Dielectrophoretic assembly of semiconducting single-walled carbon nanotube transistor

A novel burning technique for making a semiconducting single-walled carbon nanotubes (SWNTs) transistor assembled by the dielectrophoretic force was suggested. The fabrication process consisted of two steps. First, to align and attach a bundle of SWNTs between the source and drain, the alternating (AC) voltage was applied to the electrodes. When a bundle of SWNTs was connected between two electrodes, some of metallic nanotubes and semi-conducing nanotubes existed together. The second step is to burn the metallic SWNTS by applying the voltage between two electrodes. With increasing the voltage, more current flowed through the metallic SWNTs, thus, the metallic SWNTs burnt earlier than the semiconducting one. This technique enables to obtain only semi-conducting SWNTs connection in the transistor. Through the I-V characteristic graph, the moment of metallic SWNTs burning and the characteristic of semi-conducing nanotubes were verified.     

十六烷基三甲基溴化铵修饰的羧基化单壁碳纳米管的细胞毒性

采用十六烷基三甲基溴化铵（CTAB）作为表面活性剂修饰羧基化的单壁碳纳米管（SWNT-COOH/CTAB）,并对原始单壁碳纳米管（SWNTs）与羧基化修饰的单壁碳纳米管（SWNT-COOH）进行材料学特征比较。通过细胞活力和细胞凋亡实验对SWNTs、SWNT-COOH和SWNT-COOH/CTAB的细胞毒性进行比较。结果表明,羧基化修饰的单壁碳纳米管比原始单壁碳纳米管的毒性小,单壁碳纳米管经羧基化后其毒性降低;浓度及时间曲线显示SWNT-COOH/CTAB的毒性与表面活性剂CTAB相关,CTAB和 SWNT-COOH/CTAB的细胞毒性在低浓度范围内（0.5-25μg/mL）是可接受的。十六烷基三甲基溴化铵修饰的羧基化单壁碳纳米管在低浓度范围（0.5-25μg/mL）内可以较安全地用于生物医学领域。     

SWNTs coated by conducting polyaniline: Synthesis and modified properties

Conducting polyaniline (PaN) was synthesized onto single-wall carbon nanotubes (SWNTs) by using the in situ polymerization method. Elemental analysis (EA), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR), field emission scanning electron microscope (FE-SEM), thermal gravimetric analysis (TGA), electron spin resonance (ESR), X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to characterize the resulting complex nanotubes (SWNTs–PaN) structure. We observed no significant interaction chemically between the PaN and SWNTs. The physical properties of the complex nanotubes were measured and also showed that the SWNTs were modified by conducting polyaniline.     

Surface functionalization of single-walled carbon nanombes using metal nanoparticles

Surface functionalization of suspended single-walled carbon nanotubes (SWNTs) using metal (Au) nanoparticles (NPs) is reported. SWNTs are grown on three-dimensionally patterned substrates by thermal chemical vapor deposition and successfully functionalized with Au NPs. Ethylendiamine is mainly used to functionalize SWNTs surface with amino groups before introducing Au NPs. From Raman scattering spectroscopy of the Au-functionalized suspended SWNTs, enhanced Raman scattering properties are obtained. The results suggest that the attached Au NPs may contribute to the enhancement of resonant phenomena. By measuring the electric properties after each functionalization process, it is found that Au NPs act as electron acceptor to the amine functionalized SWNTs.     

Distribution of electric field for carbon nanotube assembly: Experiments (II)

The distribution effect of electric field on the alignment and attachment of carbon nanotubes (CNTs) were investigated. The experimental results were compared with the simulation results according to three different shaped electrodes. In previous simulation, the round shaped electrodes were expected to be more effective for aligning and attaching a single CNT between two electrodes than conical or rectangular shaped electrodes. To verify the simulation results, three different shaped electrodes were introduced and a single multi-walled carbon nanotube (MWNT) was attached. The optimal conditions for aligning and attaching MWNTs such as the frequency, applied voltage and concentration of MWNTs solution were investigated. Through repeated experiments, frequency of 100 kHz-10 MHz, applied voltage of 0.3-1.3 Vrms/μm, concentration of 5 μg/mL in MWNTs solution were obtained as a possible condition range to attach MWNTs. Under these conditions, the yield of MWNTs attachment between two electrodes was up to 70%. In previous simulation, furthermore, it was verified that the size of the stable or quasi-stable region made CNTs aligned and attached on different shaped electrodes from the comparison of the experimental and simulation results. Most single MWNT attachment was accomplished on the round shaped electrodes.     

十六烷基三甲基溴化铵修饰的单壁碳纳米管和寡核苷酸的结合及细胞毒性(英文)

应用十六烷基三甲基溴化铵(CTAB)作为表面活性剂修饰单壁碳纳米管,研究CTAB修饰后的单壁碳纳米管的分散情况和表面电荷情况;观察在场发射扫描电子显微镜和透射电子显微镜下的形貌,同时还研究CTAB修饰后的单壁碳纳米管与小干扰RNA结合的最佳浓度配比,以及CTAB功能修饰后的碳纳米管对培养的人脐静脉内皮细胞的毒性。结果表明:CTAB修饰后的单壁碳纳米管分散良好,CTAB吸附到单根或成束的碳纳米管管壁上,表面带正电荷;与带负电荷的寡核苷酸分子小干扰RNA可以结合,并且CTAB-SWNT与小干扰RNA结合比例达到1:1.5到1:2之间时基本饱和;缺乏CTAB的单壁碳纳米管不能结合小干扰RNA;没有分散的单壁碳纳米管具有更大的细胞毒性,CTAB可以改善SWNTs的分散性,从而减轻单壁碳纳米管的细胞毒性。     

SERS,FT-IR and photoluminescence studies on single-walled carbon nanotubes/conducting polymers composites

Surface-enhanced Raman scattering (SERS), Fourier transform infrared (FT-IR) and photoluminescence (PL) spectroscopies were used to investigate composites based on single-walled carbon nanotubes (SWNTs) and different conducting polymers like polyaniline (PANI), poly-paraphenylene vinylene (PPV) and poly 3-hexylthiophene (3-PHT). In the case of SWNTs/PANI, different composites are obtained by adding dispersed SWNTs powder to the polymer solutions and by chemical polymerization of aniline in presence of SWNTs. The difference originates in the irreversible chemical transformation of SWNTs in the polymerization medium. The synthesis medium used for the preparation of PANI transforms SWNTs in fragments of shorter length like closed-shell fullerenes. This explains the similarity of SERS and FT-IR spectra of the composites PANI/SWNTs and PANI/C₆₀, chemically synthesized. Electrochemical polymerization of aniline in an HCl solution on a SWNT film leads to a covalent functionalization of SWNTs with PANI. In this case, Raman scattering data suggest an additional nanotubes roping with PANI as a binding agent. A post treatment with the NH₄OH solution of polymer-functionalized SWNTs involves an internal redox reaction between PANI and carbon nanotubes. As a result, the polymer chain undergoes a transition from the semi-oxidized state into a reduced one. In the case of PPV and 3-PHT, the effect of the concentration of SWNTs on the photoluminescence properties will be described and compared, as probes of interaction.     

载铂二氧化钛纳米管电极的制备及电催化性能

用水热法在二氧化钛纳米管上负载纳米铂微粒,制备出大比表面积、高表面原子数的载铂二氧化钛纳米管电极。 SEM和XRD分析证明纳米管上已负载20~30 nm的铂微粒。循环伏安测试结果表明：不含染料的体系中,载铂二氧化钛纳米管电极在0.13 V处的氧化峰电流密度为Pt片电极的10倍;含染料的体系中,载铂二氧化钛纳米管电极上对酸性大红GR的氧化峰电流密度达到Pt片电极上的4.2倍。对酸性大红GR的降解实验表明,载铂二氧化钛纳米管电极催化活性高、降解快速高效     

Fabrication of carbon nanotube based transparent conductive thin films using layer-by-layer technology

This paper presents a simple and convenient process for the fabrication of carbon nanotube based optically transparent and electrically conductive thin films. Single-walled carbon nanotubes (SWNTs) are chemically treated to introduce negatively charged carboxylic groups on their surfaces, so that a stable SWNT aqueous dispersion can be obtained without any surfactant. The substrate surface is modified by a layer-by-layer nanoassembly technique, in which a positively charged hydrophilic polymer molecular layer is formed on the top of the substrate. This helps the SWNT dispersion to be cast onto the substrate using convenient wet coating techniques and increases the bonding force between the thin films and the substrates. Using the developed process, large sizes of conductive pure SWNT thin films that are uniform and highly transparent have been fabricated.     

Voltammetric study of fullerene C60 and fullerene C60 nanotubes with sandwich method

Two sandwich-type electrodes (RTIL/C₆₀/SWNT/GCE and RTIL/C₆₀ nanotube/SWNT/GCE) with fullerene C₆₀ or fullerene C₆₀ nanotubes interlayer covered by room temperature ionic liquid (RTIL) membrane on single-walled carbon nanotubes (SWNTs) modified glassy carbon electrode (GCE) surface were fabricated. Cyclic voltammetry and differential pulse voltammetry were used to characterize their electrochemical behaviors and the difference between fullerene C₆₀ and fullerene C₆₀ nanotubes was investigated and the reason was presumed for the first time. It has been observed that 4 pairs of quasi-reversible redox peaks occurred at the RTIL/C₆₀/SWNT/GCE, while only two peaks at the RTIL/C₆₀ nanotube/SWNT/GCE. The cathodic and anodic peak potentials did not shift with the change of pH, indicating that no protons were involved in the electrode reaction processes. So the redox reaction of the fullerene C₆₀ or fullerene C₆₀ nanotubes could be considered as a multi-step one-electron transfer process and fullerene C₆₀ behaved like an electron accumulator to accept and release electrons. While, the reductive products of fullerene C₆₀ nanotubes could not be oxidized again in the reverse scan and the electrode process was irreversible. The fullerene C₆₀ monomer released the accumulated electrons more easily than the fullerene C₆₀ nanotubes. The electrochemical behaviors showed that the electrochemical processes at both electrodes were adsorption-controlled processes.     

球磨法制备碳纳米管/铜复合材料

用球磨法制备了碳纳米管/Cu复合材料粉末,采用扫描电镜（SEM）对不同工艺制备的复合粉末进行研究.结果表明,采用两步实验,通过调节工艺参数,可以得到恰当长度的碳管,能够实现碳管在铜基体中的有效分散.     

Purification and length separation of single-walled carbon nanotubes using chromatographic method

Purification and length separation of oxidatively shortened single-walled carbon nanotubes (SWNTs) were achieved by size exclusion chromatography (SEC) without assistant reagents for dispersion. Almost all the carbonaceous impurities, such as carbonaceous particles, graphene fragments, can be removed from the oxidatively shortened SWNTs materials. The short carbon nanotubes were separated into fractions according to nanotube lengths, and the length distribution of each fraction was relatively narrow.     

电子束辐照对多壁碳纳米管的影响（英文）

在室温下采用透射电子显微镜中汇聚的电子束辐照多壁碳纳米管。结果表明,在能量为100 keV的电子束辐照下除了碳纳米管管壁有一些弯曲外没有其他结构被破坏;当电子能量增加到200 keV时,纳米管有明显的损伤,可以观察到纳米管的无定型化、纳米管外壁的凹坑和缺口。200 keV的电子束辐照还能形成碳洋葱和2根多壁纳米管的焊接。多壁碳纳米管的离位阀能为83~110 keV。能量超过阀能的电子束可以很轻易地损伤纳米管而低于阀能的电子束则很难损坏纳米管,其损伤机理为溅射和原子离位。     

Transformation of singlewalled carbon nanotubes to multiwalled carbon nanotubes and onion-like structures by nitric acid treatment

We have obtained various phases during the refluxing process of singlewalled carbon nanotubes (SWNTs) in 30% HNO₃ acid solution at 100 °C. From the similar treatment in HCl acid solution, we observe no structural phase transformation but enlargement of the bundle size of SWNTs. This strongly suggests that the intercalation of nitric acids into the bundles, which is evidenced by the distribution of smaller diameters of bundles, induces the disintegration of tubes by oxidative etching first and the reformation into multiwalled nanotubes, cone-capped phase, and further onion-like structures. The origin of such a transformation mechanism is further discussed.     

Preparation and properties of Cu matrix composite reinforced by carbon nanotubes

Cu matrix composites reinforced by carbon nanotubes(CNTs) were prepared. The effect of carbon nanotubes on mechanical and tribological properties of the Cu matrix composites were investigated. The chemical method for coating CNTs was reported. The morphology of the fracture surfaces and worn surface were examined by SEM.The results show that Cu/coated-CNTs composites have higher hardness, much better wear resistance and antifriction properties than those of the reference Cu alloy (Cu-10Sn) and Cu/uncoated-CNTs composite sintered under the same conditions. The optimal mechanical properties of the composites occurred at 2. 25%(mass fraction) of CNTs. The excellent wear resistance and anti-friction properties are attributed to the fiber strengthening effect of CNTs and the effect of the spherical wear debris containing carbon nanotubes on the tribo-surface.     

Effect of multi-walled carbon nanotubes on tribological properties of lubricant

After purified by mixture of sulfuric acid and nitric acid, the multi-walled carbon nanotubes(MWNTs) were modified with stearic acid(SA). The modified carbon nanotubes as lubricant additive were utilized to prepare lubricant, and the effects of carbon nanotubes on the tribological properties were investigated by using a pin-on-plate wear tester. The surface structure of MWNTs was examined by transmission electron microscopy, Raman spectroscopy and infrared spectroscopy. The results show that the surfaces of MWNTs are coated with a modified layer of SA. Furthermore, the modified MWNTs as lubricant additive can effectively improve the friction-reduction and antiwear ability of lubricant. The friction coefficient of base lubricant decreases by about 10% and the wear loss of base lubricant decreases by 30%-40% when the concentration of modified MWNTs in lubricant is 0.45 %. In addition,the mass ratio of SA to MWNTs influences the friction-reduction and anti-wear ability of the modified MWNTs as lubricant additive. The optimum mass ratio of MWNTs to stearic acid is about 3 : 8 - 1 : 2.     

Study of interactions in carbon nanotubes systems by using Raman and SERS spectroscopy

We present results obtained on carbon nanotube systems by means of Raman scattering and surface enhanced Raman scattering (SERS). Such systems consist of single-walled nanotubes (SWNTs), multi-walled nanotubes (MWNTs), or polymer/nanotubes composites. In particular, we have focused our studies on the interactions taking place in these compounds which lead to an upshift of the radial breathing mode (RBM) in the case of SWNTs, either when they are arranged in bundles or embedded in polymers. Similar calculations has allowed us to interpret the low frequency Raman modes observed in purified MWNTs. We show that they come from the RBM of individual tubes. From intensity calculations performed to simulate Raman spectra, we demonstrate the importance of two experimental parameters, namely the diameter of internal tubes and the number of shells which constitute the MWNTs, such parameters being extracted experimentally from high resolution transmission electron microscopy images.     

Application of spherical Ni（OH）2/CNTs composite electrode in asymmetric supercapacitor

1 Introduction Electrochemical capacitors (hereafter ECs) have greater power density than usual batteries and can be deeply discharged without any deleterious effect on life time[1]. Activated carbon(AC) with various modifications is the electrode materia…     

Organic light emitting diodes fabricated with single wall carbon nanotubes dispersed in a hole conducting buffer: the role of carbon nanotubes in a hole conducting polymer

In order to investigate the role of single wall carbon nanotubes (SWNTs) in a hole conducting polymer, organic light emitting diodes (OLEDs) were fabricated with a conjugated emissive copolymer, poly(3,6-N-2-ethylhexyl carbazolyl cyanoterephthalidence) (PECCP) and SWNTs dispersed in a hole conducting buffer polymer, polyethylene dioxythiophene (PEDOT). Devices made with SWNTs dispersed in PEDOT and devices made without SWNTs in the PEDOT emit green light at 2.37 eV as expected for PECCP. However, we observed that the device made with SWNTs in the buffer layer shows a significant decrease in the electroluminescence (EL) as compared to that of the device without the SWNTs. In contrast, the photoluminescence (PL) from the same organic layer combination, excited from the PECCP side and measured through the PEDOT and the indium tin oxide glass, shows very little difference between the films with and without the SWNTs. The current–voltage (I–V) characteristics of OLEDs with SWNTs show a lower I–V power dependence (I–V²) near 1–2 V than that of the device without SWNTs which has a power dependence of I–V⁵. The EL and the I–V data together with the PL suggest an electronic interaction between the SWNTs and the host polymeric material, PEDOT. We propose that this electronic interaction originates from the hole trapping nature of SWNTs in a hole conducting polymer.     

碳纳米管改性无机-有机水性富锌涂料的制备及其性能

在常见的水性无机硅酸盐富锌涂料中添加适量的硅丙乳液及碳纳米管,制成了无机-有机复合水性富锌涂料。对几种不同配比涂层的主要力学性能、电化学性能、耐盐雾性能及耐空蚀性能进行了测试分析,结果表明当硅丙乳液和碳纳米管分别占基料的20%和1%,颜基比为2:1时,涂料的基料稳定,喷涂粘度适中;同时涂层在保持了无机富锌涂料优异耐腐蚀性能的基础上,其耐空蚀性能也得到了很大提高。