Thermal Oxidation of a Carbon Condensate Formed in High-Frequency Carbon and Carbon–Nickel Plasma Flow

We have reported on the comparative characteristics of thermal oxidation of a carbon condensate prepared by high-frequency arc evaporation of graphite rods and a rod with a hollow center filled with nickel powder. In the latter case, along with different forms of nanodisperse carbon, nickel particles with nickel core–carbon shell structures are formed. It has been found that the processes of the thermal oxidation of carbon condensates with and without nickel differ significantly. Nickel particles with the carbon shell exhibit catalytic properties with respect to the oxidation of nanosized carbon structures. A noticeable difference between the temperatures of the end of the oxidation process for various carbon nanoparticles and nickel particles with the carbon shell has been established. The study is aimed at investigations of the effect of nickel nanoparticles on the dynamics of carbon condensate oxidation upon heating in the argon–oxygen flow.     

Nanoscale Lasers Based on Carbon Peapods

A scheme of nanoscale lasers based on the so-called carbon peapods is examined in detail. Since there is considerable cylindrical empty space in the middle of a single-wall carbon nanotube （SWCNT）, it can serve as a laser resonant cavity that consists of two highly reflecting alignment ＂mirrors＂ separated by a distance. These mirrors refer to the ordered arrays of C6o inside SWCNTs, which have photonic bandgap structures. Meanwhile, ideally single-mode lasers are supposed to be produced in the nanoscale resonant cavity.     

Carbon–ionic liquid double-layer capacitors

A series of electrochemical capacitors, based on activated carbon powders (ACP, specific surface area 870 and 2600 m²/g) and ionic liquids as electrolytes, were prepared and tested. The ionic liquids consisted of 1-ethyl-3-methyl imidazolium (EMIm⁺), 1-butyl-3-methyl imidazolium (BMIm⁺) and 1-methyl-1-propyl pyrrolidinium (BMPy⁺) cations, as well as of tetrafluoroborate, hexafluorophosphate and bis((trifluoromethyl)sulfonyl) imide anions. A typical capacitor consisted of two electrodes each with a mass of ca. 15–30 mg, and showed a capacity of ca. 0.35–1.5 F; this leads to a specific capacity of the carbon electrode material within the range of 45 (ACP 870 m²/g)–180 F/g (ACP 2600 m²/g). The specific capacity expressed versus total surface of carbon material was within the range of 5.2–6.9 μF/cm². The electrochemical stability window of ionic liquids determined at the glassy carbon electrode is within the range of ca. 3.0–4.2 V. The energy stored in a capacitor based on activated carbons and ionic liquids may be high, due to a broad practical electrochemical stability window of ca. 3 V. Ionic liquids are characterised by negligible vapour pressure; such a capacitor emits no volatile organic compounds and may be regarded as environmentally friendly.     

Carbon nanotube emitters and field emission triode

Based on our study on field emission from multi-walled carbon nanotubes (MWNTs), we experimentally manufactured field emission display (FED) triode with a MWNTs cold cathode, and demonstrated an excellent performance of MWNTs as field emitters. The measured luminance of the phosphor screens was 1.8 × 103 cd/m2 for green light. The emission is stable with a fluctuation of only 1.5% at an average current of 260 μA.     

Dependence of In—Tube Carbon Chain on the Radius and Helicity of Single—Wall Carbon Nanotubes

Using the Lannard-Jones interaction potential,we have studied the in-tube carbon-chain structure doped into single-wall carbon nanotubes (SWCNTs).Through minimizing the potential energy of the doped system,it is found that the optimal structure of the doping carbon chain is spiral,but not a straight line,when the radius of the SWCNT is larger than about 4.30A.     

Hopping Conductivity in a Single-Walled Carbon Nanotube Network

We investigate the resistance and magnetoresistance （MR） of an entangled single-walled carbon nanotube （SWNT） network. The temperature dependence of conductance is fitted by formula G（T） = Go exp[-（To/T）^1/2] with To = 15.8 K at a wide temperature range from 4 K to 300K. The MR defined by [R（T, H） - R（T, 0）]/ R（T, 0） as a function of temperature and magnetic field perpendicular to the tube axis is negative at low temperatures. The MR amplitude increases as the temperature decreases at relative high temperature, but becomes decrease when temperature below 4 K. The results are explained in terms of the coherent hopping of carriers in the presence of a Coulomb gap at low temperature.     

Nodular Carbon Nanotubes and Their Field Emission Characteristics

A new configuration of carbon namotubes(CNTs) has been discovered in our laboratory and their surfaces are fully covered with nano-sized node-like structures.The node structures have almost the same size of 40-50nm.We refer to this material as the nodular carbon nanotube (NCNT).Field emission scanning electron microscopy shows that after a hydrogen plasma process in our homemade plasma equipment,the common carbon nanotubes were changed into NCNTs.The experimental result demonstrates that this material has good field emission characteristics,low threshold field,stable and suitable emitting surrent,especdially for the emission site density up to the order of 10^6cm^-2.     

Electrical Resistance Measurement of an Individual Carbon Nanotube

Aiming at the difficulty in the electrical resistance measurement, we develop a simple statistical model for the carbon nanotubes adequately dispersed in available insulated liquid and introduce the concept of “the most probability”. Based on this model, we obtain the function between macroscopic resistance R and resistance of an individual nanotube, Ro, from which one can calculate the resistance of an individual nanotube by measuring the macroscopic resistance. By computational simulation, we prove the reliability of the model. Then, we analyse the feasibility of the model when applied to experiment.     

Carbon nanotube–ZnO nanocomposite electrodes for supercapacitors

Carbon nanotube (CNT)–zinc oxide (ZnO) nanocomposite and gel poly(vinyl alcohol)–phosphomolybdic acid were employed as the electrode and electrolyte of the experimental supercapacitor cell, respectively. The ZnO nanodots were deposited onto CNT films by ultrasonic spray pyrolysis in different times. The results of electrochemical measurements showed that the electrode with ZnO deposited in 5 min had the optimal capacitive properties among the experimental series, with a lowest interfacial electron transfer resistance, a very high capacitance of 323.9 F/g and good reversibility in the repetitive charge/discharge cycling test.     

Single-Walled Carbon Nanotubes Acting as Controllable Transport Channels

The motion and equilibrium distribution of water molecules adsorbed inside neutral and negatively charged singlewalled carbon nanotubes (SWNTs) have been studied using molecular dynamics simulations (MDSs) at room temperature based on CHARMM (Chemistry at HARvard Molecular Mechanics) potential parameters. We find that water molecules have a conspicuous electropism phenomenon and regular tubule patterns inside and outside the charged tube wall. The analyses of the motion behaviour of water molecules in the radial and axial directions show that by charging the SWNT, the adsorption efficiency is greatly enhanced, and the electric field produced by the charged SWNTs prevents water molecules from flowing out of the nanotube. However, water molecules can travel through the neutral SWNT in a fluctuating manner. This indicates that by electrically charging and uncharging the SWNTs, one can control the adsorption and transport behaviour of polar molecules in SWNTs for using as a stable storage medium or long transport channels. The transport velocity can be tailored by changing the charge on the SWNTs, which may have a further application as modulatable transport channels.     

Deterioration of the Strong sp2 Carbon Network in Carbon Nanotubes during the Mechanical Dispersion Processing—A Review

The unique mechanical, thermal, and electrical properties of carbon nanotubes (CNTs) make them an ideal reinforcement for the metal matrix composites (MMCs). The successful incorporation of CNTs as reinforcement in MMCs can result in the development of lightweight and high-strength structures which can eventually result in weight savings for the automobile and aerospace industries. In the last two decades extensive research has been carried out to improve the dispersion of CNTs in metal and polymer matrices. Challenges remain to effectively disperse CNTs within the matrix materials with minimal damage during the composite processing stages. The ultra-high Young's modulus and other superior mechanical and thermal properties of CNTs have been attributed to the strong sp² A. M. Esawi and M. A. El Borady, Carbon nanotube-reinforced aluminium strips. Compos. Sci. Technol. 68, 486 (2008).[Crossref], [Web of Science ®] , [Google Scholar] carbon-carbon (C-C) bonds present in their structures. In order to fully utilize the unique properties of CNTs as reinforcement, damages to CNTs in the form of damaging these sp²C-C bonds have to be minimized. A variety of processing techniques have been developed to fabricate CNTs reinforced MMCs but mechanical alloying (MA) via powder metallurgy (PM) is most widely used process to develop the nano-composites. The role of processing variables during PM and their effects on the structural integrity of CNTs have been reviewed in this work. Governing principles to predict the mechanical properties of CNTs with incorporating the key process variables are deduced. With the help of these governing equations, critical study of the processes parameters and their effects on the structural integrity of CNTs, it is possible to optimize the processing methodologies of CNTs reinforced MMCs and get the maximum benefit from the unique properties of CNTs. It is assumed that better dispersion of CNTs in the metal matrices, retaining the structural integrity of CNTs and optimization of process parameters would result in better mechanical and tribological properties of CNTs reinforced MMCs.     

Low-Field Emission from Iron Oxide-Filled Carbon Nanotube Arrays

Arrays of multi-walled carbon nanotubes (MWCNTs) filled with iron oxide have been fabricated by a one-step route based on the pyrolysis of ferrocene under a well-chosen synthesis condition. The MWCNT arrays were observed with a scanning electron microscope, with which an energy dispersive x-ray spectrum (EDXS) was also acquired, and they are analysed by x-ray diffraction. Furthermore, individual MWCNTs were studied by using selected area electron diffraction (SAED) and the EDXS in a transmission electron microscopy observation. All the observation and analysis confirmed that the MWCNTs were filled with iron oxide. Field emission from these arrays of iron oxide-filled MWCNTs was measured and the turn-on field was determined to range from 0.83-1.01 V/μm, appearing to be much lower than those of arrays of pure MWCNTs and arrays of nitrogen-doped MWCNTs fabricated in similar ways. The possible reasons of the observed low-field emission are discussed.     

Mössbauer Study of Iron-Containing Carbon Nanotubes

⁵⁷Fe transmission Mössbauer at temperatures between 18 and 298 K and magnetic measurements have been used to characterize Fe-filled carbon nanotubes which were prepared by pyrolisis of Ferrocene + C₆₀ at atmospheric pressure under an Ar atmosphere at 1050°C. The Mössbauer data have shown that the Fe phases encapsulated within the carbon nanotubes are -Fe, Fe₃C and -Fe. The magnetic results are compatible with the Mössbauer data. Taken together the results allow us to propose a simple picture of the distribution of iron phases within the carbon nanotubes which would consist of an -Fe core surrounded by an -Fe shell, finally covered by an Fe₃C layer.     

High Energy Density Polymeric Nitrogen Nanotubes inside Carbon Nanotubes

Polymeric nitrogen as a new class of high energy density materials has promising applications. We develop a new scheme of crystal structure searching in a confined space using external confining potentials fitted from firstprinciples calculations. As a showcase, this method is employed to systematically explore novel polymeric nitrogen structures confined in single-walled carbon nanotubes. Several quasi-one-dimensional single-bonded polymeric nitrogen structures are realized, two of them are com...     

Hydrogen Storage in Benzene Moiety Decorated Single-Walled Carbon Nanotubes

The hydrogen storage capacity of （5, 5） single-walled carbon nanotubes （SWNTs） decorated chemically with benzene moieties is studied by using molecular dynamics simulations （MDSs） and density functional theory （DFT） calculations. It is found that benzene molecules colliding on （5, 5） SWNTs at incident energy of 50eV form very stable configurations of benzene moiety adsorption on the wall of SWNTs. The MDSs indicate that when the benzene moiety decorated （5, 5） SWNTs and a pristine （5, 5） SWNT are put in a box in which hydrogen molecules are filled to a pressure of ～26 atm, the hydrogen storage capacity of the benzene moiety decorated （5, 5） SWNT is about 4.7wt.% and that of the pristine （5, 5） SWNT is nearly 3.9wt.%.     

Ab Initio Calculation on Self-Assembled Base-Functionalized Single-Walled Carbon Nanotubes

We perform ab initio calculations on the self-assembled base-functionalized single-walled carbon nanotubes （SWNTs） which exhibit the quasi-1D ‘ladder＇ structure. The optimized configuration in the ab initio calculation is very similar to that obtained from molecular dynamics simulation. We also calculate the electronic structures of the self-assembled base-functionalized SWNTs that exhibit distinct difference from the single-branch base-functionalized SWNT with a localized state lying just below the Fermi level, which may result from the coupling interaction between the bases accompanied by the self-assembly behaviour.     

Structure Stability of I—Type Carbon Nanotube Junctions

Carbon nanotubes with junctions may play an important role in future nanoelectronics and future nano devices.In particular,junctions constructed with metal and semiconducting nanotubes have potential applications.Based on the orthogonal tight-binding molecular dynamics method,we present our study of the structure stability of I-type carbon nanotube junctions.     

Strain Induced Insulator-Metal Transition in Single Wall Carbon Nanotubes

In terms of a single-π orbital model, an analytical expression of the lowest-lying conduction-band and the highestlying valence-band is derived for single wall carbon nanotubes under both the uniaxial and torsional strains. We observe not only semiconductor-metal transitions in primary metallic tubes, but also insulator-metal transitions