Nitrogen-doped carbon nanotubes synthesized with carbon nanotubes as catalyst

Nitrogen-doped carbon (CN_x) nanotubes were synthesized with carbon nanotubes (CNTs) as catalyst by detonation-assisted chemical vapor deposition. CN_x nanotubes exhibited compartmentalized bamboo-like structure. Electron energy loss spectroscopy and elemental mapping studies indicated that the synthesized tubes contained high concentration of nitrogen (ca. 17.3 at.%), inhomogeneously distributed with an enrichment of nitrogen within the compartments. X-ray photoelectron spectroscopy analysis revealed the presence of pyridine-like N and graphitic N incorporated into the graphitic network. The catalytic activity of CNTs for CN_x nanotube growth was ascribed to the nanocurvature and opening edges of CNT tips, which adsorbed C_n/CN species and assembled them into CN_x nanotubes.     

机械混炼制备碳纳米管/天然橡胶复合材料特性分析

通过机械混炼方法将碳纳米管与天然橡胶复合，与炭黑补强样品相比，碳纳米管在橡胶中的混入速度快，功率消耗低，温升幅度小，混炼胶的硫化焦烧时间略有增加，硫化返原现象减轻，硫化剂用量应适当增加。加入碳纳米管后，橡胶DSC曲线中的结晶熔融峰面积减少，交联反应放热峰变宽。碳纳米管复合材料的回弹、压缩疲劳性能明显优于炭黑补强样品，耐老化性能较好，拉伸、撕裂性能水平有待提高。     

CNTs/PMS高级氧化体系去除水中的环丙沙星

针对当前抗生素废水处理的难题,以环丙沙星（CIP）为研究对象,采用碳纳米管（CNTs）活化过硫酸氢盐（PMS）对其进行降解。考察了PMS浓度、CIP浓度、CNTs投加量、初始pH等因素对CIP降解效果的影响。研究结果表明,在pH为2.73～11.38范围内,PMS的浓度为1.5mmol/L、CNTs投加量为15mg/L时,初始浓度为5mg/L的CIP降解效果达到最佳,CNTs在反应过程中集吸附和催化于一体,且作为催化剂可实现多次循环利用。借助电子顺磁共振捕获技术和自由基猝灭反应对降解过程中的活性物质进行分析与鉴定,实验结果表明,在整个反应体系中起主导作用的活性基团是硫酸根自由基（SO₄ ^?-）。通过中间产物分析,发现氧化反应主要发生在哌嗪基团、喹诺酮核心的C－F键及环丙烷环上。这些结果可应用于抗生素废水的工业处理。     

Sensing behaviors of polymer/carbon nanotubes composites prepared in reversed microemulsion polymerization

Polystyrene/carbon nanotubes composites were readily prepared by reversed microemulsion polymerization. Compared with the composites prepared by solution mixing, the uniform dispersion of carbon nanotubes in polymer matrix could be obtained more easily and the thermal and electrical properties of the as‐prepared composites were also enhanced. The as‐prepared composites were deposited onto a microelectrode array to fabricate a vapor sensor. The response for different organic vapors was evaluated by monitoring the change in the resistance of the composites upon exposure to various gases. The change in resistance was of the order of about 10³ for the composites prepared by reversed microemulsion polymerization. The chemical sensors based on the composites prepared by reversed microemulsion polymerization presented excellent reproducibility and reversibility in response. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Diameter control of single-walled carbon nanotubes by plasma rotating electrode process

We investigated plasma rotating electrode process (PREP) as a method for diameter control of single-walled carbon nanotubes (SWNTs) with a Ni–Y catalyst in He ambient. Compared with the diameters of SWNTs produced by the conventional arc discharge (0 rpm), those of SWNTs, which were synthesized by PREP (5000 and 10 000 rpm), were decreased. This result indicated that the centrifugal force by the rotation of anode could control the diameter distributions of SWNTs by controlling kinetic energies of carbon and/or metal species or formation region of SWNTs.     

Characterization of single wall carbon nanotubes by nonane preadsorption

The preferential blocking of the interior adsorption sites of single walled carbon nanotubes (SWNTs) by n-nonane is demonstrated. Following adsorption of n-nonane and evacuation for 24 h at 323 K, it was found that interior sites with diameters less than ∼14 Å remained filled with n-nonane, blocking the physical adsorption of N₂ on these sites at 77.3 K. We demonstrate that “nonane blocking” is a very useful technique for nanotube porosity characterization.     

煤基碳纳米管的制备

碳纳米管是一类新型纳米炭，具有很多潜在的应用价值，用煤为碳源制备碳纳米管可以降低其成本，本文介绍了电弧放电法和等离子体法制备煤基碳纳米管研究情况，以及相应的煤基碳纳米管生长机制。     

碳纳米管在电化学传感器中的应用进展

综述了碳纳米管(Carbon Nanotube,CNT)在电化学传感器研究中的应用进展。重点介绍了CNT电极和CNT修饰电极的制备、电化学特性及应用,并对其在DNA电化学生物传感器方面的应用前景与挑战进行了展望。     

Effect of pH on PtRu electrocatalysts prepared via a polyol process on carbon nanotubes

This paper reports a study on the pH effects on the PtRu nanoparticles synthesized in a polyol process that were deposited on carbon nanotubes (CNTs) by reducing metal salts using ethylene glycol at various pHs. It was found that the nanoparticle size, composition, and catalytic activity all were sensitive to pH. The nanoparticles decreased in size as the preparation pH increased from 1.6 to 10.0, with the largest size at 2.47 nm and the smallest at 1.13 nm. An exception was found for pH at 0.7, which resulted in an average size of only 1.01 nm. Preparation pH was found to affect polyol reaction mechanisms, which are believed to be dominated by direct metal reduction at low pH and by both direct metal reduction and hydroxide reduction at high pH. However, at high pH the reactions were limited by hydroxide reductions, and longer reaction durations were needed to fully deposit the metals. To study the pH effect on the electrochemical activity of the catalysts, CO stripping techniques were used to determine peak potentials and active surface areas. Together with cyclic voltammetry in the electro-oxidation of methanol, it was found that the catalyst prepared at pH 8.4 has the best performance.     

Melt mixing of carbon fibers and carbon nanotubes incorporated polyurethanes

Polyurethane composites filled with carbon fibers (CF) and carbon nanotubes (CNT) were prepared by mixing and injection molding, and its mechanical as well as their thermal properties were investigated. Dynamic mechanical analysis (DMA), thermogravimetry analysis (TGA), and thermal conductivity tests were done, and the properties were evaluated as a function of the filler concentration. The storage modulus of the composites increased with fillers concentration, which also mean the increase of the stiffness, suggest a good adhesion between the polyurethane matrix and the fillers. Addition of more CF and CNT to the composites broadened and lowered the peak of tan δ specifies that the polyurethane composite became more elastic because there is a good adhesion between the fillers and the matrix. The addition of carbon fillers improves the thermal stability of the polyurethane. The inclusions of CNT show a better thermal stability when compared with CF. The addition of carbon fillers also increased the thermal conductivity of the polyurethane composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

纳米碳管的制备及其应用

本文综述了纳米碳管的制备及应用,展望了纳米碳管广阔的应用前景。     

Processing and characterization of epoxy nanocomposites reinforced by cup-stacked carbon nanotubes

The effect of the dispersion, ozone treatment and concentration of cup-stacked carbon nanotubes on mechanical, electrical and thermal properties of the epoxy/CSCNT nanocomposites were investigated. Ozone treatment of carbon fibers was found to increase the surface oxygen concentration, thereby causing the contact angle between water, epoxy resin and carbon fiber to be decreased. Thus, the tensile strength, modulus and the coefficient friction of carbon fiber reinforced epoxy resin were improved. Moreover, the dispersion of fibers in polymer was increased and the electrical resistivity was decreased with the addition of filler content. The dynamic mechanical behavior of the nanocomposite sheets was studied. The storage modulus of the polymer was increased by the incorporation of CSCNTs. But the glass transition temperature decreased with increasing fiber loading for the ozone treated fiber composites. The ozone treatment did affect the morphology, mechanical and physical properties of the CSCNT.     

Co—Mo／MgO作催化剂CVD法制备碳纳米管

研究了催化剂的制备方法对合成碳纳米管的影响,分别采用溶胶凝胶法、浸渍法和燃烧法制备了Co-Mo／MgO催化剂,并以乙炔为碳源,Ar气为保护气,在750-950℃常压下生长碳纳米管。采用TEM对所得产物进行了表征,结果表明,对于Co-Mo／MgO体系,相对浸渍法和燃烧法,溶胶凝胶法是很好的选择,可以得到数量与质量均较好的碳纳米管,并讨论了溶胶凝胶法制备碳纳米管的过程中工艺参数的择优。     

Removal of nickel(II) from aqueous solution by carbon nanotubes

Single‐walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) were oxidized by NaClO solutions and were employed as sorbents to study sorption characteristics of nickel(II) from aqueous solution. The surface properties of CNTs such as functional groups, total acidic sites and negatively charged carbons were greatly improved after oxidation, which made CNTs become more hydrophilic and resulted in sorption of more Ni²⁺. The amount of Ni²⁺ sorbed onto oxidized CNTs increased with a rise in agitation speed, initial Ni²⁺ concentration and solution pH in the range 1–8, but decreased with a rise in CNT mass and solution ionic strength. The sorption mechanisms are complicated and appear attributable to electrostatic forces and chemical interactions between the Ni²⁺ and the surface functional groups of the CNTs. The oxidized SWCNTs and MWCNTs have shorter equilibrium time and better Ni²⁺ sorption performance than the oxidized granular activated carbon, suggesting that both NaClO oxidized CNTs are efficient Ni²⁺ sorbents and that they possess good potential applications in water treatment. Copyright © 2006 Society of Chemical Industry     

Fabrication of carbon nanotubes/polypyrrole/carbon nanotubes/melamine foam for supercapacitor

The carbon nanotubes (CNTs) have been loaded on the melamine foam (MF) to form the composite (CNTs/MF) by dip‐dry process, then polypyrrole (PPy) is coated on CNTs/MF (PPy/CNTs/MF) through chemical oxidation polymerization by using FeCl₃·6H₂O adsorbed on CNTs/MF as oxidant to polymerize the pyrrole vapor. Finally, CNTs are coated on the surface of PPy/CNTs/MF to increase the conductivity of the composite (CNTs/PPy/CNTs/MF) by dip‐dry process again. The composites have been characterized by X‐ray diffraction spectroscopy, scanning electron microscopy and electrochemical method. The results show that the structure of the composites has obvious influence on their capacitive properties. According to the galvanostatic charge/discharge test, the specific capacitance of CNTs/PPy/CNTs/MF is about 184 F g^?1 based on the total mass of the composite and 262 F g^?1 based on the mass of PPy (70.2 wt % in the composite) at the current density of 0.4 A g^?1, which is higher than that of PPy/CNTs/MF (120 F g^?1 based on the total mass of the composite and 167 F g^?1 based on the mass of the PPy). Furthermore, the capacitor assembled by CNTs/PPy/CNTs/MF shows excellent cyclic stability. The capacitance of the cell assembled by CNTs/PPy/CNTs/MF retains 96.3% over 450 scan cycles at scan rate of 20 mV s^?1, which is larger than that assembled by CNTs/PPy/MF (72.5%). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39779.     

Synthesis of carbon nanotubes on carbon fibers by means of two-step thermochemical vapor deposition

The present study aimed at development of a method for synthesizing multi-walled carbon nanotubes (CNTs) on carbon paper substrates (CP) at densities as high as those so far reported for CNTs formed on quartz substrates. Applying conditions optimized for CNTs synthesis on quartz substrates, in which CP was heated at 1073 K, being placed parallel to the flow of m-xylene/ferrocene vapor, resulted in formation of extremely few deposits on CP. Forced vapor flow through the CP greatly improved the frequency and homogeneity of deposition of the Fe-bearing nanoparticles, but these became encapsulated by carbon and deactivated. The addition of H₂S to the vapor further enhanced nanoparticle deposition. Moreover, it enabled the subsequent formation of CNTs at densities as high as 2-6 × 10⁹ cm⁻². In order to realize such high population densities, it was found essential to perform CVD in a two-stage sequence commencing with nanoparticles deposition at 1073 K followed by the formation and growth of CNTs at 1273 K, with the H₂S concentration in the vapor phase optimized throughout within a range of 0.014-0.034 vol%.     

Adsorption of fulvic acids from aqueous solutions by carbon nanotubes

Carbon nanotubes (CNTs) were used as adsorbent to remove fulvic acids (FA) from aqueous solutions. The adsorption capacity of CNTs for FA can reach 24 mg g^?1 at 5 °C and equilibrium concentration of 18 mg dm^?3. The kinetic and thermodynamic parameters, such as rate of adsorption, standard free energy changes (ΔG⁰), standard enthalpy change (ΔH⁰) and standard entropy change (ΔS⁰), have been obtained. Acidic conditions (pH = 2–5) favor FA removal. An increase in the ionic strength or the addition of divalent cations increase the adsorption of FA dramatically (FA = 60 mg dm^?3). An increase in the maximum adsorbed amount of FA was observed when treating FA in synthetic seawater. Desorption studies reveal that FA can be easily and quickly removed from CNTs by altering the pH values of the solution. Good adsorption capacity and quick desorption indicate that CNTs are a promising adsorbent to remove FA from aqueous solutions. Copyright © 2007 Society of Chemical Industry