scholarly journals Electrochemical Improvement of the MWCNT/Al Electrodes for Supercapacitors

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7612
Author(s):  
Arkady N. Redkin ◽  
Alena A. Mitina ◽  
Eugene E. Yakimov ◽  
Evgeny N. Kabachkov
Keyword(s):  
Carbon Nanotubes ◽  
Electrochemical Oxidation ◽  
Photoelectron Spectroscopy ◽  
Electrical Contact ◽  
Specific Capacity ◽  
Chemical Deposition ◽  
Multiwall Carbon Nanotubes ◽  
Aluminum Foil ◽  
Ethanol Vapor ◽  
Electrodes For Supercapacitors

An original technique of chemical deposition (CVD) by catalytic pyrolysis of ethanol vapor was used to directly grow multiwall carbon nanotubes (MWCNTs) layers on aluminum foil. The grown nanotubes had excellent adhesion and direct electrical contact to the aluminum substrate. This material was perfect for use in electrochemical supercapacitors. In this work, the possibility of a significant increase in the specific capacity of MWCNTs by simple electrochemical oxidation was investigated. The optimal conditions for improving the characteristics of the MWCNT/Al electrodes were found. Electrochemical treatment of MWCNT/Al electrodes in a 0.005 M Na2SO4 solution at a potential of 4–5 V for 20–30 min increased the specific capacity of MWCNTs from 30 F/g to 140 F/g. The properties of modified nanotubes were investigated by X-ray photoelectron spectroscopy, cyclic voltammetry (CV), and impedance spectroscopy. A significant increase in the concentration of oxygen-containing functional groups on the surface of MWCNTs was found as a result of electrochemical oxidation. The modified MWCNT/Al electrodes maintained excellent stability to multiple charge–discharge cycles. After 20,000 CVs, the capacity loss was less than 5%. Thus, the results obtained significantly expanded the possibilities of using MWCNT/Al composite materials obtained by the method of direct deposition of carbon nanotubes on aluminum foil as electrodes for supercapacitors.

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.

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.

One-step Synthesis of Carbon Nanotubes Network with Rich Oxygenated Functional Groups via Microwave Plasma in Atmospheric Pressure

MRS Advances ◽  
2020 ◽  
Vol 5 (52-53) ◽  
pp. 2679-2684
Author(s):  
Dashuai Li ◽  
Ling Tong ◽  
Bo Gao
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Functional Groups ◽  
Photoelectron Spectroscopy ◽  
Atmospheric Pressure ◽  
Microwave Plasma ◽  
Ethanol Vapor ◽  
Transmission Electron ◽  
Synthesis Of Carbon Nanotubes ◽  
Oxygenated Functional Groups

AbstractAn atmospheric pressure microwave plasma tubular furnace apparatus (MPTF) for the rapid synthesis of carbon nanotubes (CNTs) has been developed. CNTs have been synthesized by an Argon-Hydrogen microwave plasma using ethanol vapor as carbon source with the furnace temperature of 800 °C at the atmospheric pressure. The synthesized CNTs have been analyzed by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and are shown to be multi-walled and tangled and chemically connected to form a high-density network with the diameter at the range of 25-70 nm. The measurement of X-ray photoelectron spectroscopy (XPS) indicates that a large number of oxygenated functional groups grown on the surface of CNTs. These properties proved that the CNTs could be utilized as nanoscale templates for various applications.

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

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.

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.

scholarly journals Hydrothermally Assisted Synthesis of Porous Polyaniline@Carbon Nanotubes–Manganese Dioxide Ternary Composite for Potential Application in Supercapattery

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2918
Author(s):  
Javed Iqbal ◽  
Mohammad Omaish Ansari ◽  
Arshid Numan ◽  
S. Wageh ◽  
Ahmed Al-Ghamdi ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Manganese Dioxide ◽  
Photoelectron Spectroscopy ◽  
Oxidative Polymerization ◽  
Specific Capacity ◽  
Cyclic Stability ◽  
X Ray Diffraction ◽  
Ternary Composite ◽  
X Ray ◽  
Synthesis Methodology

In this study, ternary composites of polyaniline (PANI) with manganese dioxide (MnO2) nanorods and carbon nanotubes (CNTs) were prepared by employing a hydrothermal methodology and in-situ oxidative polymerization of aniline. The morphological analysis by scanning electron microscopy showed that the MnO2 possessed nanorod like structures in its pristine form, while in the ternary PANI@CNT/MnO2 composite, coating of PANI over CNT/MnO2, rods/tubes were evidently seen. The structural analysis by X-ray diffraction and X-ray photoelectron spectroscopy showed peaks corresponding to MnO2, PANI and CNT, which suggested efficacy of the synthesis methodology. The electrochemical performance in contrast to individual components revealed the enhanced performance of PANI@CNT/MnO2 composite due to the synergistic/additional effect of PANI, CNT and MnO2 compared to pure MnO2, PANI and PANI@CNT. The PANI@CNT/MnO2 ternary composite exhibited an excellent specific capacity of 143.26 C g−1 at a scan rate of 3 mV s−1. The cyclic stability of the supercapattery (PANI@CNT/MnO2/activated carbon)—consisting of a battery type electrode—demonstrated a gradual increase in specific capacity with continuous charge–discharge over ~1000 cycles and showed a cyclic stability of 119% compared to its initial value after 3500 cycles.

Preparation and Characterization of Multiwalled Carbon Nanotubes Deposited by Europium Hydroxide

2011 ◽  
Vol 418-420 ◽  
pp. 428-435
Author(s):  
Shao Ming Fang ◽  
Jia You Tang ◽  
Li Jun Gao ◽  
Li Ming Zhou
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
High Resolution ◽  
Functional Groups ◽  
Photoelectron Spectroscopy ◽  
Ph Value ◽  
Multiwall Carbon Nanotubes ◽  
Europium Nitrate ◽  
Multiwalled Carbon ◽  
X Ray

In this paper, europium hydroxide (Eu(OH)3) was introduced onto multiwall carbon nanotubes (MWCNTs) by the MWCNTs and europium nitrate (Eu(NO3)3•6H2O) on a mild conditions in the alkalescence solution. The influence of the different pH value on the product was analyzed. Characterizations of the products were performed using raman spectroscopy, X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high resolution thermal field emission scanning electron microscopy (FE-SEM), and high resolution transmission electron microscopy (HR-TEM). Those results indicated that oxygen-containing groups such as -OH, -C=O, and -COOH generated on the surface of the MWCNTs treated with nitric acid. Those functional groups can attract Eu, and provide the position to Eu(OH)3. When the pH value situation of the reaction is 7-8, the MWCNTs deposited by Eu(OH)3 were obtained. Furthermore, there is the weak interaction between Eu and the functional groups of the MWCNTs. In addition, the integrity of the MWCNTs was not damaged during the whole preparation.

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