Size Of Carbon Nanoparticles Research Articles

Reuse of Lignin to Synthesize High Surface Area Carbon Nanoparticles for Supercapacitors Using a Continuous and Single-Step Aerosol Method.

There is a growing demand for the synthesis of high surface area carbons, also known as carbon nanoparticles (CNPs). Existing synthesis methods for high surface area carbons have limited environmental benignity and economic viability due to the requirement of multistep and batch processes and harsh activating and/or templating chemicals. Herein, we demonstrate the synthesis of high surface area CNPs from lignin, a waste byproduct, through a single-step, continuous gas phase aerosol technique without the use of activating or templating chemicals. This continuous approach requires significantly less time for synthesis: on the order of seconds in comparison to hours for conventional methods. Properties of carbon materials synthesized from lignin are controlled by temperature and residence time, and the role of these parameters inside the aerosol reactor on carbon nanoparticle size, morphology, molecular structure, and surface area is systematically investigated. Furthermore, the as-obtained carbon nanoparticles are tested for specific capacitance, and the best-performing material (surface area 925 m2/g) exhibited a specific capacitance of 247 F/g at 0.5 A/g with excellent capacity retainment of over 98% after 10,000 cycles. This is a clear demonstration of their superior performance compared with supercapacitors synthesized earlier from lignin. Overall, the simple (single-step, continuous, and rapid) operation and the avoidance of the use of activating/templating chemicals make the aerosol technique a promising candidate for the scalable and sustainable synthesis of CNPs from lignin.

Facile Synthesis of Catalyst Free Carbon Nanoparticles From the Soot of Natural Oils

The growth of carbon nanostructures from vegetable oils using a modified conventional approach is a simple and environmentally friendly technology with controllable features. The goal of this study is to develop a simple and environmentally friendly process for making carbon nanoparticles using commercially available, low-cost vegetable oils. The technique involves the controlled burning of “Mustard”, “Olive”, and “Linseed” oils using the traditional clay lamps and collecting the carbon soot on a ceramic plate. The prepared carbon nanoparticles were purified through sonication and subjected to characterization using powder X-ray diffraction, SEM, Fourier transformed infrared, Thermogravimetric and differential scanning calorimetric analyses. The average particle size of carbon nanoparticles as investigated by powder X-Ray Diffraction analyses was found to be 18, 24, and 57 nm for mustard, olive and linseed oils respectively. SEM analyses revealed the surface morphology of these carbon nanostructures as spherical particles. Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) providing knowledge about the thermal stability of these carbon nanoparticles. The synthesized carbon nanoparticles were screened for antibacterial activities against different species (e.g., Pseudomonas aeruginosa, Streptococcus haemolyticus, Proteus refrigere and Staphylococcus aureus) and fruitful results have been obtained.

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.

Superhydrophobicity of hierarchical nanostructure of candle soot films

Candle soot containing carbon nanoparticles can form hierarchical structure films. We prepared soot films by using glass slides blocking candle flame in the middle of the flame. The hierarchical nanostructures of the carbon nanoparticles films were confirmed by scanning electron microscopy and transmission electron microscopy. Carbon nanoparticle size was 49.2 ± 9.0 nm from SEM, which agrees to 37.9 ± 8.5 nm from TEM. The contact angles of water droplets on these films are more than 150°, indicating superhydrophobic surface. Decrease contact angles of water droplets were observed with an increase deposition time. The decrease of contact angle was saturated at about 150° when the deposition time reaches 180 s. Cassie-Baxter state was attributed to describe superhydrophobicity of carbon nanoparticles films because the hierarchical nanostructures of the surface provide a large fraction of hollows on the surface. We proposed that the contact angle dependence on deposition time was governed by the increase of the distance between nanopillars in carbon nanoparticles films.

Synthesis of Large Pore Carbon Nanoparticles for Removal of Malachite Green

In this work, we have synthesized high surface area and large pore volume carbon nanoparticles (CNP) by a simple and easy sol-gel approach. The sol was prepared by mixing Pluronic F127 and phloroglucinol-terephthalaldehyde in acidic ethanol solution and the gel was formed after the vacuum removal of ethanol. In the sol-gel process, hydrophobic segments of Pluronic F127 forms enhanced hydrogen bonding with trihydroxyl groups of phloroglucinol. A polymeric network of carbon precursor was also prepared by making the interconnectivity between four phloroglucinol and one terephthalaldehyde molecules. After thermal polymerization and carbonization of the gel, the CNP had a very high surface area (1441 m² g⁻¹) and large pore volume (1.7 cm³ g⁻¹) with narrow micropore (1.0 nm) and mesopore (2.3 nm) diameters. The mesopore was developed due to the enhanced hydrogen bonding between Pluronic F127 and phloroglucinol, while the micropores were generated due to hydrocarbon polymeric network of phloroglucinol-terephthalaldehyde. The CNP had a size about ca. 20 nm. The CNP were applied for the removal of the highly hazardous water pollutant malachite green (MG) and achieved a very high adsorption capacity (1892 mg g⁻¹). The commercials powder activated carbon (PAC) was also applied for the removal of MG and achieved an adsorption capacity of PAC was 1390 mg g⁻¹. It believes that shape and size of CNP and PAC played an important role in the adsorptive removal of MG.

A Study on Fabrication, Dispersion and Surface Coating of Nanocarbon for MgO-C Refractories

Spherical carbon nanoparticles were synthesized by sol-gel polymerization of resorcinol and formaldehyde in the presence of CTAB(cetyltrimethyl ammonium bromide) and subsequent carbonization at 900 in N2 atmosphere. It is found that the amount of CTAB, water and catalyst showed a significant impact on the morphology and size of carbon nanoparticles. The magnesia-carbon (MgO-C) bricks containing 1~4 wt% nanocarbon were prepared by adding various types of carbon black (CB), multi walled carbon nanotubes (CNT) and synthesized nanocarbon. The mechanical properties, oxidation resistance and corrosion resistance of the MgO-C brick in which the nanocarbon is added was investigated. The MgO-C refractories were characterized by Field Emission Scanning Electron Microscope (FE-SEM, MIRA II LMH), Cold Crush Strength (CCS).

Synthesis of Spherical Carbon Nanoparticles and their EDLC Properties

Spherical carbon nanoparticles were synthesized by sol-gel polymerization of resorcinol and formaldehyde in the presence of CTAB(cetyltrimethylammonium bromide) and subsequent carbonization at 900°C. It is found that the amount of CTAB, water and catalyst showed a significant impact on the morphology and size of carbon nanoparticles. According to the BET surface area and capacitance, the nanoparticles were divided into two groups. The carbon nanoparticles with surface area of 725-758 m2/g showed capacitance between 120-140 F/g, while those with surface area of 596-649 m2/g showed capacitance only 60-80 F/g. Difference in the pore size of 1.5 nm to 3.0 nm probably contributed to the difference of capacitance.

Effect of active impurities on the condensation of nanoparticles from supersaturated carbon vapor in the combined laser photolysis of C3O2 and H2S

The effect of active H2S, HS·, and atomic hydrogen impurities on the condensation of highly supersaturated carbon vapor obtained in the combined laser photolysis of a mixture of C3O2 and H2S diluted with argon was studied. The concentrations of carbon vapor, HS·, and atomic hydrogen obtained in the laser photolysis of the mixture were determined using the absorption cross sections of C3O2 and H2S molecules measured in this work and the measured amount of absorbed laser radiation. The time profiles of the sizes of growing nanoparticles synthesized in C3O2 + Ar and C3O2 + H2S + Ar mixtures were measured using the laser-induced incandescence (LII) method. An improved LII model was developed, which simultaneously took into account the heating and cooling of nanoparticles and the temperature dependence of the thermophysical properties of nanoparticles, as well as the cooling of nanoparticles by evaporation and thermal emission. The size distributions of carbon nanoparticles formed in the presence and absence of active impurities were determined with the use of a transmission electron microscope. The final average size of carbon nanoparticles was found to decrease from 12 to 9 nm upon the addition of H2S to the system, whereas the rate of nanoparticle growth decreased by a factor of 3, and the properties of nanoparticles changed. In particular, the translational energy accommodation coefficient for Ar molecules at the surface of carbon nanoparticles was found to decrease from 0.44 to 0.30. A comparison of the calculated total carbon balance at the early stage of nanoparticle formation with experimental data demonstrated that the reaction C + H2S → HCS· + H, which removes a portion of carbon vapor from the condensation process, has a determining effect on the carbon balance in the system. It was found that HS· and atomic hydrogen affect the carbon balance in the system only slightly. Thus, the experimentally observed decrease in the rate of nanoparticle growth and in the sizes of nanoparticles can be explained by a decrease in the concentration of free carbon upon the addition of H2S molecules to the system.

Fabrication and nano-structure control of carbon aerogels via a microemulsion-templated sol–gel polymerization method

Carbon aerogels were successfully fabricated by a microemulsion-templated sol–gel polymerization method. When a suitable molar ratio of surfactant to resorcinol (S/R) and an appropriate resorcinol–formaldehyde concentration were selected, the organic gels thus obtained could be dried with little shrinkage by heating at ambient pressure. The size of carbon nano-particles and the pore size of carbon aerogels thus produced decrease with an increase of S/R. The highest specific surface area and specific mesopore volume of the carbon aerogels prepared by our method were 620 m 2 g −1 and 1.14 cm 3/g, respectively.