Multilayer Carbon Nanotubes Research Articles

Multiwalled carbon nanotube and graphene–polystyrene nanocomposites for bolometric detection

In this paper, the authors report on the use of multilayered carbon nanotubes and graphene films for the fabrication of temperature sensitive resistors. Multiwalled carbon nanotubes- and graphene-based films possess moderate temperature coefficients of resistance and wideband infrared absorption efficiency. This work demonstrates that by incorporating these nanoparticles into a thermally and electrically insulating polymer, polystyrene, the temperature sensitivity significantly improves. Experimental results show temperature coefficients of resistances for these films as high as −0.7%/K. The layers were deposited using a spraying setup without further chemical or thermal treatment. The low cost, simple, and versatile deposition process, in addition to the high temperature coefficients of resistances for these films, makes them suitable alternatives for infrared image sensors as well as many other sensing applications.

Modification of Multilayer Carbon Nanotubes for the Removal of Arsenate.

The aim of this study was to explore a new nano-composite carbon adsorbent material for the removal of arsenic from water. The multilayer carbon nanotubes (MCNTs) were treated with different acids and/or modified with iron to create more surface COOH sites or Fe-impregnated MCNTs for the enhanced uptake of As(V). Tests were conducted as a function of initial As(V) concentrations, contact time, and solution pH. The coverage of ferric hydroxides on MCNTs and the uptake of As on Fe-MCNTs were independently confirmed by field emission scanning electron microscope and energy dispersive X-ray spectroscopy analyses. With an As(V) uptake capacities of 27 mg/g on Fe-MCNTs and 14 mg/g on acid-MCNTs, the material showed superior performance for As(V) removal.

Analysis of the Formation of Multi-Layer Carbon Nanotubes in the Process of Mechanical Activation of the Pyrolysis Products of Vegetable Raw Materials

The carbon nanotubes are formed by pyrolytic and mechanochemical technology. Amorphous carbon is produced at 950°C and then subjected to mechanochemical treatment in a planetary mill for 1–46 h. Analysis ofinfluence of duration of mechanical activation of amorphous carbon on the morphology of moldable multilayer carbon nanotubes. It is demonstrated that prolonged mechanical activation of carbon composite in a vario-planetary mill promotes to formation of aggregates and amorphous carbon and to loss of thermal stability of nanotubeswith furtherconduct of vacuum annealing.

Study of multilayer carbon nanotubes subjected to the impact of a nanosecond high-energy ion beam

The impact of a nanosecond high-energy ion beam on the structure and morphology of multilayer carbon nanotubes and their ensembles is studied using transmission electron microscopy and scanning electron microscopy. It is shown that ion-beam irradiation leads to a decrease in the outer diameters of carbon nanotubes, which is related to the destruction of their outer layers. In addition, the secondary growth of carbon nanotubes with smaller diameters and the growth of bulblike formations, inside which structures with interplanar distances that are close to those of nanodiamond are fixed, are observed.

Catalytic Methods for Preparation of Composites Based on Polyethylene and Multilayer Carbon Nanotubes

Analytic consideration was focused on the efficiency of methods for the introduction of multilayer carbon nanotubes (MCNT) to polymer composites based on polyethylene (PE) and ultrahigh molecular weight polyethylene (UHMWPE). The methods under consideration were: (1) mechanical mixing of MCNT and a polymer melt; (2) ethylene polymerization over a disperse titanium-magnesium catalyst (TMC) in the presence of MCNT; (3) ethylene polymerization over a TiCl 4 catalyst which was pre-anchored on the MCNT surface. MCNT/PE and MCNT/UHMWPE composites with different MCNT contents (3,5 to 19 wt.%) were prepared at varying the polymerization conditions, and their properties (uniformity of MCNT distribution through the polymer, molecular-mass characteristics, viscosity, fluidity, electrical conductivity) were characterized. The most uniform distribution was shown to achieve when ethylene is polymerized over the catalyst anchored directly to the nanotube surface (method 3). Method 1 is only of limited use in preparation of MCNT/UHMWPE because of the high viscosity of UHMWPE. Practically identical molecular weights are characteristic of polymers are obtained upon ethylene polymerization over the TMC catalysts and over catalysts anchored on MCNT. The proper choice of the catalytic system and polymerization conditions makes it possible to synthesize MCNT/PE composites with the required polymer properties.

Increased durability concrete for generation of pillars power lines

In this researches multilayered carbon nanotubes of production of the French corporation “Arkema” were used. It has followed features: diameter of 10-15 nanometers and up to 15 microns long. Multilayered carbon nanotubes were used for increasing of physics and technology properties of cement concrete. It was established that at introduction of multilayered carbon nanotubes in amount of 0.006% of the mass led concrete durability increases by 28%, resistance to frost from F200 to F400, tightness to water from W8 to W14.

Superficial and electrical characterization of thin films based on Chitosan/polypyrrole/MWCNT

ABSTRACTIn recent decades conducting polymers have attracted attention due to their promising and versatile applications in different fields. There is a considerable interest in the application of nanotubes multilayer carbon (MWCNT) because of their unique structure, high electrical conductivity, high chemical stability, and high surface-to-volume ratio. These properties make MWCNT extremely attractive for fabricating sensors. Composites based on a matrix of a biopolymer such as the chitosan (CS) with a lot of conductive polymers or (MWCNT), have received increasing attention due to their attractive structural, mechanical and electrical properties that could have applications in different fields such as tissue engineering, biomedicine, and manufacture of sensors and biosensors. Have been reported conducting polymer composites with an extensive range of interesting mechanical and electrical properties, which is reported in this paper to obtain films by ultrasonic bath mixing of Chitosan 3% w/v using polypyrrole (PPy) and multilayer carbon nanotubes. Surface characterization was performed using scanning electron microscopy (SEM). The electrical properties were analyzed using electrochemical impedance spectroscopy (EIS) in a frequency range 0.01 - 10E+5 Hz to 10 mV AC. The results show that the films of CS/PPy/MWCNT have a homogeneous distribution where the chitosan envelops the loads, while for EIS retention load was observed within the matrix observing these materials in accordance with the equivalent circuit of Warburg showing diffusional process.

Non-covalent functionalisation of carbon-based nanostructures and its application to carbon/epoxy composites

This research goal is to investigate the surfactant effects on carbon/epoxy composites nano-modified by graphene and carbon nanotubes (CNTs). Multi-layered graphene (MLG) and multiwall carbon nanotubes were dispersed with two different surfactants, one ionic and another non-ionic, i.e., sodium dodecylbenzenesulfonate (SDBS) and polyoxyethylenenonylphenyl ether (IGEPAL® CO-890). The nanoscale analysis was based on morphological/nature observations via scanning electron microscopy (SEM) and atomic force microscopy (AFM), while the macro analysis follows the mechanical characterisation by tensile tests (ASTM D 3039) and three point bending test (ASTM D 790). The usage of surfactants as a strategy to improve the bonds between the nanostructures themselves, i.e., MLG and MWNT, and/or polymeric chains seems to be a viable option. However, in both cases, tensile and bending tests, the stiffness seems to be insensitive to non-covalent functionalised nanostructures. The ultimate strength, on the other hand, appears to be affected by the usage of surfactants (either CO890 or SDBS). The non-ionic CO890 surfactant seems to be more effective with MLG and pristine MWNT. In this case, for tensile tests the increase was close to 23.5%, while for bending tests an improvement of 11.4% was observed.

Silver nanoparticle decorated polyaniline/multiwalled super-short carbon nanotube nanocomposites for supercapacitor applications

In order to increase the utilization of the closed pore volumes of CNTs, multilayer super-short carbon nanotubes (SSCNTs) have been synthesized by tailoring the raw multiwalled carbon nanotubes (MWCNTs) with a simple ultrasonic oxidation-cut method.

Excellent heat dissipation properties of the super-aligned carbon nanotube films

Excellent heat dissipation properties of multilayer super-aligned carbon nanotube films were measured and a novel CNT CPU-radiator was proposed.

From graphene to carbon nanotube: The oxygen effect on the synthesis of carbon nanomaterials on nickel foil during CVD process

In this study, we demonstrated an oxygen-assisted ultralow-pressure (20 mTorr) chemical vapor deposition (CVD) method for the synthesis of carbon nanomaterials, including multilayer graphene (MLG), double-layer graphene (DLG), single-layer graphene (SLG), and carbon nanotubes (CNTs) on a Ni foil substrate. Oxygen is typically considered undesirable to synthesize carbon nanomaterials during the CVD process. However, our study provided evidence demonstrating that the growth of MLG, DLG, SLG, and CNTs can be maintained by adjusting the oxygen concentration during the CVD process; it also provided an easy way in controlling the layer of graphene. It was observed that oxygen played an important role in controlling the synthesis of carbon nanomaterials.

Influence of Duration of Mechanical Activation of Plant Material Pyrolysis Products on Thermal Stability of Moldable Multilayer Carbon Nanotubes

The influence of duration of mechanical activation of amorphous carbon produced by plant material pyrolysis on the morphology of moldable multilayer carbon nanotubes is studied. The maximum nanotube yield is observed when amorphous carbon is mechanically activated for 36 hours. The nanotube yield depends a great deal on the type of plant materials submitted to pyrolysis. It is demonstrated that prolonged mechanical activation of carbon composite in a vario-planetary mill leads to formation of aggregates consisting of multilayer nanotubes and amorphous carbon and to loss of thermal stability of nanotubes. This fact is responsible for the decrease in carbon nanotube content in products of vacuum annealing carried out for nanotube purification.

An Investigation of the Possibility of Using Nickel-Activated, Multilayer Carbon Nanotubes in Catalyst Development

An Investigation of the Possibility of Using Nickel-Activated, Multilayer Carbon Nanotubes in Catalyst Development

Multilayer Graphene Nanoribbon and Carbon Nanotube Based Floating Gate Transistor for Nonvolatile Flash Memory

Floating gate transistor is the fundamental building block of nonvolatile flash memory, which is one of the most widely used memory gadgets in modern micro and nano electronic applications. Recently there has been a surge of interest to introduce a new generation of memory devices using graphene nanotechnology. In this article, we present a new floating gate transistor (FGT) design based on multilayer graphene nanoribbon (MLGNR) and carbon nanotube (CNT). In the proposed FGT, a MLGNR structure would be used as the channel of the field effect transistor (FET) and a layer of CNTs would be used as the floating gate. We have performed an analysis of the programming and erasing mechanism in the floating gate and its dependence on the applied control gate voltages. Based on our analysis we have observed that proposed graphene based floating gate transistor could be operated at a low voltage compared to conventional silicon based floating gate devices. We have presented detail analysis of the operation and the programming and erasing processes of the proposed FGT; the dependency of the programming and erasing current density on different parameters; and the impact of scaling the thicknesses of the control and tunneling oxides. To perform these analyses we have developed equivalent models for device capacitances.

Electrochemical determination of Cu(II) ions using glassy carbon electrode modified by some nanomaterials and 3-nitroaniline

Abstract The aim of this research was to investigate the effect of the several nanomaterials in electrochemical determination of Cu(II) ions. For this aim, firstly the deposition of graphene oxide (GO), graphene, magnetite (Fe3O4), gold-chitosan (AuChts) or multilayer carbon nanotubes (MWCNTs) on the glassy carbon (GC) electrode surface was performed. Then the electrochemical modification of electrode by poly-3-nitroaniline (poly-3NA) was performed by 100 potential cycles in the range between +0.9 V and +1.4 V vs. Ag/AgNO3 at the sweep rate of 100 mV/s. For electrochemical reduction of nitro groups present on modified GC electrode surface, potential cycling was performed in 100 mM HCl between −0.1 V and −0.8 V vs. Ag/AgCl/(KClsat.) at the sweep rate of 100 mV/s. Nanomaterial and poly-3NA modified electrodes were applied in the determination of Cu(II) ions by differential pulse voltammetry. It was determined that GC electrodes consecutively modified with MWCNTs, poly-3NA and then by electrochemical reduction of nitro groups were the most sensitive towards Cu(II) ions with detection limit of 0.5 × 10−9 M.

Comparative studies of singlet oxygen generation by fullerenes and single- and multilayer carbon nanotubes in aqueous suspensions

Singlet oxygen generation is studied in three types of carbon nanoparticles (C60 fullerene and single- and multilayer carbon nanotubes in the form of aqueous suspensions obtained by sonication) upon their irradiation by continuous-wave broadband visible radiation of light-emitting diodes.

Comparative studies of singlet oxygen generation by fullerenes and single- and multilayer carbon nanotubes in the form of solid-phase film coatings

Four types of carbon nanoparticles: C60 fullerene (crystalline and amorphized) and single- and multilayer carbon nanotubes were studied in the form of solid-phase film coatings for the purpose of obtaining singlet oxygen generation in the process of irradiation of these materials by continuous-wave broadband light-emitting diodes in the visible region spectra and by a monopulse 532-nm neodymium laser.

Thermodynamic characteristics of the adsorption of oxygen by multilayer carbon nanotubes

Results from studying the adsorption of nitrogen and oxygen by multilayer carbon nanotubes are presented for a wide range of varying of experimental conditions (gas pressure, sorbent temperature, adsorption time). Characteristic values for the heat of adsorption, specific surface, volume and size of pores, and energy of adsorption are determined using experimental data on the studied adsorbents.

Modification of Fe–Cu–Co–Sn–P metal matrix with various forms of carbon nanomaterials

The opportunity of the powdered Fe–Cu–Co–Sn–P system alloy modification with multilayer carbon nanotubes (MCNT), fullerenes, nano- and ultra- sized diamonds for the purpose of composite material development with elevated mechanical properties, which can be used as bond for diamond cutter tools, has been considered. As a result of the spent experiments it is determined that the material containing 0,01 % MCNT possesses the best complex of mechanical properties: hardness increases by 14 HRB, three-point bending strength up to 40 % (in comparison with initial alloy). The exe- cuted bench tests of diamond drills have shown tool-life gain up to 40 % with simultaneous increase in productivity up to 50 %.

Fabrication Of Carbon Nanoribbons Via Chemical Treatment Of Carbon Nanotubes And Their Self-Assembling.

ABSTRACTSome potential applications of the nanoribbons and nanorods occur in the medical field, using gold nanoribbon therapies against cancer cells because they have absorption in the near infrared region. In this paper, the nanoribbons were obtained by physical-chemical method based on multilayer carbon nanotubes functionalized with carboxylic radical groups (-COOH). The obtained material was characterized by Scanning Transmission Electron Microscopy (STEM) and Infrared Spectroscopy (FTIR). The obtained nanoribbons have a diameter of 320 nm with preferably 126° angle in their morphology.