硼掺杂对碳纳米管形貌和磁性能的影响

以碳纳米管为原料,利用真空封管技术在高温下用硼粉对碳纳米管进行掺杂处理,获得了碳化硼纳米管(纤维).利用透射电子显微镜、X射线衍射、X射线光电子能谱和磁性测试设备对样品的形貌、结构、组分和磁性能进行了表征.结果表明,掺硼后的碳纳米管(纤维)不仅在形貌上有很大改变,而且其磁性能也有了很大的改变.     

工业级原料制备碳纳米管的研究

为降低碳纳米管批量制备的原料成本,以焦化苯和二茂铁为主要原料(工业级),采用浮游催化热解法制备碳纳米管,用TEM、SEM、Raman、XRD等对产物的形貌和结构进行观察和表征,着重讨论了二茂铁的分解温度和苯的挥发温度对碳纳米管的制备及其形貌的影响,并对其影响机理进行了分析.研究表明:在噻吩体积分数为0.55 mL/100 mL苯、炉膛反应温度为1170℃的前提下,当二茂铁的分解温度为150℃、苯的挥发温度为50℃时,用工业级原料完全可以制备出碳纳米管,此时,碳纳米管的内径分布在0.88~1.15 nm.     

Facile synthesis of MnO2/CNT nanocomposite and its electrochemical performance for supercapacitors

A nanocomposite of manganese dioxide coated on the carbon nanotubes (MnO₂/CNTs) was synthesized by a facile direct redox reaction between potassium permanganate and carbon nanotubes without any other oxidant or reductant addition. The morphology, microstructure and crystalline form of this MnO₂/CNT nanocomposite were characterized by scanning electron microscopy (SEM), transition electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochemical properties are characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge (GCD). The results show that the facile prepared MnO₂/CNTs nanocomposite shows specific capacitance of 162.2 F g⁻¹ at the current density of 0.2 A g⁻¹ and excellent charge/discharge property with 90% of its specific capacitance kept after 2000 cycles at the current density of 5 A g⁻¹.     

Decoration of carbon nanotubes with nearly monodisperse MFe2O4 (MFe2O4, M = Fe, Co, Ni) nanoparticles

Magnetic monodisperse ferrite MFe₂O₄ (M = Fe, Co, Ni) nanoparticles have been successfully deposited on carbon nanotubes (CNTs) by in situ high-temperature hydrolysis and inorganic polymerization of metal salts and CNTs in polyol solution. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectrometry (EDS) and vibrating sample magnetometer (VSM) investigations were used to characterize the final products. The influencing factors for formation of CoFe₂O₄ nanoparticles along CNTs have also been discussed briefly. The main advantage of this synthetic strategy is that it is beneficial for the fabrication of magnetic CNTs with a compact layer of nanoparticles and could be extended to prepare series of ferrite/CNTs nanocomposites via the substitution of metal cations.     

Synthesis of carbon and carbon–nitrogen nanotubes using green precursor: jatropha-derived biodiesel

The jatropha-derived biodiesel, a green precursor was found to be a new and promising precursor for the synthesis of carbon nanotubes (CNTs) and carbon–nitrogen (C–N) nanotubes. The CNTs and C–N nanotubes have been synthesised by spray pyrolysis of biodiesel with ferrocene and ferrocene–acetonitrile, respectively, at elevated temperature under an argon atmosphere. The typical length and diameter of as-grown CNTs are 20?µm and 20–50?nm, respectively. The C–N nanotubes are found in bundles with effective length of ～30?µm and diameter ranging between 30 and 60?nm with bamboo-shaped morphology. The as-grown CNTs and C–N nanotubes were characterised through scanning and transmission electron microscopes, X-ray photoelectron, Raman and Fourier transform infrared spectroscopic techniques. These investigations revealed that the nanotubes synthesised by jatropha-derived biodiesel are clean from carbonaceous impurities and the bamboo compartment formations in C–N nanotubes are due to nitrogen incorporation. The nitrogen concentration in C–N nanotubes decreases with the increase in synthesis temperature.     

Structure and tensile properties of polypropylene/carbon nanotubes composites prepared by melt extrusion

Polypropylene/carbon nanotubes (PP/CNTs) nancomposites were prepared with a single screw extruder by adding maleic anhydride-grafted poplypropylene (PP-g-MAH) as compatibilizer to polypropylene (PP) with different amounts of carbon nanotubes (CNTs) in the range of 0.1–0.7 wt.%. Structure and morphology of the prepared samples were examined by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), polarizing light microscopy (PLM) and X-ray diffraction (XRD). The results showed that PP spherulites decreased in size when CNTs were introduced into the polymer. Mechanical properties of the samples were also studied. Tensile tests showed that with increasing amount of CNTs the strain at break decreased whereas the Young’s modulus was improved of 16.41 % to 36.05 % and tensile strength of 36.67 % to 64.70 % compared to pristine PP. The SEM microphotographs showed that majority of the CNTs were dispersed individually and oriented along the shear flow direction.     

Electrodeposited carbon nanotube thin films

A successful attempt to grow carbon nanotubes (CNTs) by electrodeposition technique for the first time is reported here. Carbon nanotubes were grown on Si (001) substrate using acetonitrile (1% v/v) and water as electrolyte at an applied d.c. potential ∼20 V. The films were characterized by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Raman, optical absorbance, Fourier Transform Infra Red spectroscopy (FTIR) and Electron Spin Resonance (ESR) measurements. The effect of magnetic field on the growth of nanotubes was studied critically. It was found that the presence of magnetic field during electro-deposition played a crucial role on the growth of carbon nanotubes and hence the electronic properties. Photoluminescence (PL) studies indicated band edge luminescence ∼0.72-0.83 eV. Field emission studies indicated lower turn-on voltage and higher current density for films deposited with magnetic field.     

化学气相沉积法合成碳纳米管及其导电性能研究

以二甲硫醚为碳源前驱体,Co/MgO为催化剂,采用化学气相沉积法生长出碳纳米管及Y形碳纳米管,此法稳定性及重现性较好.通过扫描电子显微镜、透射电子显微镜、拉曼光谱及X射线衍射对产品形态和结构进行了分析和表征,结果表明,所制备的碳纳米管形态较规整、纯度较高,具有较好的石墨微晶结构;导电性能测试结果显示,Y形碳纳米管各分支均呈现出典型的金属性导电性能.     

Efficient strategy to Cu/Si catalyst into vertically aligned carbon nanotubes with bamboo shape by CVD technique

Bamboo-shaped vertically aligned carbon nanotubes (bs-VACNTs) were fabricated on Cu/Si catalyst by chemical vapour deposition (CVD) technique under the atmospheric pressure. The catalytic material (Cu/Si) played a vital role in attaining bs-VACNTs, which is synthesized by drop cast method in a cost-effective manner. Using this catalytic support, we have achieved the tip growth bs-VACNTs at low temperature with well graphitization. The as-grown carbon material was then characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX) analyzer, high-resolution transmission electron microscope (HRTEM) and Raman spectroscopy. XRD technique confirms the formation of hexagonal graphitic carbon planes of carbon nanotubes (CNTs). The surface morphology of the material was characterized by SEM, which clearly infer vertically aligned CNTs. The nature, diameter and crystallinity were noticed by HRTEM and Raman spectroscopy, respectively. Further, we have also studied the electrochemical properties of the bs-VACNTs and it seems to be proved as highly electroconductive when compared to multi-walled carbon nanotubes (MWCNTs).     

Preparation and tribological properties of novel carbon nanotube self-assembled composite films

Carbon nanotube (CNT) composite thin films were prepared on a single-crystal silicon substrate by a self-assembling process from a specially formulated solution. Rare earth solution (RES) surface modification and appropriate acid-treatment methods were used to functionalise carbon nanotubes (CNTs). Silane coupling regent (3-mercaptopropyl trimethoxysilane (MPTS)) was prepared first. The terminal thiol groups (–SH) in the film was oxidised to sulphonic acid groups (–SO₃H) in situ to enhance the film with good chemisorption ability. Treated Caron nanotubes were deposited on the oxidised MPTS–SAM by means of chemisorption with the SO₃H group. The surface energy, chemical composition, phase transformation and surface morphology of the films were analysed using contact angle measurements, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and atomic force microscopy. As a result, a conclusion could be made that some lanthanum elements react with –SO₃H groups on the surface of the substrate by a chemical bond, which will improve the bonding strength between the films and the CNTs. Since the CNT thin films were well adhered to the silicon substrate, it might find promising application in the surface-modification of single-crystal Si and SiC in microelectromechanical systems (MEMS).     

新型一步法包裹Fe制备磁性碳纳米管

采用柠檬酸络合法制得不同 Fe 含量的 Fe/MgO 催化剂,并将其应用到气相沉积(CVD)过程中制备磁性碳纳米管。由 CVD 法制备碳纳米管(CNTs)的生长机理,利用碳管在生长过程中原位包裹磁性 Fe 金属氧化物颗粒进入管内的现象,使碳纳米管具有磁性,从而一步制得了磁性碳纳米管。将制得的磁性碳纳米管采用透射电子显微镜(TEM)、X 射线衍射仪(XRD)、红外光谱仪(IR)、低温 N2吸附仪(BET)、振动样品磁强计(VSM)等表征方法进行了测试。结果表明通过这种新型的一步法可以成功地原位包裹 Fe 制得碳纳米管,且制得的碳纳米管具有较强磁性和较大的比表面积,表面引入了功能化基团。     

Grafting carbon nanotubes onto carbon fiber by use of dendrimers

A novel method is developed for grafting carbon nanotubes (CNTs) onto the carbon fiber (CF) surface by use of dendrimers. CF surface is functionalized by an adsorbed dendrimers layer. After an oxidation treatment, CNTs with carboxyl, carbonyl or hydroxyl groups are grafted onto the amino-functionalized CFs via chemical interactions. Homogeneous multi-scale structures with different CNT densities and lengths are gained successfully. Functional groups and morphology of the resulting materials are examined by X-ray photoelectronspectroscopy (XPS), Fourier transform-infrared spectrometer (FTIR), and scanning electron microscopy (SEM).     

Coating carbon nanotubes with iron oxide using methanol-thermal reaction

Based on a methanol-thermal reaction method, coating carbon nanotubes (CNTs) with needle-like iron oxide has been achieved. The structure, composition and morphology of the coatings were characterized by using transmission electron microscopy, X-ray energy dispersive spectrum and X-ray photoelectron spectroscopy. The experimental results indicate that the pre-oxidation of CNTs and the acid-based methanol-thermal environment are very important points to obtain dense and uniform coatings on CNTs. Magnetic measurement for the iron oxide coatings indicates that the coercivity has been enhanced after coating.     

A study on the bactericidal properties of Cu-coated carbon nanotubes

A Cu layer was coated on carbon nanotubes (CNTs) by ion beam-assisted deposition (IBAD). Standard agar dilution method was used to evaluate the bactericidal rate against E. coli and S. aureus bacteria. The structure and chemical states of the Cu-coated CNTs were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results show that the Cu-coated CNTs possess a very high bactericidal rate. In comparison with the Cu-coated pyrolytic carbon sample, the Cu-coated CNTs show much stronger bactericidal property.     

碳纳米管/羟基磷灰石复合材料的制备及表征

以含钴介孔分子筛为催化剂、乙醇为碳源, 采用CVD法制备碳纳米管(CNTs)。通过原位合成法制备一系列不同碳纳米管含量的碳纳米管/羟基磷灰石(CNTs/HA)复合材料。分别采用XRD、FTIR、TEM、N₂吸附-脱附和Raman光谱等分析手段, 对所合成CNTs/HA复合材料的晶相、结构、形貌和比表面积等进行了表征。同时研究了碳纳米管的添加量对所合成CNTs/HA复合材料形貌的影响。XRD与Raman结果表明, 所得CNTs/HA复合粉体中仅有CNTs与HA两种物相, 纯度较高, 结晶度较好; TEM结果显示, CNTs/HA复合材料中CNTs表面均匀包裹着一层纳米级的针状HA晶粒, 两者形成了较强的界面结合, 且当CNTs与HA的质量比为3:17时, CNTs与HA形成最佳结合状态; N₂吸附-脱附表征结果表明, 与HA的比表面积相比, CNTs/HA复合材料具有较高比表面积。     

Improved filling rate and enhanced magnetic properties of Fe-filled carbon nanotubes by annealing and magnetic separation

The filling rate of Fe nanowires in carbon nanotubes (CNTs) was improved by a post-treatment which involved annealing and magnetic separation. The annealing process transformed γ-Fe to ferromagnetic α-Fe, resulting in α-Fe-filled CNTs with improved magnetic properties. The Fe-filled CNTs were then separated from those unfilled CNTs due to the different attractive forces under magnetic field. Thermal gravimetric analysis (TGA) revealed that the purity of CNTs was improved after magnetic separation and the filling rate can be up to 40.0 wt.%, which is increased about 8.1% comparing with annealed CNTs. The saturation magnetization of CNTs reached 31.45 emu/g after magnetic separation.     

碳纳米管改性泡沫镍/环氧树脂复合材料阻尼性能

采用一种新型简易的化学气相沉积法(CVD)直接在泡沫镍表面均匀地沉积生长碳纳米管(CNTs),然后通过真空导入模塑成型工艺(VIMP)将选定的环氧树脂体系填入表面负载CNTs的泡沫镍孔洞,制备CNTs-泡沫镍/环氧树脂复合材料。利用FE-SEM、TEM和Raman对在不同反应温度条件下泡沫镍表面形貌和所生成CNTs的形貌、结构及石墨化程度进行了表征,并采用动态机械分析仪(DMA)研究了CNTs对泡沫镍/环氧树脂复合材料阻尼性能的影响。结果表明:当反应温度为680℃时,在泡沫镍表面可获得较好的CNTs沉积效果,且所生成的CNTs石墨化程度和纯度较高且直径尺寸较为均匀。同时所制备的CNTs-泡沫镍/环氧树脂复合材料比泡沫镍/环氧树脂复合材料,最大损耗因子tanδ_(max)从0.69提高到0.78,玻璃化转变温度Tg从60℃偏移到68℃,有效阻尼温域ΔT从39℃扩宽到44℃,整体阻尼性能提高了18.9%。     

Effects of carbon nanotubes on electro-optical properties of dye-doped nematic liquid crystal

Electro-optical effects of planar nematic liquid crystal cells doped with dye and carbon nanotubes (CNTs) were investigated by utilizing the absorption property of the dye. Voltage-dependent transmittance and hysteresis measurements under applied ac and dc fields were presented. Cells doped with both Methyl Red and CNTs showed increased conductivity and capacitance, slower ac-rise switching time and dc-backflow on turn-off. The cells exhibited little hysteresis but those containing CNTs reduced residual dc by about 50%. First-order probe diffraction of permanent gratings revealed a correlation of ac-field-enhanced diffraction efficiency and Fréedericksz threshold voltage.     

Synthesis of nano-carbon (nanotubes,nanofibres, graphene) materials

In the present study, we report the synthesis of carbon nanotubes (CNTs) using a new natural precursor: castor oil. The CNTs were synthesized by spray pyrolysis of castor oil-ferrocene solution at 850°C under an Ar atmosphere. We also report the synthesis of carbon nitrogen (C-N) nanotubes using castor oil-ferrocene-ammonia precursor. The as-grown CNTs and C-N nanotubes were characterized through scanning and transmission electron microscopic techniques. Graphitic nanofibres (GNFs) were synthesized by thermal decomposition of acetylene (C₂H₂) gas using Ni catalyst at 600°C. As-grown GNFs reveal both planar and helical morphology. We have investigated the structural and electrical properties of multi-walled CNTs (MWNTs)-polymer (polyacrylamide (PAM)) composites. The MWNTs-PAM composites were prepared using as purified, with ball milling and functionalized MWNTs by solution cast technique and characterized through SEM. A comparative study has been made on the electrical property of these MWNTs-PAM composites with different MWNTs loadings. It is shown that the ball milling and functionalization of MWNTs improves the dispersion of MWNTs into the polymer matrix. Enhanced electrical conductivity was observed for the MWNTs-PAM composites. Graphene samples were prepared by thermal exfoliation of graphite oxide. XRD analysis confirms the formation of graphene.     

外贴Fe3O4/CNTs杂化碳纳米纸的碳纳米管复合材料吸波性能

通过对Fe₃O₄纳米粒子接枝碳纳米管的单分散水溶液真空吸滤制备出一种新型的杂化碳纳米纸, 它与树脂浸润良好, 可以与复合材料一体成型。分别借助FE-SEM、EDS、BJH法和振动样品磁强计表征杂化碳纳米纸及其复合材料的微观形貌、元素组成、平均孔径分布和磁性能。在8.2~18 GHz频段内利用波导法测量碳纳米管共混复合材料和外贴杂化碳纳米纸/碳纳米管共混复合材料的电磁参数和吸波反射率。研究结果表明: 外贴一层杂化碳纳米纸(厚0.1 mm)后, 碳纳米管共混复合材料的磁损耗明显增加, 在8.2~18 GHz微波频段内吸波反射率基本上全部小于-10 dB(频宽大于9.7 GHz), 在15.42 GHz位置, 反射损耗峰达-43.18 dB, 远优于碳纳米管共混复合材料。