Direct Vapor-Phase Bromination of Multiwall Carbon Nanotubes

We present the simple procedure of the vapor-phase bromination of multiwall carbon nanotubes (MWNTs) at moderate temperatures. MWNTs with average diameter9±3 nm were treated with Br2vapors at 250°C to produce Br-functionalized product. Transmission electron microscopy analysis was used to prove low damage of MWNT walls during bromination. X-ray photoelectron spectroscopy (XPS) and differential thermal analysis (DTA) were used to investigate chemical composition of the surface of initial and brominated nanotubes. The experimental results show that the structure of MWNTs is not affected by the bromination process and the total amount of Br-containing surface functions reaches 2.5 wt. %. Electrophysical properties of initial and brominated MWNTs were investigated showing decrease of conductivity for functionalized sample. Possible mechanism of the vapor-phase bromination via surface defects and oxygen-containing functional groups was proposed according to data obtained. Additional experiments with bromination of annealed low-defected MWNTs were performed giving Br content a low as 0.75 wt. % proving this hypothesis.

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CHARACTERIZATION AND ELECTRICAL PROPERTIES OF ALIGNED CARBON NANOTUBES WITH HIGH ASPECT RATIO

International Journal of Nanoscience ◽

10.1142/s0219581x11007545 ◽

2011 ◽

Vol 10 (01n02) ◽

pp. 23-28

Author(s):

RAVI BHATIA ◽

V. PRASAD ◽

M. REGHU

Keyword(s):

Electron Microscopy ◽

Carbon Nanotubes ◽

Aspect Ratio ◽

Multiwall Carbon Nanotubes ◽

High Quality ◽

Transmission Electron Microscopy Analysis ◽

Transmission Electron ◽

Electron Microscopy Analysis ◽

High Degree

High-quality multiwall carbon nanotubes (MWNTs) were produced by a simple one-step technique. The production of MWNTs was based on thermal decomposition of the mixture of a liquid phase organic compound and ferrocene. High degree of alignment was noticed by scanning electron microscopy. The aspect ratio of as-synthesized MWNTs was quite high (more than 4500). Transmission electron microscopy analysis showed the presence of the catalytic iron nanorods at various lengths of MWNTs. Raman spectroscopy was used to know the quality of MWNTs. The ratio of intensity of the G-peak to the D-peak was very high which revealed high quality of MWNTs. Magnetotransport studies were carried out at low temperature and a negative MR was noticed.

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Effect of Surface Modification of Multiwall Carbon Nanotubes on their Electrical and Surface Properties

Materials Science Forum ◽

10.4028/www.scientific.net/msf.636-637.676 ◽

2010 ◽

Vol 636-637 ◽

pp. 676-681 ◽

Cited By ~ 3

Author(s):

M. Omastová ◽

M. Mičušík ◽

Pavol Fedorko ◽

M.M. Chehimi ◽

J. Pionteck

Keyword(s):

Carbon Nanotubes ◽

Surface Properties ◽

Photoelectron Spectroscopy ◽

Cetyltrimethylammonium Bromide ◽

Multiwall Carbon Nanotubes ◽

Dodecylbenzenesulfonic Acid ◽

Molar Ratios ◽

Electrical Conductivities ◽

Multiwall Carbon ◽

Effect Of Surface

The surface of multiwall carbon nanotubes (CNT) was modified by non-covalent approach. Various types of surfactants, an anionic surfactant - dodecylbenzenesulfonic acid, an cationic surfactant - cetyltrimethylammonium bromide and their combination with different molar ratios were used for modification. Different power of ultrasound, 64 or 400 W was used to evaluate its influence on the properties of prepared composites. The electrical conductivities of unmodified CNT, particles treated by ultrasound, and CNT modified with surfactants were measured. The surface properties of modified particles were determined by X-ray photoelectron spectroscopy and scanning electron microscopy. Thermogravimetric analysis was used to confirm the presence and to evaluate the quantity of surfactants in the modified CNT.

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Effect of Carboxylic Functional Group Functionalized on Carbon Nanotubes Surface on the Removal of Lead from Water

Bioinorganic Chemistry and Applications ◽

10.1155/2010/603978 ◽

2010 ◽

Vol 2010 ◽

pp. 1-9 ◽

Cited By ~ 115

Author(s):

Muataz Ali Atieh ◽

Omer Yehya Bakather ◽

Bassam Al-Tawbini ◽

Alaadin A. Bukhari ◽

Faraj Ahmad Abuilaiwi ◽

...

Keyword(s):

Electron Microscopy ◽

Carbon Nanotubes ◽

Functional Group ◽

Multiwall Carbon Nanotubes ◽

Chemical Properties ◽

Average Diameter ◽

Transmission Electron ◽

Physical And Chemical ◽

Multiwall Carbon ◽

Carboxylic Functional Group

The adsorption mechanism of the removal of lead from water by using carboxylic functional group (COOH) functionalized on the surface of carbon nanotubes was investigated. Four independent variables including pH, CNTs dosage, contact time, and agitation speed were carried out to determine the influence of these parameters on the adsorption capacity of the lead from water. The morphology of the synthesized multiwall carbon nanotubes (MWCNTs) was characterized by using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) in order to measure the diameter and the length of the CNTs. The diameters of the carbon nanotubes were varied from 20 to 40 nm with average diameter at 24 nm and 10 micrometer in length. Results of the study showed that 100% of lead was removed by using COOH-MCNTs at pH 7, 150 rpm, and 2 hours. These high removal efficiencies were likely attributed to the strong affinity of lead to the physical and chemical properties of the CNTs. The adsorption isotherms plots were well fitted with experimental data.

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An Easy Methodology for the Incorporation of Carbon Nanotubes on Surfaces of Components Applied as Electronic Devices

Journal of Nano Research ◽

10.4028/www.scientific.net/jnanor.18-19.157 ◽

2012 ◽

Vol 18-19 ◽

pp. 157-163

Author(s):

M. Pérez-Cadenas ◽

A. Maroto-Valiente ◽

I. Rodríguez-Ramos ◽

A. Guerrero-Ruíz

Keyword(s):

Carbon Nanotubes ◽

Photoelectron Spectroscopy ◽

Iron Catalyst ◽

Substrate Surface ◽

Electronic Devices ◽

Chemical Vapour ◽

Multiwall Carbon Nanotubes ◽

Transmission Electron ◽

Vertically Aligned ◽

Multiwall Carbon

Carbon nanotubes are grown by catalytic chemical vapour deposition over components of electronic devices. Samples are analyzed by thermogravimetry, scanning and transmission electron microscopy and X-ray photoelectron spectroscopy. The carbon materials deposited on the microchips present the morphology of multiwall carbon nanotubes and grow vertically aligned on the substrates. The preparation procedure parameters are changed to control sizes and height of the grown multiwall carbon nanotubes. The selectivity to incorporate, or not, carbon nanotubes depends on the chemical composition of the substrate. While carbon nanotubes are efficiently grown on Au surfaces, this reaction does not occur on Pt surfaces. These results correlate with a heterogeneous nucleation of iron catalyst particles on the substrate surface. The resulting composite materials can find numerous technological applications.

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X-Ray Photoelectron Spectroscopy of Anatase-TiO2 Coated Carbon Nanotubes

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.162.163 ◽

2010 ◽

Vol 162 ◽

pp. 163-177 ◽

Cited By ~ 30

Author(s):

Pyrgiotakis Georgios ◽

Sigmund M. Wolfgang

Keyword(s):

Carbon Nanotubes ◽

Photoelectron Spectroscopy ◽

High Efficiency ◽

Arc Discharge ◽

Multiwall Carbon Nanotubes ◽

Thick Layer ◽

Xps Spectra ◽

X Ray ◽

Anatase Titania ◽

Multiwall Carbon

A high efficiency nanocomposite photocatalyst is reported. Multiwall carbon nanotubes (MWNTs) were coated with titania. Two distinct types of nanocomposites were synthesized with variation in the synthetic procedure. One of the nanocomposites is based on a core of arc-discharge synthesized multiwall carbon nanotubes; whereas the other is based on a core of chemical vapor deposition (CVD) grown MWNTs. The nanocomposites have a similar appearance in transmission electron microscopy pictures in that they have a core of MWNTs that are chemically bonded to a few nanometer thick layer of pure anatase phase of titania. Yet they show a dramatically different photocatalytic behavior when they are compared on the basis of rates of photocatalytic decomposition of an organic dye in aqueous media following the Langmuir-Hinshelwood mechanism. This article focuses on the analysis of the differences in the nanocomposites using X-Ray Photoelectron Spectroscopy (XPS). XPS spectra of these materials indicate that there are distinct differences. However, they also show that both share C-O-Ti bonds that transform the carbon in the carbon nanotubes into a dopant for the anatase titania. This doping seems to be essential for long wavelength, i.e. visible light induced photocatalysis.

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Comparison of Electronic Structure and Magnetic Properties of Few Layer Graphene and Multiwall Carbon Nanotubes

Advances in Materials Science and Engineering ◽

10.1155/2016/7362131 ◽

2016 ◽

Vol 2016 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Sekhar Chandra Ray

Keyword(s):

Carbon Nanotubes ◽

Raman Spectroscopy ◽

Photoelectron Spectroscopy ◽

Multiwall Carbon Nanotubes ◽

Hysteresis Loops ◽

Structural Defects ◽

X Ray ◽

Layer Graphene ◽

Few Layer Graphene ◽

Multiwall Carbon

A comparative study has been made for the non-catalyst based few layer graphene (FLG) and Fe-catalyst based multiwall carbon nanotubes (MWCNTs). Magnetic and electronic properties of FLG and MWCNTs were studied using magnetic M-H hysteresis loops and synchrotron radiation based X-ray absorption fine structure spectroscopy measurements. Structural defects and electronic and bonding properties of FLG/MWCNTs have been studied using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and ultraviolet photoelectron spectroscopy (UPS). The work functions of FLG and MWCNTs are 4.01 eV and 3.79 eV, respectively, obtained from UPS (He-I) spectra. UPS (He-II) results suggest that the density of states (DOS) of MWCNTs is higher than FLG and is consistent with Raman spectroscopy result that shows the defect of MWCNTs is higher than FLG. The magnetic coercivity (Hc) of the MWCNTs (~750 Oe) is higher than FLG (~85 Oe) which could be used for various technological magnetic applications.

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SYNTHESIS OF MONODISPERSE Mn3O4 NANOCRYSTALS

International Journal of Nanoscience ◽

10.1142/s0219581x09006213 ◽

2009 ◽

Vol 08 (03) ◽

pp. 281-283 ◽

Cited By ~ 2

Author(s):

MASOUD SALAVATI-NIASARI ◽

FATEMEH DAVAR

Keyword(s):

Photoelectron Spectroscopy ◽

Average Diameter ◽

Binding Energies ◽

X Ray Diffraction ◽

Transmission Electron Microscopy Analysis ◽

X Ray ◽

Transmission Electron ◽

Electron Microscopy Analysis ◽

Microscopy Analysis ◽

20 Nm

Mn3O4 nanocrystals have been prepared using [bis(2-hydroxyacetophenato)manganese(II)] as precursor. Transmission electron microscopy analysis demonstrated nanocrystals Mn3O4 with an average diameter of about 20 nm. The structural study by X-ray diffraction indicates that these nanocrystals have pure tetragonal phase. The phase pure samples were characterized using X-ray Photoelectron Spectroscopy for Mn 2p level. The values of binding energies are consistent with the relative values reported in the literature.

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Boehmite Nanofibers as a Dispersant for Nanotubes in an Aqueous Sol

10.26434/chemrxiv.6652955.v1 ◽

2018 ◽

Author(s):

Gen Hayase

Keyword(s):

Carbon Nanotubes ◽

Aspect Ratio ◽

Aqueous Solutions ◽

High Aspect Ratio ◽

Multiwall Carbon Nanotubes ◽

Multiwall Carbon ◽

Nanotube Films

By exploiting the dispersibility and rigidity of boehmite nanofibers (BNFs) with a high aspect ratio of 4 nm in diameter and several micrometers in length, multiwall-carbon nanotubes (MWCNTs) were successfully dispersed in aqueous solutions. In these sols, the MWCNTs were dispersed at a ratio of about 5–8% relative to BNFs. Self-standing BNF–nanotube films were also obtained by filtering these dispersions and showing their functionality. These films can be expected to be applied to sensing materials.

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