Carbonaceous Nanotubes Research Articles

Synthesis of Nitrogen-Doped Carbonaceous Nanotubes Array via a Annealing Process and its use for Electrocatalytic Oxygen Reduction Reaction

Synthesis of Nitrogen-Doped Carbonaceous Nanotubes Array via a Annealing Process and its use for Electrocatalytic Oxygen Reduction Reaction

CNT-Ni-Pd Nanocomposite Films for Optical Gas Sensor

Abstract We present the optical properties of the nanocomposite nickel - carbonaceous (Ni-C) and carbon nanotubes, palladium-fullerene (CNT- Ni-Pd) films obtained by various methods. The initial film was prepared by physical vapor deposition (PVD) method using two separated sources: fullerene C60 (as carbon source) and nickel acetate (as metal source). Next, the initial film was modified by chemical vapor deposition (CVD) using xylene at temperature ∼ 650 °C, as a result carbon nanotubes containing inside Ni grains were synthesized. Then, on the carbon nanotubes, palladium-fullerene films were deposited using PVD process, these samples were named by us as (CNT- Ni-Pd) films. All (Ni-C) films and (CNT-Ni-Pd) films were studied by SEM. These nanostructures were analyzed by optical method using measuring the variation of the absorbance of different gases (H2, CO, NO2).

Characterization of Chiral Carbonaceous Nanotubes Prepared from Four Coiled Tubular 4,4′-biphenylene-silica Nanoribbons

Characterization of Chiral Carbonaceous Nanotubes Prepared from Four Coiled Tubular 4,4′-biphenylene-silica Nanoribbons

Characterization of Chiral Carbonaceous Nanotubes Prepared from Four Coiled Tubular 4,4′-biphenylene-silica Nanoribbons

Four dipeptides derived from phenylalanine were synthesized, which can self-assemble into twisted nanoribbon in deionized water. The handedness of the organic self-assemblies was controlled by the chirality of the phenylalanine at the terminals. Coiled 4,4'-biphenylene bridged polybissilsesquioxane tubular nanoribbons were prepared using the organic self-assemblies as the templates. The circular dichroism spectra indicated that the biphenylene rings preferred to twist in one-handedness within the walls of the samples. After carbonization and removal of silica, single-handed coiled carbonaceous tubular nanoribbons were obtained. The Raman spectra indicated that the carbon was amorphous. The diffuse reflectance circular dichroism spectra indicated the tubular carbonaceous nanoribbons exhibited optical activity.

N- and O-doped carbonaceous nanotubes from polypyrrole for potential application in high-performance capacitance

By the reactive self-degraded template-directed synthesis and further carbonization, N- and O-doped carbonaceous nanotubes from conducting polymer (polypyrrole) precursor have been prepared. After being chemically activated by KOH, specially, with the weight ratio of KOH to polypyrrole nanotubes of 2 and 4, two samples of activated carbonaceous polypyrrole nanotubes (ACPN-2 and ACPN-4) with an uncapped morphology were obtained. The ACPN-4 possesses high heteroatom content (14.85%) and specific surface area (1226 m2 g−1), and exhibits a reversible capacitance of 470 F g−1 at the current density of 0.2 A g−1, and 280 F g−1 even at a higher current density of 10 A g−1. Moreover, these nanotubular structured materials have also shown excellent cycling performance with no capacitance loss over 10,000 cycles. Furthermore, these carbonaceous nanotubes achieved a high CO2 adsorption uptake of 3.9 mmol g−1 at 273 K and 2.5 mmol g−1 at 298 K.

Preparation of Single‐Handed Helical Carbon/Silica and Carbonaceous Nanotubes by Using 4,4′‐Biphenylene‐Bridged Polybissilsesquioxane

Single-handed, helical, 4,4'-biphenylene-bridged polybissilsesquioxane nanotubes were prepared by using the self-assemblies of a pair of chiral low-molecular-weight gelators as templates. Single-handed, helical, carbon/silica nanotubes were obtained after carbonization of the self-assemblies, and single-handed helical carbonaceous nanotubes were then obtained by removal of silica with aqueous HF. Samples were characterized by using field-emission SEM, TEM, X-ray diffraction, thermogravimetric analysis, Raman spectroscopy, and circular dichroism. The polysilsesquioxane and carbonaceous structures exhibited optical activity. The walls of the carbon/silica and carbonaceous nanotubes were predominantly amorphous carbon. The surface area of the left-handed, helical, carbonaceous nanotubes was 1439 m(2) g(-1), and such materials have potential applications as catalyst supports, chirality sensors, supercapacitor electrodes, and adsorbents.

Synthesis of Enantiopure Carbonaceous Nanotubes with Optical Activity

In one step, self-assembled helical polypyrrole nanotubes were carbonized to enantiopure chiral carbonaceous nanotubes with a partially graphitized nanostructure (see picture). The ordered helical arrangement of the carbon nanostructure resulted in enantiomeric materials with distinct optical activity. Moreover, their unique structure endowed them with high reversible storage capacity of lithium ions.

Synthesis of Enantiopure Carbonaceous Nanotubes with Optical Activity

In einem Schritt wurden selbstorganisierte helicale Polypyrrol-Nanoröhren zu enantiomerenreinen chiralen kohlenstoffhaltigen Nanoröhren mit teilweise graphitisierter Nanostruktur (siehe Bild) karbonisiert. Die geordnete helicale Anordnung der Kohlenstoff-Nanostrukturen ergab enantiomerenreine Materialien mit eindeutiger optischer Aktivität. Darüber hinaus verleiht ihnen ihre einzigartige Struktur eine hohe reversible Speicherkapazität für Lithiumionen.

High viscosity polyethylene-based electroconductive nanocomposites: carbon nanotubes versus carbon nanofibres

In this study, two types of carbonaceous nanoparticles, i.e., carbon nanotubes (CNT) and carbon nanofibers (CNF) were compared with respect to their ability for endowing electroconductive properties to a high viscosity high density polyethylene (HDPE) by melt blending. Only CNT were found to be efficient to reach electrical percolation in high density polyethylene (HDPE) system at small amount of nanoparticles (between 2 and 5 wt%). Despite different treatments performed onto CNF either to remove surface impurities or to tune their interaction with the polyolefinic matrix by adding a modifying agent compatible with HDPE, it was not possible to obtain conductive composites even in the presence of a high amount of CNF, i.e., 10 wt%. Such a behavior resulted from the intensive aggregation of the CNF that proved to be highly difficult to individualize upon dispersion within high viscosity HDPE.

Carbon/metal nanotubes with tailored order and configuration by direct carbonization of inverse block copolymer micelles inside nanoporous alumina

Carbonaceous nanotubes decorated with metal nanoparticles were obtained by heating inverse block copolymer micelles loaded with metal precursors inside nanoporous alumina. Simple changes in the applied temperature profile allowed tailoring of the wall morphology of the nanotubes and the spatial arrangement of the metal nanoparticles.

Synthesis and chemical etching of Te/C nanocables

In this paper, Te/C nanocables were fabricated by a hydrothermal method in the presence of cetyltrimethylammonium bromide (CTAB). The products were characterized in detail by multiform techniques: transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray analysis and Fourier transform infrared (FTIR) spectroscopy. The results showed that the products were nanocables with lengths of several microns, core about 20 nm in diameter, and a surrounding sheath of about 60–80 nm in thickness. Te/C nanocables were tailored freely by chemical etching. Carbonaceous nanotubes and Te/C nanocables with fragmentary Te core were obtained by adjusting time of chemical etching.

Characterisation of Ni-C films obtained in PVD/CVD process

Abstract The work presents the results of the scanning electron microscopy (SEM) and Raman spectrometry studies of carbonaceous nanostructures containing nickel nanocrystallites. The films were obtained using a two-step method. In the first phase the Physical Vapour Deposition (PVD) method was applied, whereas in the second Chemical Vapour Deposition (CVD) method was used. The paper presents results for samples with various Ni content obtained with different parameters of the two-phase technological process. The research confirms that the thin films obtained by PVD method contain Ni nanocrystallites distributed in a carbonaceous matrix. The matrix is composed of various carbon allotropes (amorphous carbon, graphite, fullerene). The thin films made by CVD method make a matrix when multiwalled, carbonaceous nanotubes are obtained. Depending on the technological process parameters of each phase, we obtain multiwall nanotubes with a various degree of defects.

Temperature effect of electrorheological fluids based on polyaniline derived carbonaceousnanotubes

Nitrogen-enriched carbonaceous nanotubes (N-CTs) were prepared by the carbonization ofpolyaniline (PANI) nanotubes in vacuum and were demonstrated to possess goodelectrorheological (ER) performance. In this paper, the temperature dependence of the ERproperties of the suspension composed of N-CTs in silicone oil was systematicallyinvestigated by steady shear viscosity and dynamic viscoelastic measurements. Theseshowed that under electric fields the N-CT suspension showed good temperature stabilityof its ER properties though its zero-field viscosity decreased with elevated temperatures.Meanwhile, the flow curve of shear stress versus shear rate also maintained a stable leveland the critical shear rate shifted towards high values as the operating temperatureincreased. The dynamic viscoelastic measurement showed that the storage modulus slightlyincreased with increasing operating temperature, also confirming the good temperaturestability of the ER properties of the N-CT suspension. The dielectric spectra of the N-CTsuspension and the dielectric parameters calculated by the Cole–Cole equation couldexplain the temperature dependence of the ER properties of the N-CT suspension.

Dissolution of poly(vinyl alcohol)-modified carbon nanotubes in a buffer solution

Multiwalled carbon nanotubes (MWCNTs) were modified with a watersoluble poly(vinyl alcohol) (PVA) polymer (MWCNTsPVA). The dissolution of the MWCNTsPVA in TrisHCl buffer solution was carried out in a shaking water bath by a soaking method. The microstructural changes of the MWCNTsPVA during soaking was investigated using Fourier transforminfrared spectroscopy, differential scanning calorimetry, transmission electron microscopy, and Xray diffraction. It is found that part of the MWCNTsPVA was dissociated into amorphous carbonaceous debris, but most of tubular structures were retained after 21d of soaking. The dissolution process revealed that the C—C bonds of the MWCNTsPVA were brokendown with the generation of carbonaceous debris and residual carbon nanotube la￣yers, and the latter can be further dissociated into amorphous carbonaceous debris. A possible dissolution mechanism of the MWCNTsPVA in the buffer solution was proposed and discussed. The surface modified MWCNTs have many defects and open C—C bonds on the surfaces of the CNTs. The dissolution of the PVA in the buffer solution leads to a release of carbon atoms on the outer surface of the MWCNTs. It results in a further rupture of the C—C bonds and destroys the tubular structure .

Fabrication and Chemical Etching of Ag/C Nanocables

In this paper, Ag/C nanocables were synthesized via a one-step simple hydrothermal route by using glucose as reducing agent and carbon source, AgNO3 as silver source. The products are characterized in detail by multiform techniques: X-ray diffraction, energy-dispersive X-ray analysis, scanning electron microscopy, transmission electron microscopy. The results show that the obtained products are coaxial nanocables with lengths of several micrometers, about 200-500 nm in diameter, and a surrounding sheath about 80-100 nm in thickness. Different products including carbonaceous nanotubes and nanocables with fragmentary Ag core were obtained by adjusting time of chemical etching.

Dissolution of poly(vinyl alcohol)-modified carbon nanotubes in a buffer solution

Multiwalled carbon nanotubes (MWCNTs) were modified with a water-soluble poly(vinyl alcohol) (PVA) polymer (MWCNTs-PVA). The dissolution of the MWCNTs-PVA in Tris-HCl buffer solution was carried out in a shaking water bath by a soaking method. The microstructural changes of the MWCNTs-PVA during soaking was investigated using Fourier transform-infrared spectroscopy, differential scanning calorimetry, transmission electron microscopy, and X-ray diffraction. It is found that part of the MWCNTs-PVA was dissociated into amorphous carbonaceous debris, but most of tubular structures were retained after 21 days of soaking. The dissolution process revealed that the C-C bonds of the MWCNTs-PVA were broken-down with the generation of carbonaceous debris and residual carbon nanotube layers, and the latter can be further dissociated into amorphous carbonaceous debris. A possible dissolution mechanism of the MWCNTs-PVA in the buffer solution was proposed and discussed. The surface modified MWCNTs have many defects and open C-C bonds on the surfaces of the CNTs. The dissolution of the PVA in the buffer solution leads to a release of carbon atoms on the outer surface of the MWCNTs. It results in a further rupture of the C-C bonds and destroys the tubular structure .

Conductivity and polarization of carbonaceous nanotubes derived from polyaniline nanotubes and their electrorheology when dispersed in silicone oil

Nitrogen-enriched carbonaceous nanotubes (N-CTs) were prepared by the heat treatment of conducting polyaniline (PANI) nanotubes and then were used as new carbonaceous electrorheological (ER) fluids. Characterization showed that the nanotubular morphology of the original PANI was preserved after heat treatment, whereas the chemical structure and conductivity were changed significantly depending on the heat treatment temperatures. Under electric fields, the rheological properties of the N-CT suspensions prepared by the ultrasonic dispersion of the N-CTs in silicone oil were measured. This showed that the N-CT suspensions possessed versatile ER performance including high ER efficiency, good dispersion stability, and temperature stability. Especially, compared to the corresponding heat treated granular PANI suspensions, the N-CT suspensions showed better dispersion stability and higher ER effect. Furthermore, the ER effect of N-CT suspensions could be adjusted by varying heat treatment temperatures and the N-CTs obtained at around 600°C exhibited the maximum ER effect. This could be explained by the polarization response, which originated from the regular change of conductivity of N-CTs as a function of heat treatment temperatures.

Fabrication and Characterization of Te/C Nanocables and Carbonaceous Nanotubes

In this Article, a green chemical synthetic route was developed to synthesize Te/C nanocables by using glucose as reducing agent and carbon source, Na2TeO3 as a tellurium source, and surfactant cet...

1D Tellurium Nanostructures: Photothermally Assisted Morphology‐Controlled Synthesis and Applications in Preparing Functional Nanoscale Materials

AbstractA facile visible‐light‐assisted solution‐phase approach has been successfully developed to synthesize trigonal Te 1D nanostructures. By varying the relative amount of H2TeO3 and water‐soluble polymers, wirelike, beltlike, tubular Te, and Te nanoparticle‐joined 1D aggregates, as well as a novel thorny 1D assembly of Te nanothreads can be synthesized on a large scale. The diameter of the Te nanowires can be modulated by controlling the nucleation and growth process through modulation of the pH value of the reaction mixture. It is believed that the light irradiation and thermal effect play a significant role in this photothermally assisted technique. We have shown that the Te nanowires can be used as a template to prepare Pt–Te nanochains, where the composition of Pt in the Pt–Te 1D products can be modulated by adjusting the ratio of the Te nanowires and Pt salts. Preliminary optical investigations reveal that blue–violet emission of Te nanowires can be enhanced by the formation of defects or dislocations in the Te region through the galvanic replacement reaction between Te nanowires and H2PtCl6. In addition, we demonstrate that Te 1D nanostructures can be utilized to prepare Te at carbon‐rich nanocables and carbonaceous nanotubes. Te–Pt at carbon‐rich nanocables can also be fabricated using Te–Pt nanochains as the template. These Pt–Te nanochains and carbonaceous nanostructures are expected to find wide applications in electrochemistry, catalysis, fuel cells, sensors, and other fields. Furthermore, the successful preparation of Te 1D nanostructures with abundant shapes, Pt–Te nanochains, and their carbonaceous composite nanomaterials will offer great opportunities to explore the dependence of novel properties of nanomaterials on their morphology and composition, regulate the photoconductivity of semiconductors, and also be essential for the manufacture of potential optoelectronic devices.

Fabrication and Characterization of Ultralong Ag/C Nanocables, Carbonaceous Nanotubes, and Chainlike β-Ag2Se Nanorods inside Carbonaceous Nanotubes

A novel complex-assisted hydrothermal route is presented to fabricate ultralong Ag/C nanocables with length ranging from 100 to 180 microm on a large scale, based on the reaction of sulfamic acid silver and salicylic acid. By chemical etching of these Ag/C nanocables, high-quality carbonaceous nanotubes can be obtained at room temperature. Using the as-prepared Ag/C nanocables as templates, a new strategy for introducing guest materials into hollow nanotubes is addressed. We take Ag(2)Se as an example and validate the feasibility of this strategy. All of the products are characterized in detail by multiform techniques: X-ray diffraction, Fourier transform IR, energy-dispersive X-ray analysis, field emission scanning electron microscopy, transmission electron microscopy (TEM), and high-resolution TEM. The formation mechanisms of these products are tentatively proposed.