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

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
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.

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

2010 ◽  
Vol 162 ◽  
pp. 163-177 ◽  
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.

Nanobubbles stability and multiwall carbon nanotubes straightening on few-layer graphene surfaces

2011 ◽  
Vol 110 (4) ◽  
pp. 044319 ◽  
Author(s):  
S. H. Al-Harthi ◽  
M. Al-Barwani ◽  
M. Elzain ◽  
N. Al-Naamani ◽  
T. Hysen
Keyword(s):  
Carbon Nanotubes ◽  
Multiwall Carbon Nanotubes ◽  
Layer Graphene ◽  
Few Layer Graphene ◽  
Multiwall Carbon

scholarly journals Increased Electrical Conductivity of Carbon Nanotube Fibers by Thermal and Voltage Annealing

2021 ◽  
Vol 8 (1) ◽  
pp. 1
Author(s):  
Varun Shenoy Gangoli ◽  
Chris J. Barnett ◽  
James D. McGettrick ◽  
Alvin Orbaek White ◽  
Andrew R. Barron
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Raman Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Separate Analysis ◽  
Sweet Spot ◽  
Electrical Conductor ◽  
X Ray ◽  
Resonant Raman ◽  
Carbon Nanotube Fibers

We report the effect of annealing, both electrical and by applied voltage, on the electrical conductivity of fibers spun from carbon nanotubes (CNTs). Commercial CNT fibers were used as part of a larger goal to better understand the factors that go into making a better electrical conductor from CNT fibers. A study of thermal annealing in a vacuum up to 800 °C was performed on smaller fiber sections along with a separate analysis of voltage annealing up to 7 VDC; both exhibited a sweet spot in the process as determined by a combination of a two-point probe measurement with a nanoprobe, resonant Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Scaled-up tests were then performed in order to translate these results into bulk samples inside a tube furnace, with similar results that indicate the potential for an optimized method of achieving a better conductor sample made from CNT fibers. The results also help to determine the surface effects that need to be overcome in order to achieve this.

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

2010 ◽  
Vol 636-637 ◽  
pp. 676-681 ◽  
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.

Stacking Faults in SiC Nanowires

2008 ◽  
Vol 8 (7) ◽  
pp. 3504-3510 ◽  
Author(s):  
K. L. Wallis ◽  
M. Wieligor ◽  
T. W. Zerda ◽  
S. Stelmakh ◽  
S. Gierlotka ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Stacking Faults ◽  
Multiwall Carbon Nanotubes ◽  
Structural Defects ◽  
X Ray Diffraction ◽  
Ir Spectrometry ◽  
X Ray ◽  
Sic Nanowires ◽  
Transmission Electron ◽  
Multiwall Carbon

SiC nanowires were obtained by a reaction between vapor silicon and multiwall carbon nanotubes, CNT, in vacuum at 1200 °C. Raman and IR spectrometry, X-ray diffraction and high resolution transmission electron microscopy, HRTEM, were used to characterize properties of SiC nanowires. Morphology and chemical composition of the nanowires was similar for all samples, but concentration of structural defects varied and depended on the origin of CNT. Stacking faults were characterized by HRTEM and Raman spectroscopy, and both techniques provided complementary results. Raman microscopy allowed studying structural defects inside individual nanowires. A thin layer of amorphous silicon carbide was detected on the surface of nanowires.

Structural Defects Play a Major Role in the Acute Lung Toxicity of Multiwall Carbon Nanotubes: Physicochemical Aspects

2008 ◽  
Vol 21 (9) ◽  
pp. 1690-1697 ◽  
Author(s):  
Ivana Fenoglio ◽  
Giovanna Greco ◽  
Maura Tomatis ◽  
Julie Muller ◽  
Encarnacion Raymundo-Piñero ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Multiwall Carbon Nanotubes ◽  
Lung Toxicity ◽  
Structural Defects ◽  
Multiwall Carbon

scholarly journals Direct Vapor-Phase Bromination of Multiwall Carbon Nanotubes

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Ilya Mazov ◽  
Dmitry Krasnikov ◽  
Andrey Stadnichenko ◽  
Vladimir Kuznetsov ◽  
Anatoly Romanenko ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Vapor Phase ◽  
Photoelectron Spectroscopy ◽  
Surface Defects ◽  
Simple Procedure ◽  
Multiwall Carbon Nanotubes ◽  
Average Diameter ◽  
Transmission Electron Microscopy Analysis ◽  
Electron Microscopy Analysis ◽  
Multiwall Carbon

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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