The growth of aligned carbon nanotubes on quartz substrate by spray pyrolysis of hexane

Vertically aligned multiwall carbon nanotubes were grown by spray pyrolysis of hexane as the carbon source in the presence of ferrocene as catalyst precursor on a quartz substrate. In recent work we used optimal experimental parameters for the feeding method, reactor conditions, reaction temperature and time, concentration of catalyst and flow rate of feed and gas. The process parameters were chosen so as to obtain multiwall carbon nanotubes and aligned multiwall carbon nanotubes. The tubes are around 15-80?nm in diameter. The morphology and structure of the samples were characterized by x-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy analyses.     

Individual multiwall carbon nanotubes spectroscopy by scanning transmission X-ray microscopy

Scanning transmission X-ray microscopy (STXM) has been used to probe the electronic structure of individual multiwall carbon nanotubes by chemical mapping at the nanoscale. Carbon 1s near-edge X-ray absorption fine structure (NEXAFS) spectra of individual structures are shown to be able to differentiate carbon nanotubes from onionlike carbon nanoparticles and to differentiate nanotubes synthesized by different growth methods. Imaging of the very same region by both STXM and transmission electron microscopy is shown to be a very useful and complementary approach.     

Multiwall and bamboo-like carbon nanotube growth by CVD using a semimetal as a catalyst

Multiwall carbon nanotubes have been synthesized on silicon substrates via atmospheric pressure chemical vapour deposition technique using bismuth as a catalyst. Field emission scanning electron microscopy analysis suggests that the samples grow through a tip growth mechanism. High-resolution transmission electron microscopy analysis shows spaghetti-like multiwall carbon nanotubes and with a bamboo-like structure obtained using the Bi catalyst. The quality, in terms of the graphitic crystallinity of the as grown carbon nanotubes, was analyzed by Raman analysis. The study shows that the catalyst, namely bismuth strongly influences the growth density and graphitic crystallinity of the grown carbon nanotubes.     

Cytotoxicity properties of functionalised carbon nanotubes on pathogenic bacteria

Nanobiotechnology is a promising field concerned with the using of engineered nanomaterials, which leads to the improvement of new human remedial against pathogenic bacteria modalities. In this work, silver nanoparticles (AgNPs) were prepared by an easy, cheap and low‐cost electro‐chemical method. The AgNPs were then loaded successfully on to multi‐walled carbon nanotubes (MWCNTs) using a modified chemical reaction process. The AgNPs on the MWCNTs were well spread and evenly distributed on the surfaces of the long nanotubes with well‐graphitised walls as examined by high‐resolution transmission electron microscopy. X‐ray diffraction and transmission electron microscopy were used for sample characterisation. Good dispersion of AgNPs was obtained on the surface of MWCNTs, resulting in an efficient reactivity of the carbon nanotubes surfaces. Finally, the antibacterial activity of AgNPs/MWCNTs hybrid was evaluated against two pathogenic bacteria Pseudomonas aeruginosa and Staphylococcus aureus exhibited excellent activity.Inspec keywords: nanocomposites, X‐ray diffraction, nanofabrication, nanoparticles, transmission electron microscopy, toxicology, silver, antibacterial activity, microorganisms, nanomedicine, multi‐wall carbon nanotubes, electrochemistryOther keywords: engineered nanomaterials, human remedial, pathogenic bacteria modalities, silver nanoparticles, multiwalled carbon nanotubes, modified chemical reaction process, well‐graphitised walls, high‐resolution transmission electron microscopy, cytotoxicity properties, functionalised carbon nanotubes, carbon nanotube surfaces, nanobiotechnology, low‐cost electrochemical method, AgNP‐MWCNT hybrid, X‐ray diffraction, antibacterial activity, Pseudomonas aeruginosa, Staphylococcus aureus, Ag‐C     

Selective Formation of Metal Nanoparticles on the Sidewalls of Carbon Nanotubes

Pt and Au nanoparticles spontaneously form on the sidewalls of single-walled carbon nanotubes (SWNTs) and multiwall carbon nanotubes (MWNTs) in a selective manner. Scanning electron microscope (SEM) and transmission electron microscope (TEM) studies reveal that metal ions are first absorbed on the sidewalls of carbon nanotubes (CNTs) and then are reduced by ethanol. This mechanism is tentatively proposed and discussed.     

A facile and novel way for the synthesis of nearly monodisperse silver nanoparticles

A facile and novel way was reported for the preparation of nearly monodisperse silver nanoparticles with controlled hydrophilic or hydrophobic surface, using trioctylphosphine as the surfactant and stabilizer. The synthesized nanoparticles were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and UV-vis spectroscopy. The monodisperse silver nanoparticles showed a strong surface plasmon resonance band at 402 nm from the UV-vis spectrum.     

Study on novel poly (vinyl pyrrolidone) doped MWCNTs/polyrhodanine nanocomposites: Synthesis,characterization, and thermal performance

In this paper, poly (vinyl pyrrolidone) (PVP) doped multiwall carbon nanotubes (MWCNTs/polyrhodanine), were synthesized through one-step chemical oxidative polymerization of rhodanine monomers on the surface-modified carbon nanotubes. Characterization of MWCNTs/polyrhodanine was conducted by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transforms infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and EDX spectrum analyses in which the results confirmed the successful formation of MWCNTs/polyrhodanine. In addition, to investigate the thermal properties of samples, thermogravimetric analysis (TGA) was employed, and results exhibited significant improvement in the nanocomposite thermal stability due to the addition of MWCNTs with reinforcement effect in polymer matrix.     

Carbon nanotubes and other fullerenes produced from tire powder injected into an electric arc

A novel method of growing multiwall carbon nanotubes by injecting tire powder into an electric arc has been developed. The process is optimized using a DC electric arc in pressurized helium. The multiwall carbon nanotube product and the optimization process are characterized by transmission electron microscopy.     

热等离子射流法CO_2O_3/FeS催化裂解甲烷制备碳纳米管的研究

以CO_2O_3和FeS的混和物做催化剂前驱物,利用热等离子射流法制得包含碳纳米管的固相物,通过扫描电镜、透射电镜对产物进行表征并与高纯单质金属催化碳纳米管生长的类似文献报道做对比,证实其中碳纳米管密度大、纯度高、管径分布小、大部分为50～90nm的直线型多壁管且相互独立、管壁平滑、厚度约为10nm,在数量和质量上均可与已报道文献相比.结果表明,催化剂中微量氧的存在不仅不会影响催化效果,还有助于提高产物中碳纳米管纯度.     

Influence of metal nanoparticle decorated CNTs on polyurethane based electro active shape memory nanocomposite actuators

Polymer nanocomposites based on thermoplastic polyurethane (PU) elastomer and metal nanoparticle (Ag and Cu) decorated multiwall carbon nanotubes (M-CNTs) were prepared through melt mixing process and investigated for its mechanical, dynamic mechanical and electro active shape memory properties. Structural characterization and morphological characterization of the PU nanocomposites were done using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Morphological characterization revealed better dispersion of M-CNTs in the polyurethane, which is attributed to the improved interaction between the M-CNTs and polyurethane. Loading of the metal nanoparticle coated carbon nanotubes resulted in the significant improvement on the mechanical properties such as tensile strength of the PU composites in comparison to the pristine carbon nanotubes (P-CNTs). Dynamic mechanical analysis showed that the glass transition temperature (Tg) of the polyurethane increases slightly with increasing loading of both pristine and metal nanoparticle functionalized carbon nanotubes. The metal nanoparticles decorated carbon nanotubes also showed significant improvement in the thermal and electrical conductivity of the PU/M-CNTs nanocomposites. Shape memory studies of the PU/M-CNTs nanocomposites exhibit remarkable recoverability of its shape at lower applied dc voltages.     

Tuning photoresponse through size control of Cu nanoparticles deposited on multi wall carbon nanotubes

In this paper we illustrate a simple method for the production of multiwall carbon nanotubes thin films decorated with copper metal nanoparticles. The structural information obtained from the transmission electron microscopy study performed on samples differing in the quantity of deposited Copper was linked to the opto-electronic properties evaluated with photo-electrochemical measurements. The photo-response evaluated in terms of incident photon-to-charge carrier generation efficiency varied for different sized-Cu-multiwall carbon nanotubes samples across all the visible and near-ultraviolet photon energy range with respect to the response of bare carbon tubes. The photo-response from the sample covered with of 0.5 nm Cu nominal thickness, reached 10.2%, a value 2 times higher than that measured for bare carbon tubes of 5.9%. While this value decreased to 2.8% when the Cu nominal coverage thickened up to 3 nm. The increase in the photo-response found was interpreted as being the result of a remarkable charge transfer between the Cu metal nanoparticles and the carbon atoms in the tube due to the formation of a strong ionic bond at their interface. The results obtained prove that the metal nanoparticle-carbon nanotube composites have optical, electrical and structural properties that can be applied in a variety of nanoscale architectures for novel photo-electrochemical devices.     

金属钴填充碳纳米管的微结构研究

以Co/硅胶为催化剂,采用化学催化法制备了金属Co填充的碳纳米管,并用高分辨透射电镜(HRTEM),微区电子衍射(SAED)及纳米束能谱分析(EDS)等现代手段对碳纳米管和填充物的形态和微结构进行了深入研究.结果表明,本实验采用的方法能获得大量的被金属Co填充的碳纳米管,填充物为具有面心立方结构的α-Co,填充的α-Co经常出现孪晶.本文还阐明了整个填充的微观过程并对生长机理进行了初步探讨.     

Decoration of single-walled carbon nanotubes with Pt nanoparticles from an organometallic precursor

Carbon nanotubes (CNTs) are nanomaterials of high interest due to their unique structural, electrical, and mechanical properties. Carbon materials have been widely employed to support metallic nanoparticles for catalysis and electrochemical applications. In this work, we investigated the synthesis of platinum nanoparticles generated from the complex Pt₂(dba)₃ (tris(dibenzylideneacetone) diplatinum) and stabilized with a long alkyl chain amine, hexadecylamine (HDA) and supported on functionalized single-walled carbon nanotubes (SWCNTs). High resolution transmission electron microscopy (HRTEM) studies revealed isolated Pt nanoparticles (2?C3 nm) on SWCNTs. Powder X-ray diffraction (XRD) was used to assess the structure of Pt nanoparticles dispersed on SWCNTs assigned to Pt face-centered cubic (fcc). Additionally, infrared Fourier transform spectroscopy confirmed the presence of the stabilizer at the surface of the Pt nanoparticles even after the purification step and functional groups at the surface of pre-treated SWCNTs. This synthetic method may be an alternative route to prepare small size Pt nanoparticles supported on functionalized SWCNTs.     

Deposition of metallic nanoparticles on carbon nanotubes via a fast evaporation process

A new technique was developed for the deposition of colloidal metal nanoparticles on carbon nanotubes. It involves fast evaporation of a suspension containing sonochemically functionalized carbon nanotubes and colloidal nanoparticles. It was demonstrated that metallic nanoparticles with different sizes and concentrations can be deposited on the carbon nanotubes with only a few agglomerates. The technique does not seem to be limited by what the nanoparticles are, and therefore would be applicable to the deposition of other nanoparticles on carbon nanotubes. PtPd and CoPt(3) alloy nanoparticles were used to demonstrate the deposition process. It was found that the surfactants used to disperse the nanoparticles can hinder the nanoparticle deposition. When the nanoparticles were washed with ethanol, they could be well deposited on the carbon nanotubes. The obtained carbon nanotube supported metal nanoparticles were characterized by transmission electron microscopy, energy dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, and cyclic voltammetry.     

Preparation and investigation of multiwall carbon nanotube—polymer composites

In our research we focus on thermoplastic composites of multiwall carbon nanotubes. Different composition of carbon nanotubes and polymers were produced by a special mixing unit called Infinitely Variable Dynamic Shear Mixer (IDMX) using ABS and polycarbonate polymers as matrix materials. Polycarbonate/multiwall carbon nanotube masterbatch was used in the preparation of different compositions. Concentration series were manufactured and investigated. The nanotube composites were granulated and test pieces were injection moulded. The prepared materials were characterised by scanning electron microscopy. Mechanical, electrical properties of the materials were also determined. Correlation was found between the yield stress and the nanotube contents. Impact strength of the composites decreased with the nanotube content, showing more rigid structure than the original pure matrix material. Glass transition of the composites was determined by DSC method. It was found that the characteristic temperatures change by the ratio of the pure materials. Slight change also was found as the carbon nanotube content changes.     

Preparation of gold/polyaniline/multiwall carbon nanotube nanocomposites and application in ammonia gas detection

Composites of multiwall carbon nanotubes (MWNTs), polyaniline (PANI), and gold nanoparticles were prepared by one pot synthesis. Based on the interaction between aniline monomers and MWNTs, aniline molecules were adsorbed and polymerized on the surface of MWNTs. The nanocomposites were characterized by transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoemission spectroscopy (XPS). The sensors based on Au/PANI/MWNT nanocomposites were tested for on-line monitoring of ammonia gas. The results show that the as-prepared sensors have superior sensitivity, and good repeatability upon repeated exposure to ammonia gas.     

Synthesis of Hybrid Materials Based on Iron Nanoparticle-Decorated Multiwalled Carbon Nanotubes

Fe-containing nanoparticles have been grown for the first time on the surface of multiwalled carbon nanotubes by metalorganic chemical vapor deposition using iron acetylacetonate, Fe(acac)₃, as a precursor. The resultant hybrid nanomaterial has been characterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and thermogravimetric analysis. The results demonstrate that the synthesized material consists of multiwalled carbon nanotubes whose surface is decorated with iron nanoparticles.     

Growth morphology and spectroscopy of multiwall carbon nanotubes synthesized by pyrolysis of iron phthalocyanine

Carbon nanotubes (CNTs) were synthesized by Chemical Vapor Deposition (CVD) from the pyrolytic decomposition of Iron Phthalocyanine (FePc) molecules, on SiO2/Si(111) substrates in the presence of a hydrogen flow. FePc molecules contribute simultaneously both to the formation of the precursor Fe nanoparticles and also as a Carbon source. Different experimental conditions were examined. Samples were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and inverse photoemission. The resulting samples are highly oriented multiwall carbon nanotubes films, with heights in the range between: 4 and 20 microm. The tubes diameter is strongly dependent on growth temperature. Our experimental results show evidence of a transition in the growth mechanism, from a tip growth to a base growth mode, as the decomposition temperature is increased. Preliminary spectroscopic measurements performed on these MWCNTs, show the unoccupied density of states has several resonances close to Fermi level, related both to the graphene electronic structure and the formation of the tube.     

Electrical and optical characteristics of surface treated ZnO nanotubes

Vertical ZnO nanotubes were electrochemically deposited onto an indium doped tin oxide glass substrate. These nanotubes were surface treated with zinc acetate and annealed at 450 °C, resulting in a nanotubes/nanoparticles composite layer. Scanning electron microscopy of the surface treated samples showed nanoparticles been dispersed uniformly along the ZnO tubular matrix, which was confirmed by X-ray diffractrometry. Photoluminescence and fluorescence microscopy showed untreated ZnO nanotubes exhibiting blue emission, while the treated samples exhibited green emissions. Ultra-violet spectroscopy of treated samples revealed lower band gap values compare to their untreated counterparts. Lifetime measurements showed higher excitonic lifetimes in treated samples. Conductance studies using atomic force microscopy showed significant improvement in the conductance values for the treated samples. A significant increase in photocurrent was observed in treated samples when used as photo-anodes in dye sensitized solar cells.     

Electrorheological properties of poly(acrylonitrile) microspheres coated with multiwall carbon nanotubes

Poly(acrylonitrile) (PAN) particles coated with functionalized multiwall carbon nanotubes (fMCNTs) were prepared and applied to electrorheological (ER) fluids. First, carboxylic acid groups were introduced on the multiwall carbon nanotubes by chemical oxidation method. Then, nitrile groups on the surface PAN particles were modified to amine groups by Co catalysis reaction. Finally, fMCNTs were anchored on the surface of polymer particles by covalent bonding between carboxylic acid groups on fMCNTs and amine groups on particles. fMCNTs attached polymeric microspheres were characterized by scanning electron microscopy and optical microscopy. The ER properties of fMCNTs modified microspheres were measured under controlled electric fields. Although the amount of fMCNTs anchored on the surfaces of microspheres was 1 wt.% of polymers, good ER properties were observed. This improvement may be caused by fMCNTs enhancing the electrical properties of polymer microspheres.