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The electrospinning technique was used to prepare nanofibers samples consisting of three groups, each group has a different polystyrene concentration (12, 14, 16 wt.%). Multiwalled carbon nanotubes were added to each group with four ratios to yield four samples comprising (polystyrene/MWCNT) constituents. The UV-Visible test was carried out to know how uniformly nanofibers and Mutli-walled carbon nanotubes were distributed in the polymeric nanofibers and their effect on the final nanofiber's properties through the absorption peaks. The morphological test used "Field Emission Scanning Electron Microscope". The results showed that; MWCNTS has a dominant effect on prepared nanofibers in the (12 wt.% Polystyrene) group, and both (PS, MWCNT) have a shared effect, highest steady absorption curves, and uniformly scattered radiation at (14 wt.% PS) group, and random results at (16 wt.% PS) group. From FESEM results we notice that increasing polymer concentration causes an increase in the nanofiber's diameter and beads formation chance increases at (12,16 wt.% PS) groups. In the group of (14 wt.% Polystyrene), it produces nanofibers with free beads and uniform distribution, the addition of MWCNT lowers the diameter of nanofibers much more and enhances the orientation, and improves their UV absorption, strength, and mechanical properties. [ABSTRACT FROM AUTHOR]

Polymeric nanocomposites of polystyrene nanofibers and multiwall carbon nanotubes and natural pigment were synthesized using electrospinning technique the polystyrene concentration was 12 wt.% and multiwall carbon nanotube was added by (0, 100, 140, 200 ppm), and natural pigment added by two drops (0.063 g) to the prepared solutions and many tests were carried out to the prepared solutions and the final samples. The solution tests included viscosity test by using cone-plate viscometer and surface tension test using du-nouy ring method. The nano textiles tests included the Fourier transform infrared spectroscope (FTIR) test, Field emission scanning electron microscopy (FESEM) test, contact angle test, and ultraviolet test to extract the energy bandgap using (tauc plot) method. The tests results showed that the viscosity increased by increasing the multiwall carbon nanotube and natural pigment and surface tension slightly increased at a high ratio of 200 ppm of multiwall carbon nanotube and natural pigment and physical type of reaction between the components were confirmed through FTIR, and the addition of multiwall carbon nanotube and natural pigment makes the fibers smoother and fewer beads formation and increase the multiwall carbon nanotube addition made the samples more hydrophobic and the charts of tauc plot show that increasing the MWCNT with natural pigment addition will increase the electrical sensitivity of the prepared samples in which the energy band gap dropped from 1.18 ev to 0.2 ev for the sample of Polystyrene/200 ppm MWCNT/natural pigment this is regarded as an indication of using it as a typical electrical sensor. [ABSTRACT FROM AUTHOR]

In this study, conductive and transparent polycaprolactone (PCL)/carbon black (CB) nanofibers are produced by electrospinning. In order to investigate the effect of solvent system on the optoelectrical properties of PCL/CB nanofibers, the fibers are produced from two different solvent systems; namely, chloroform (CHL) and dimetyl formamid (DMF). For optoelectrical characterization, nanofibers are produced with different deposition times in the range of 1–10 minutes. Surface, optical, electrical and optoelectrical properties of the PCL/CB nanofibers are evaluated. Nanofibers produced from CHL solvent system results in non-uniform nanofibers with higher diameters. They also give a larger diameter distribution. On the other hand, nanofibers with uniform and smaller diameters are obtained from DMF system. UV-spectrophotometer analysis show that nanofiber mats produced from both solvent systems have similar optical transparencies. Lower sheet resistance values are obtained with the nanofiber mats produced from DMF system according to electrical characterizations. Higher Figure of Merit values are calculated for the nanofiber mats produced in DMF solvent system. Considering all the results, it can be concluded that PCL/CB nanofibers produced from DMF solvent system are better candidates compared to the nanofibers produced from CHL solvent system for optoelectrical applications. [ABSTRACT FROM AUTHOR]

Aiming to solve/respond the mist of the carbon-networking crisis by the present and foreseen global turbulences, either of economic, bionic, or ecologic nature, one may advance the next level approach to the cluster-to-metacluster of nano-technology mutagenesis: astralisation. Viewed as the new symmetrical/asymmetrical based openness, it surpasses the global limits of networking "contagion" by extending its boundaries in space, time and energy; actually, it extensively uses the quantum present and yet-to-come carbon-nanoscience, technology and challenges in order to design the information and substance synthesis at the distance as transmitted in nano-instances by activating specific potential of matter (industrial) and know-how (organizational): wave-functions and ordering degree combined in what it can be called as the strategic quantum management; it essentially describes how the activation of a nano-potential of a waving-system propagates(processes) and transform (taking-observable-form)through quantum-pairing of metaclusters –into the clusters (fullerenic packing), meta-clusters (via graphenic type of packing, Stone-Wales rotations included), and astralons (analogs of everted nanotubes' packing, e.g., Klein-Bottle); first strategic projection and patterning is also given in terms of a proposed chart of astralisation criteria and of associated composite index as applied on identified 8-folded ways of glocal (global-local) nano-ecolo-management. [ABSTRACT FROM AUTHOR]

In this work, data of Rodriguez-Baker et al. and some others were analyzed and interpreted in relation to the long-term, i.e., about 25 years, problem of "super" storage (intercalation) of "reversible" (at 300 K) hydrogen (∼38 ± 10 wt.%, i.e., the atomic ratio (H/C) ≈ 7 ± 3)), along with "irreversible" hydrogen (∼11 ± 3 wt.% ((H/C) ≈ 1.5 ± 0.4)) into graphite nanofibers (GNFs). For a more in-depth study of the a problem, an effective methodology of processing and analyzing the thermal desorption spectra of hydrogen and the related thermogravimetric data was modified and used. It was shown that the above noted extraordinary data on the "super" storage of hydrogen in GNFs are neither an error nor a hoax, as most researchers believed. The necessary conditions were determined to reproduce this extraordinary data. It has also been shown that the Rodriguez-Baker team can reproduce "normal," i.e., typical results obtained by other researchers on hydrogen storage in GNFs. [ABSTRACT FROM AUTHOR]

The paper presents the results of experimental studies in the scope of formation of bulky aluminum based composite materials (CM) with carbon nanofibers (CNF), including the research methods of hot extrusion and rolling. Extrusion manufacture of bulky composite materials contributes to obtain billets with a minimum compression degree (λ = 1.5). To reduce shear deformations and formation of pores in extruded billet, the extrusion process modes were selected experimentally. In the course of further rolling operation, mechanical properties increase twice and inhomogeneity is compensated after significant compression of the extrusion billets, and the shear deformations are reduced in full volume of the material. Bulky materials gain high hardness, wear resistance and strength. The economically alloyed composite material has feasible prospects to be applicable in lightweight structures for aviation and automobile industries. [ABSTRACT FROM AUTHOR]

We report the synthesis of a novel type of carbon-based nanostructure, which is composed of a string of carbon nanopearl chains (CNPCs) with a connection structure of carbon nanofibers using a chemical vapor deposition method. Regularly spaced, nanometer-sized balls of graphitic carbon are found on the amorphous nanofibers. The nanopearls have nanometer-sized spheres, bodies in diameter varying from tens of nanometers to hundreds of nanometers, with solid interiors. The chain connections have a length ranging from several nanometers up to micrometers between two nanopearls. The nanopearls connect each other by the nanofibers, thus forming a chain. The CNPCs have potential for use as reinforcing matrix to produce strong and tough carbon-based nanocomposites. [ABSTRACT FROM AUTHOR]

Nitrogen doped graphene quantum dots (N-GQDs) have attracted much attention because of their superior electronic and optical properties. The preparation of N-GQDs can be usually performed via a top-down method using vairous nanocarbon as raw materials. However, most carbon materials are powder, which increases the difficulty of separating quantum dots from the reaction solution. Herein, we verified a feasibility of N-GQDs preparation with a bulk carbon film composed of N-doped carbon nanofibers as raw mateial via an acid vapor cutting approach (only 1 ml nitric acid was used in the method). The synthesis method effectively voids a tedious separation process. And the as-prepared N-GQDs exhibit good dispersion, high photostability and blue-green fluorescence. Subsequently, fluorescence experiments confirmed the fluorescence of N-GQDs was quenched selectively by Fe3+ via the unique coordination interaction between them and recovered with the addition of AA. Based on the quenching (off) and recovering (on) processes, fluorescent sensor for Fe3+ and OFF-ON fluorescent sensor for AA were fabricated, showing good selectivity and wide linear range. Finally, the constructed sensors were successfully applied for Fe3+ and AA detection in real samples such as tap water and human urine. [ABSTRACT FROM AUTHOR]

The SiO2/WO3/NiWO4 composites modified carbon nanofibers (SiWNi-CNFs) were prepared by a facile electrospinning method with following carbonization process under nitrogen atmosphere. The as-obtained SiWNi-CNFs were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray photoelectron spectra (XPS), X-ray powder diffraction (XRD), FT-IR spectroscopy and Raman spectroscopy. As revealed by the electrochemical measurement, the SiWNi-CNFs prepared with SiW12/NiAc2 molar ratio of 1:1 presented best hydrogen evolution activity with a small Tafel slope (48 mV dec−1) among all the as-prepared samples. Notably, the as-prepared catalysts exhibit a small onset potential (0.29 V vs. reversible hydrogen electrode), high current density and excellent stability. The experimental results pointed that the SiWNi-CNFs processes more efficient hydrogen evolution properties than that other contrast samples. This is due to the SiO2/WO3/NiWO4 composite modified on the surface of carbon nanofibers can generate numerous active sites from the synergistic effect of each component. At the same time, the intimate combination of ternary oxide and carbon nanofibers can accelerate the electron transfer, enhance the stability and hinder the aggregation of active components during the carbonization. Moreover, the net-like structure stacked by carbon nanofibers should render the exposure of active sites and facilitate the mass transport for the HER process. [ABSTRACT FROM AUTHOR]

Construction of transition metal oxides-based carbonaceous nanostructures has been regarded as one of the most effective strategies to prepare the electrodes for high-performance supercapacitors. In this work, NiCo2O4 embedded carbon nanofibers (NiCo2O4-CNFs) are synthesized by the combination of one-step electrospinning and following thermal treatment. The obtained NiCo2O4-CNFs are evaluated as electrodes for supercapacitors. The testing results indicate that the NiCo2O4-CNFs present high specific capacitance of 836 F g−1 (vs. 38.02 F g−1 for carbon nanofibers (CNFs)) at 5 A g−1, and outstanding cycling ability with 80.9% retention after 2000 cycle times. Such excellent performances benefit from the integration of electric double layer capacitors and pseudocapacitors. This kind of NiCo2O4-embedded carbon nanofibers can serve as a promising candidate for electrode materials for supercapacitors. [ABSTRACT FROM AUTHOR]

This work shows, for the first time, that the multi-walled carbon nanotubes (MWCNTs) exhibit the catalytic activity in the ethylene hydrogenation. MWCNTs with the average diameter of 35 nm were prepared by CVD from ethylene as a carbon source at 700 °C. TEM, SEM, and XRD indicate that MWCNTs are characterized by a sufficiently high defectiveness. FTIR highlights that the catalytic process occurs in the presence of the hydroxyl and carbonyl surface groups. We demonstrate the high catalytic stability of MWCNTs at temperatures up to 400 °C. [ABSTRACT FROM AUTHOR]

Carbon nano-onions with hollow/shell structures were directly synthesized by a combustion synthesis process, using poly (tetrafluoroethylene) powders and ferrous chloride as raw materials. The growth of an intermediate FeF2core template which is a dynamic-controlled process is demonstrated to be the key factor to prepare hollow carbon nano-onions. Raman spectroscopy revealed that the as-synthesized product was mainly composed of amorphous carbon. Such unique process suggests a new method for controlling the growth of an intermediate core to prepare different hollow carbon nanostructures. [ABSTRACT FROM PUBLISHER]

Electrospun polyacrylonitrile (PAN) nanofibers were pre-oxidized under 1, 2, and 3 wt% of KMnO4aqueous solutions. Scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction and Raman spectroscopy were used to study the effect of KMnO4concentration on the structures and properties of PAN-based heat stabilized and carbonized electrospun nanofiber mats. In FT-IR spectra of the preoxidized samples a new peak at 2340 cm−1designated to MnO4–C=N conjugation was revealed. Chemical modification by KMnO4was used to decrease the average diameter, increase the Bragg spacing, and decrease the preferred orientation and the crystal size. According to the Raman spectra, the bandwidths of the G mode became wider in the cases of preoxidized samples, while the G mode intensities belonging to the crystalline regions were decreased. According to the TGA studies, the weight losses in the preoxidized samples were severe due to the permanganate attack. [ABSTRACT FROM PUBLISHER]

The first derivatives of diterbium fullerenes were successfully synthesized through the photochemical reaction of a large carbon cage-based diterbium fullerene Tb2C90with 2-admantane-2,3-[3H]-diazirine. A monoadduct isomer, Tb2C90Ad (Ad = admantylidene), was isolated by multi-stage high-performance liquid chromatography with toluene as eluent. The formation of a series of derivatives of diterbium fullerenes as well as the success in the isolation of Tb2C90Ad was confirmed by high-performance liquid chromatography and matrix-assisted laser adsorption/ionization time-of-flight mass analyses. Vis-NIR absorption showed that the electronic property of Tb2C90was largely pertained in the derivative, although a slight red-shift was observed for Tb2C90Ad. Cyclic voltammetric determination indicated that the redox potential of Tb2C90Ad was shifted cathodically in comparison with pristine Tb2C90owing to the electron transfer from Ad to carbon cage. [ABSTRACT FROM PUBLISHER]

Electrospun carbon nanofibers (ECNFs) have many qualities that make them attractive for applications in various fields of technology. For many applications, it is necessary to modify the surface of CNFs by chemical functionalization. Here, a systematic functionalization of polyacrylonitrile (PAN)-based ECNFs by oxidation in concentrated nitric acid was examined. The effects of oxidation on the microstructural, electrical, and mechanical characteristics have been studied. The Fourier transform infrared spectroscopy results revealed the time-dependent functionalization of ECNFs. However, according to the scanning electron microscopy, there was no considerable change in the surface morphology of CNFs due to functionalization. The microstructures as well as electrical and mechanical properties were severely dependent on oxidation duration according to X-ray diffraction and Raman spectroscopies as well as conductivity and mechanical strength measurements, respectively. Increase in oxidation duration led to more structural disorders and noticeable decrease in electrical conductivity and mechanical strength. [ABSTRACT FROM AUTHOR]

The main objective of this work was to evaluate nanocomposites formed by TiO2-CNT (carbon nanotube) and TiO2-C (resorcinol/formaldehyde) via a sonocatalytic process. The synthesis of composites was performed by the sol-gel method using titanium isopropoxide (Ti(OPr)4-TTIP), acetic acid and ethylene glycol as dispersing medium. Ultrasound was used as the irradiation source and methylene blue was chosen as a model substance. In addition, the adsorption capacity was studied in an attempt to achieve greater ratio degradation/adsorption. The methylene blue concentration after adsorption and sonocatalysis was investigated by UV–vis spectroscopy. It was found that adsorption was an important factor to achieve high degradation capacity. However, the sonocatalytic activity decreased when adsorption was too intense. [ABSTRACT FROM PUBLISHER]

In this work, three different methods of preparation of polyacrylonitrille (PAN) with carbon black (CB) solutions further used in electrospinning for producing conductive fiber mats are discussed. CB is used as conductive filler. Content of CB in polymer matrix is varied, CB/PAN = 1/2, 1/1, and 3/2. The solution properties and obtained fiber morphology are analyzed. The effect of preparation on fiber morphology and conductivity is analyzed, as well as the effect of sonication on solution properties, morphology, and conductivity of PAN+CB samples. [ABSTRACT FROM PUBLISHER]

Carbon naonfibers (CNFs) were heat-treated in a spark plasma sintering (SPS) system with vacuum condition at 1500°C with various uniaxial pressures. The microstructural evolutions of CNFs under both high temperature and additional pressure were investigated by scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. It is proposed that the high temperature is contributing to the formation of high ordered and large crystalline graphitic layers, while applied pressure is in favor of cutting down the CNFs to shorter ones and coalescing them to form micro-sized graphitic sheets. Our results propose that the SPS is an efficient route to explore the materials’ structural conversions at high pressure and high temperature. [ABSTRACT FROM AUTHOR]

Solubility of acid functionalized carbon nanofibers is found to be greatly dependent on a degree of functionalization and pH value of solution. The solubility is close to zero at pH < 1, sharply increases at pH > 1.0–1.5 and slowly declines with further growth of pH value up to 12. Addition of zirconium salts to the solution notably changed the behavior of CNFs; in a pH window between 1.5 and 3.5 the solution contains zirconium and CNFs in a large concentration. [ABSTRACT FROM AUTHOR]