites are characterised by the longest relaxation times (twofold increase) and highest Deborah numbers compared to the neat epoxy and other nanocomposites. Hydrothermal ageing effects and efficiency of nanoparticles on thermal and thermomechanical properties of the epoxy were estimated. Water uptake in nanocomposites is accompanied by several competing processes: plasticization, after-cure, and physical ageing of the polymer matrix.

Исследование оптических и люминесцентных свойств углеродных наночастиц методом микрофотолюминесценции

The important features of the optical, luminescent, and emission properties of aqueous solutions of carbon nanoparticles (CNPs) of various types in the interaction of particles with electromagnetic radiation have been studied and analyzed. It is shown that the functional groups of CNPs play the dominant role in the spectra of optical absorption and photoluminescence (PL) of particles. Hydrothermal (HT) treatment of CNPs in the presence of ammonia and thermal treatment of particles in a solution of hydrogen peroxide have a strong influence on the absorption spectra, PL, and quantum yield (QY) of emission. It was found that the main PL bands of CNP samples are formed by superposition of several separate PL bands associated with electronic transitions of various types of radiative centers, and their excited states are located in the band gap of the carbon core of the particles. It was established that this circumstance is the reason for the dependence of the position of the PL band peak of most types of CNPs on the excitation wavelength. Linear dependences of the position of the PL band maximum and the emission QY magnitude on temperature and an exponential dependence on the time of HT treatment were revealed. The method of exposure to exciting radiation showed that the change in the PL intensity and the emission QY value under the influence of electromagnetic radiation is due to the photostimulated change in the surface recombination rate and diffuse particle processes in the region of excitation of CNP solutions. The possibility of investigating the stability of PL and QY by exposure of CNPs solutions to excitation radiation was demonstrated.

Carbon Nano-Onions Synthesized By Laser Pyrolysis As Catalyst Support in Proton Exchange Membrane Fuel Cells

Proton exchange membrane fuel cells (PEMFC) typically utilize nanostructured carbon (such as carbon black, carbon nanotubes, graphene and porous carbon) as the support material for catalysts. The durability and electrical conductivity of the material are important contributors to the fuel cell performance, as well as the structural design to maximize the triple phase boundary between the fuel, the catalyst and the electrolyte membrane. In view of engineering the structure and composition of the carbon catalyst support, a versatile manufacturing method with flexibility in size, shape, structure, and properties (such as electrical conductivity) of the carbon material would open up a chance to investigate an expansive composition matrix for potential improvements of the cell performance. In addition, for potential commercialization, processes that are clean and high-throughput are desired. Laser pyrolysis of hydrocarbons has been established as a widely adopted gas phase production of carbon nanoparticles. In particular, multilayered particles with concentric graphitic shells, commonly called carbon nano-onions, are of interest as the size, shape and the number of graphitic shells are easily tuned by adjusting the experimental parameters. In this work, we present a CO2 laser induced pyrolysis of gaseous hydrocarbons (such as acetylene and ethylene) that generates various types of carbon nanoparticles, and demonstrate that these carbon nano-onions have superior durability and electrical conductivity to commonly used commercial carbon materials such as Vulcan XC-72. Platinum-decorated carbon nano-onions have been used to fabricate PEMFCs and they are shown to have comparable performance to conventional cells, and the accelerated stress test reveals that the durability of the cells have improved.