scholarly journals The Reduction Temperature Effect of Fe–Co/MgO Catalyst on Characteristics of Multi-Walled Carbon Nanotubes

Catalysts ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 361 ◽  
Author(s):  
Paul Kim ◽  
Cheol Lee
Keyword(s):  
Carbon Nanotubes ◽  
Sol Gel ◽  
Chemical Vapor ◽  
Diameter Distribution ◽  
Metal Catalyst ◽  
Reduction Temperature ◽  
Raman Analysis ◽  
Transmission Electron ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Diameters and crystallinity of multi-walled carbon nanotubes (MWCNTs) dependent on reduction temperature of the Fe–Co/MgO catalyst were investigated. MWCNTs were synthesized by catalytic chemical vapor depositing and the Fe–Co/MgO catalyst was fabricated by using a sol-gel method. According to Raman analysis, transmission electron microscopy and thermogravimetric analysis, the diameter distribution of MWCNTs was broadened with increasing reduction temperature of the Fe–Co/MgO catalyst and crystallinity was improved. The above results are attributed to an increased size and enhanced crystallinity of metal catalyst particles by increasing reduction temperature.

scholarly journals Biocompatibility Characteristics of Titanium Coated with Multi Walled Carbon Nanotubes—Hydroxyapatite Nanocomposites

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 224 ◽  
Author(s):  
Jung-Eun Park ◽  
Yong-Seok Jang ◽  
Tae-Sung Bae ◽  
Min-Ho Lee
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Sol Gel ◽  
Pure Titanium ◽  
Cell Proliferation And Differentiation ◽  
Transmission Electron ◽  
Proliferation And Differentiation ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Multi walled carbon nanotubes-hydroxyapatite (MWCNTs-HA) with various contents of MWCNTs was synthesized using the sol-gel method. MWCNTs-HA composites were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). HA particles were generated on the surface of MWCNT. Produced MWCNTs-HA nanocomposites were coated on pure titanium (PT). Characteristic of the titanium coated MWCNTs-HA was evaluated by field-emission scanning electron microscopy (FE-SEM) and XRD. The results show that the titanium surface was covered with MWCNTs-HA nanoparticles and MWCNTs help form the crystalized hydroxyapatite. Furthermore, the MWCNTs-HA coated titanium was investigated for in vitro cellular responses. Cell proliferation and differentiation were improved on the surface of MWCNT-HA coated titanium.

Stacking Nature of the Catalytic Chemical Vapor Deposition-Derived Double-Walled Carbon Nanotubes

2006 ◽  
Vol 6 (11) ◽  
pp. 3321-3324 ◽  
Author(s):  
Yoong-Ahm Kim ◽  
Hiroyuki Muramatsu ◽  
Masahito Kojima ◽  
Takuya Hayashi ◽  
Yutaka Kaburagi ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Chemical Vapor Deposition Method ◽  
Catalytic Chemical Vapor Deposition ◽  
Transmission Electron ◽  
Multi Walled Carbon Nanotubes ◽  
Double Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Here we described the synthesis of highly pure double walled carbon nanotube (DWNT) through a right combination of a catalytic chemical vapor deposition method and the two-step purification and evaluated their stacking infidelity when compared to multi-walled carbon nanotubes (MWNTs). Easy fabrication of thin and flexible, but mechanically tough DWNT-buckypaper was due to the long and large-sized bundled DWNT (up to 50 nm), where DWNTs with diameter below 2 nm were packed in hexagonal array. Through detailed transmission electron microscope, X-ray and Raman studies, we confirmed that the intershell spacing of our DWNT sample was ca. 0.36 nm, which was believed to strongly affect negative and small magnetoresistance absolute value of −0.09 at 77 K and 1 T.

The Role of Metal Catalyst in Near Ambient Hydrogen Adsorption on Multi-walled Carbon Nanotubes

2004 ◽  
Vol 837 ◽  
Author(s):  
Yong-Won Lee ◽  
Rohit Deshpande ◽  
Anne C. Dillon ◽  
Michael J. Hebe ◽  
Hongjie Dai ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Hydrogen Adsorption ◽  
Chemical Vapor ◽  
Metal Catalyst ◽  
Ambient Conditions ◽  
Multiwalled Carbon ◽  
Multi Walled Carbon Nanotubes ◽  
Methane Source ◽  
Temperature Programmed ◽  
Walled Carbon Nanotubes

ABSTRACTMultiwalled carbon nanotubes (MWNTs) were continuously synthesized by hot wire chemical vapor deposition (HWCVD) using a methane source catalyzed by metal-organic ferrocene. The microstructure of the MWNTs and the catalyst particles were subsequently characterized with transmission electron microscopy which identified three different phases, i.e., bcc α-Fe, fcc γ-Fe and orthorhombic Fe3C. The hydrogen storage capacity of MWNTs was determined with temperature-programmed desorption (TPD) technique. Hydrogen adsorption at near ambient conditions was observed only in as-synthesized MWNTs containing iron particles and was dramatically increased after hydrogen reducing treatment. Possible adsorption mechanism was also discussed.

Investigation about Synthesis of Carbon Nanotubes with Various Structures Governed by Temperature and Relevant Growth Mechanism

2012 ◽  
Vol 499 ◽  
pp. 35-39
Author(s):  
Hai Peng Li ◽  
Jia Wei Fan ◽  
Hong Shui Wang ◽  
Li Hui Wang
Keyword(s):  
Carbon Nanotubes ◽  
Growth Mechanism ◽  
Chemical Vapor ◽  
Composite Powders ◽  
Catalyst Carrier ◽  
Transmission Electron ◽  
Multi Walled Carbon Nanotubes ◽  
Synthesis Of Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Multi-walled carbon nanotubes (CNTs)/Al in-situ composite powders over Al as catalyst carrier had been synthesized successfully using transition metal Ni by chemical vapor deposition. CNTs were mainly characterized by transmission electron microscopy. It was found that reaction temperature had great influences on the structures of carbon products obtained. Detailed discussions according to the structures of CNTs at different reaction temperatures were given. A deduced model for explaining the growth mechanism of CNTs governed by temperature was developed.

Rapid Structural Improvement of CVD-Grown Multi-Walled Carbon Nanotubes by Drastic Thermite Reaction

NANO ◽  
2015 ◽  
Vol 10 (08) ◽  
pp. 1550112
Author(s):  
Jiang Zhao ◽  
Jing Chen ◽  
Pengcheng Zhang ◽  
Haofeng Yu ◽  
Jie Chen
Keyword(s):  
Carbon Nanotubes ◽  
Electron Microscope ◽  
Electric Fields ◽  
Chemical Vapor ◽  
Reaction Process ◽  
Thermite Reaction ◽  
Structural Improvement ◽  
Transmission Electron ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Multi-walled carbon nanotubes (MWCNTs) produced by chemical vapor deposition (CVD) are the most common commercial products at extremely low price in the market. However, due to the inherent drawbacks of CVD surroundings at temperature below [Formula: see text][Formula: see text]1000[Formula: see text]C, CVD-grown nanotubes usually have very disordered structure, resulting in most of their properties being much below expectations. Herein, we present a simple and energy-efficient method for improving rapidly the structure of CVD-grown MWCNTs via a drastic thermite reaction process. Direct observations from scan electron microscope (SEM) and transmission electron microscope (TEM) images, decrease of [Formula: see text] ratios in Raman spectra, increase of the starting oxidation temperatures observed in thermogravimetric analysis (TGA), decrease of the volumetric electrical resistivity and decrease of the turn-on electric fields from 3.64 to 2.88[Formula: see text]V/[Formula: see text]m in field emission measurements suggest that the graphitization of MWCNTs can be effectively enhanced and the structure of nanotubes becomes more ordered after the drastic thermite reaction process.

Removal of Metal Catalyst in Multi-Walled Carbon Nanotubes with Combination of Air and Hydrogen Annealing Followed by Acid Treatment

2008 ◽  
Vol 8 (11) ◽  
pp. 5807-5812
Author(s):  
Quanlong Li ◽  
Dongxing Yuan ◽  
Bin Guan ◽  
Qingmei Lin ◽  
Xuefeng Wang
Keyword(s):  
Carbon Nanotubes ◽  
Acid Treatment ◽  
Absorption Spectrometry ◽  
Acid Reflux ◽  
Metal Catalyst ◽  
Hydrogen Annealing ◽  
Flame Atomic Absorption ◽  
Transmission Electron ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Multi-walled carbon nanotubes (MWCNTs) prepared by the decomposition of CH4 on a Ni-MgO catalyst were treated with air and hydrogen annealing, and the combination of air and hydrogen annealing, respectively, followed by acid reflux. The treated MWCNTs were characterized by the techniques of transmission electron microscopy, thermogravimetric analysis and flame atomic absorption spectrometry. The results showed that hydrogen annealed MWCNTs were more air stable than air annealed ones. Followed by acid treatment, the combination of air and hydrogen annealing was more efficient than either air annealing or hydrogen annealing for the removal of catalyst in MWCNTs. For the treatment with 2 h of hydrogen annealing followed by 2 h of air annealing, the catalyst Ni remained in the purified sample was 10.8 μg/g, and the yield rate was 82.3%. With 2 h of air annealing followed by 2 h of hydrogen annealing, the data were 5.8 μg/g and 61.9%, respectively. The different functions of air and hydrogen during annealing were discussed.

Multi-Walled Carbon Nanotubes by Thermal-CVD Utilizing Palm DHSA as a Precursor

2013 ◽  
Vol 667 ◽  
pp. 349-353
Author(s):  
N.F.A. Zainal ◽  
T.I. Tunku Kudin ◽  
A.A. Azira ◽  
A. Zain Ahmed ◽  
Saifollah Abdullah ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Vapor Deposition ◽  
Sol Gel ◽  
Chemical Vapor ◽  
High Yield ◽  
Multi Wall Carbon Nanotubes ◽  
Thermal Chemical Vapor Deposition ◽  
Multi Walled Carbon Nanotubes ◽  
Spectroscopy Studies ◽  
Walled Carbon Nanotubes

We illustrated the optimization of the growth of multi-wall carbon nanotubes (MWCNTs) using thermal chemical vapor deposition (CVD). Palm-based dihydrostearic acid (DHSA) which was never been reported as a precursor, was used as the precursor over five different trimetallic catalysts for the growth of MWCNTs. These trimetallic catalysts were prepared by sol-gel method and used to study on the effect of the production of the MWCNTs from palm DHSA. With different catalyst, the characteristics of MWCNTs changes such as diameter and crystallinity which was confirmed by SEM and Raman spectroscopy studies. The trimetallic catalysts give high yield and offer good graphitization of MWCNTs produced from palm DHSA.

Orientational Growth of Carbon Nanotube by Thermal CVD

2001 ◽  
Vol 706 ◽  
Author(s):  
Shen Zhu ◽  
Ching-Hua Su ◽  
J. C. Cochrane ◽  
S. Gorti ◽  
S. Lehoczky ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Vapor Deposition ◽  
Substrate Surface ◽  
Small Diameter ◽  
Chemical Vapor ◽  
Diameter Distribution ◽  
Thermal Chemical Vapor Deposition ◽  
Multi Walled Carbon Nanotubes ◽  
Temperature And Pressure ◽  
Walled Carbon Nanotubes

AbstractCarbon nanotubes are synthesized using thermal chemical vapor deposition. Various temperature and pressure are used to fabricate carbon nanotubes. It is found that the nanotube-diameter distribution mainly depends on the growth-temperature. With the substrate surface normal either along or against the gravity vector, different growth orientations of multi-walled carbon nanotubes are observed by scanning electron microscopy although the Raman spectra are similar for samples synthesized at different locations. The sizes of these carbon nanotubes in each sample are quite uniform and the length of the tube is up to hundreds of micrometers. These results suggest the gravitation effects in the growth of long and small diameter CNT.

Synthesis and Characteristics of Multi-Walled Carbon Nanotubes-Polyimide Nanocomposite Films

2008 ◽  
Vol 8 (5) ◽  
pp. 2671-2675 ◽  
Author(s):  
Mei-Hui Tsai ◽  
Dong-Sen Chen ◽  
Pei-Chun Chiang ◽  
Hsin-Chuan Lin ◽  
Jih-Mirn Jehng
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Nanocomposite Film ◽  
Chemical Vapor ◽  
Mechanical Analysis ◽  
Nanocomposite Films ◽  
Transmission Electron ◽  
Multi Walled Carbon Nanotubes ◽  
Polyimide Nanocomposite ◽  
Walled Carbon Nanotubes

The polyimide/multi-walled carbon nanotubes (PI/MWNTs) nanocomposite film has been successfully synthesized in this study. The source of MWNTs is prepared by chemical vapor deposition (CVD) method. Then the MWNTs are washed with acid for purification before being added into the polymer matrix. The acid-modified procedure aids in dispersing MWNTs in N,N-dimethylacetamide (DMAc) solvent. Based on the results of field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), the MWNTs are embedded in PI and well-dispersed within the PI matrix. The dynamic mechanical analysis (DMA) shows that the storage modulus of nanocomposite film is increased by 68% with the addition of 1 wt% MWNTs into PI. The nanocomposite films start to decompose at or above 400 °C and lose 5% of its weight at 545 °C according to thermogravimetric analysis (TGA). Meanwhile, the electrical conductivity of the nanocomposite film with 3 wt% MWNTs, is raised more than 10 orders of magnitude from 10−15 to 10−5 S/cm.

scholarly journals Microscopy Studies of Carbon Nanotubes/Ferroelectric Composites for Microelectronics

2012 ◽  
Vol 18 (S5) ◽  
pp. 107-108
Author(s):  
Amit Mahajan ◽  
Rubaiyet Iftekharul Haque ◽  
Paula M. Vilarinho ◽  
Angus Kingon
Keyword(s):  
Carbon Nanotubes ◽  
Field Effect Transistors ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Solution Deposition ◽  
Nano Structures ◽  
Transmission Electron ◽  
Multi Walled Carbon Nanotubes ◽  
Scaling Down ◽  
Walled Carbon Nanotubes

Top-down approaches for continuous scaling-down of devices and components in semiconductor industries is getting increasingly difficult and expensive, and thus bottom–up strategies, e.g., growth of functional nano-structures using nanowires or nanotubes are being explored rather than patterning and etching. Carbon nanotubes (CNTs) are an interesting option under consideration due to their extraordinary physical and electrical properties that make them suitable for microelectronic applications, such as, semiconductor field-effect-transistors (FET) and capacitors. In recent years, the fabrication of one-dimension (1D) ferroelectric (FE) nanostructures have been investigated as a capacitor for future 3D memories, however several difficulties need to be overcome in particular fabrication and characterization. In this work, the fabrication of ferroelectrics (FE) (e.g., Pb1-xZrxTiO3 (PZT) and BaTiO3 (BT)) multi-walled carbon nanotubes (MWCNTs) composites were synthesised by chemical solution deposition (CSD) method, namely sol gel. Later, the composites were investigated using scanning electron microscope (SEM) equipped with energy dispersive spectroscopy facilities and transmission electron microscopy (TEM) in addition to X Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR), to address the compatibility between FE and CNTs.

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