scholarly journals Carbon Micronymphaea: Graphene on Vertically Aligned Carbon Nanotubes

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Jong Won Choi ◽  
Seul Ki Youn ◽  
Hyung Gyu Park
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanomaterials ◽  
Chemical Vapor ◽  
Structural Features ◽  
Hybrid Structure ◽  
Operating Conditions ◽  
One Pot ◽  
Vertical Arrays ◽  
Carbon Precipitation ◽  
Grown Graphene

This paper describes the morphology of carbon nanomaterials such as carbon nanotube (CNT), graphene, and their hybrid structure under various operating conditions during a one-step synthesisviaplasma-enhanced chemical vapor deposition (PECVD). We focus on the synthetic aspects of carbon hybrid material composed of heteroepitaxially grown graphene on top of a vertical array of carbon nanotubes, called carbon micronymphaea. We characterize the structural features of this unique nanocomposite by uses of electron microscopy and micro-Raman spectroscopy. We observe carbon nanofibers, poorly aligned and well-aligned vertical arrays of CNT sequentially as the growth temperature increases, while we always discover the carbon hybrids, called carbon micronymphaea, at specific cooling rate of 15°C/s, which is optimal for the carbon precipitation from the Ni nanoparticles in this study. We expect one-pot synthesized graphene-on-nanotube hybrid structure poses great potential for applications that demand ultrahigh surface-to-volume ratios with intact graphitic nature and directional electronic and thermal transports.

Sulfonated multiwalled carbon nanotubes (MWCNTs) as a new, efficient, and recyclable heterogeneous nanocatalyst for the synthesis of amines

2012 ◽  
Vol 90 (8) ◽  
pp. 701-707 ◽  
Author(s):  
M. M. Doroodmand ◽  
S. Sobhani ◽  
A. Ashoori
Keyword(s):  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Chemical Vapor ◽  
Catalytic Amount ◽  
Multiwalled Carbon ◽  
One Pot ◽  
Heterogeneous Nanocatalyst ◽  
Aldehydes And Ketones ◽  
Simple Filtration

Sulfonated multiwalled carbon nanotubes (MWCNTs) were synthesized by chemical vapor deposition (CVD) as a new and facile one-pot method using acetylene (as the CNT precursor), thiophene (as the sulfur precursor), and ferrocene (for in situ liberation of metal nanoparticles as the CNT nanocatalyst). A low catalytic amount of the resulting sulfonated MWCNTs with a turnover number (TON) up to 980 and a turnover frequency (TOF) up to 11 160 h–1 was utilized as a new and recyclable heterogeneous nanocatalyst for the efficient one-pot synthesis of various amines (secondary and tertiary) by direct reductive amination of aldehydes and ketones using NaBH4. The catalyst was easily isolated from the reaction mixture by simple filtration and reused at least five times without significant degradation in activity.

scholarly journals Growth Mechanism of a Hybrid Structure Consisting of a Graphite Layer on Top of Vertical Carbon Nanotubes

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Nicolo' Chiodarelli ◽  
Cigang Xu ◽  
Olivier Richard ◽  
Hugo Bender ◽  
Alexander Klekachev ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Growth Conditions ◽  
Hybrid Structure ◽  
Carbon Layer ◽  
Time Dynamic ◽  
Catalyst Film ◽  
Optical And Electronic Properties ◽  
Deposition Processes

Graphene and carbon nanotubes (CNTs) are both carbon-based materials with remarkable optical and electronic properties which, among others, may find applications as transparent electrodes or as interconnects in microchips, respectively. This work reports on the formation of a hybrid structure composed of a graphitic carbon layer on top of vertical CNT in a single deposition process. The mechanism of deposition is explained according to the thickness of catalyst used and the atypical growth conditions. Key factors dictating the hybrid growth are the film thickness and the time dynamic through which the catalyst film dewets and transforms into nanoparticles. The results support the similarities between chemical vapor deposition processes for graphene, graphite, and CNT.

Mathematical Modeling of Carbon Nanotubes Formation in Fluidized Bed Chemical Vapor Deposition

2017 ◽  
Vol 15 (2) ◽  
Author(s):  
Firoozeh Danafar ◽  
Said S. Elnashaie ◽  
Hassan Hashemipour ◽  
Mohammad Ali Rostamizadeh
Keyword(s):  
Mathematical Modeling ◽  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Fluidized Bed ◽  
Vapor Deposition ◽  
Active Sites ◽  
Catalyst Activity ◽  
Chemical Vapor ◽  
Operating Conditions ◽  
Catalyst Loading

Abstract This study investigates mathematical modeling of carbon nanotubes (CNTs) formation on catalyst particulate in a fluidized bed chemical vapor deposition (FBCVD) reactor. The mass of CNTs formed corresponds to the catalyst activity directly. The catalyst deactivation occurs as active sites are occupied by CNTs and thus causes unsteady state behavior of the process. The effects of catalyst loading (as bed height) as well as reaction temperature on the reaction progressing were investigated. The model, validated with our experimental data, indicates a good accuracy to predict the yield of CNTs formation for a given operating conditions. The model presented also can predict the optimized time as well as the suitable amount of catalyst loading to produce CNTs for a given reactor conditions.

scholarly journals Synthesis, Properties, and Applications of Low-Dimensional Carbon-Related Nanomaterials

2011 ◽  
Vol 2011 ◽  
pp. 1-21 ◽  
Author(s):  
Ali Mostofizadeh ◽  
Yanwei Li ◽  
Bo Song ◽  
Yudong Huang
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanomaterials ◽  
Experimental Studies ◽  
Structural Features ◽  
Two Dimensional ◽  
One Dimensional ◽  
Synthesis Properties ◽  
Carbon Nanowalls ◽  
Low Dimensional ◽  
Carbon Encapsulated Metal Nanoparticles

In recent years, many theoretical and experimental studies have been carried out to develop one of the most interesting aspects of the science and nanotechnology which is called carbon-related nanomaterials. The goal of this paper is to provide a review of some of the most exciting and important developments in the synthesis, properties, and applications of low-dimensional carbon nanomaterials. Carbon nanomaterials are formed in various structural features using several different processing methods. The synthesis techniques used to produce specific kinds of low-dimensional carbon nanomaterials such as zero-dimensional carbon nanomaterials (including fullerene, carbon-encapsulated metal nanoparticles, nanodiamond, and onion-like carbons), one-dimensional carbon nanomaterials (including carbon nanofibers and carbon nanotubes), and two-dimensional carbon nanomaterials (including graphene and carbon nanowalls) are discussed in this paper. Subsequently, the paper deals with an overview of the properties of the mainly important products as well as some important applications and the future outlooks of these advanced nanomaterials.

The enthalpies of formation of carbon nanomaterials as a key factor for understanding their structural features

2017 ◽  
Vol 19 (3) ◽  
pp. 2269-2275 ◽  
Author(s):  
E. V. Suslova ◽  
S. V. Savilov ◽  
J. Ni ◽  
V. V. Lunin ◽  
S. M. Aldoshin
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanomaterials ◽  
Structural Features ◽  
Enthalpies Of Formation ◽  
Key Factor ◽  
Carbon Nanoflakes

Carbon nanomaterials (CNMs), such as carbon nanotubes (CNTs), carbon nanoflakes (CNFs) and their N-doped derivatives, show sufficient correlations between structure, composition and properties.

scholarly journals Promoting Role of Amorphous Carbon and Carbon Nanotubes Growth Modes of Methane Decomposition in One-Pot Catalytic Approach

Catalysts ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1217
Author(s):  
Lifang Chen ◽  
Luis Enrique Noreña ◽  
Jin An Wang ◽  
Roberto Limas ◽  
Ulises Arellano ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Amorphous Carbon ◽  
Interaction Strength ◽  
Formation Mechanisms ◽  
One Pot ◽  
Growth Modes ◽  
Initial Stage ◽  
Support Reaction ◽  
Production Of Hydrogen ◽  
Carbon Precipitation

We report the simultaneous production of hydrogen fuel and carbon nanotubes (CNTs) via methane dehydrogenation catalyzed with Ni/SBA-15. Most Ni nanoparticles (NPs) with size between 10 and 30 nm were highly dispersed on SBA-15 and most of them had a strong interaction with the support. At temperatures ranging from 500 to 800 °C, methane could be decomposed to release hydrogen with 100% selectivity at conversion between 51 and 65%. There was no CO or CO2 detectable in the reaction fluent. In the initial stage of the reaction, amorphous carbon and dehydrogenated methane species adsorbed on the Ni NPs promoted the CH4 decomposition. The amorphous carbon atoms were then transformed into carbon nanotubes which chiefly consisted of a multiwall structure and grew towards different orientations via a tip-growth or a base-growth modes, controlled by the interaction strength between the Ni NPs and the SBA-15 support. Reaction temperature affected not only methane conversion, but also the diffusion of carbon atoms on/in the Ni NPs and their precipitation at the interfaces. At higher temperature, bamboo-like CNTs or onion-like metal-encapsulated carbons were formed, mainly due to the rate of carbon atom formation greater than that of carbon precipitation for CNTs construction. The CNTs formation mechanisms are discussed and their growth modes under different conditions are proposed.

scholarly journals Production of carbon nanotubes and their functionalization

2020 ◽  
pp. 26-31
Author(s):  
Meruyert Nazhipkyzy ◽  
Nazgul Kuantai
Keyword(s):  
Carbon Nanotubes ◽  
Surface Layer ◽  
Carbon Nanomaterials ◽  
Multiwall Carbon Nanotubes ◽  
Chemical Vapor ◽  
Optical Microscope ◽  
Qualitative Assessment ◽  
Hydroxyl Groups ◽  
Sand Surface ◽  
Synthesis Of Carbon Nanotubes

In this work, the synthesis of carbon nanotubes was carried out on the sand surface with hydrophobic properties by chemical vapor deposition (CVD). The effective temperature for the synthesis of carbon nanotubes is 800 °C. Propane-butane gas mixture was used as a source of gaseous carbon. Argon gas (Ar) was used as an inert carrier gas. Nickel nitrate (Ni(NO3)2) was chosen as a catalyst for producing carbon nanotubes. Despite all the special properties of carbon nanomaterials, one of the problems with its use is its tendency to agglomerate and inert to the matrix of various substances. In order to solve this problem, the chemical functionalization of the surface layer of multiwall carbon nanotubes was carried out. To introduce carboxyl groups into the surface layer of carbon nanotubes, its surface was treated with a concentrated mixture of acids H2SO4/HNO3. It has been established that the main part of the functional groups in the surface layer of nanotubes are carboxyl, carbonyl and hydroxyl groups. Carbon nanotubes synthesized on the surface of hydrophobic sand were analyzed by the following research methods: scanning electron microscope, optical microscope, elemental analysis, Raman spectroscopy and a qualitative assessment of functionalized nanotubes using IR spectroscopy.

Dual growth of graphene nanoplatelets and carbon nanotubes hybrid structure via chemical vapor deposition of methane over Fe–MgO catalysts

2019 ◽  
Vol 28 (6) ◽  
pp. 435-445
Author(s):  
Omnia M. El-Ahwany ◽  
Ahmed E. Awadallah ◽  
Ateyya A. Aboul-Enein ◽  
Samira M. Abdel-Azim ◽  
Noha A.K. Aboul-Gheit ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Hybrid Structure ◽  
Graphene Nanoplatelets

scholarly journals Effects of Gas Composition in Producing Carbon Nanomaterials by Plasma Enhanced Chemical Vapor Deposition

2022 ◽  
Vol 2152 (1) ◽  
pp. 012052
Author(s):  
Chen Yang
Keyword(s):  
Carbon Nanotubes ◽  
Vapor Deposition ◽  
Carbon Nanomaterials ◽  
Chemical Vapor ◽  
Gas Composition ◽  
New Materials ◽  
Important Method ◽  
Growth Regime ◽  
Factors Influencing ◽  
Carbon Nanowalls

Abstract Carbon nanomaterials are becoming new materials which can be used in many fields including transistors, sensors, displays, hydrogen storage, capacitors, catalyst supporters and so on. PECVD is an important method for producing carbon nanomaterials. However, it remains a challenge to control the final production of the PECVD process. This paper tries to figure out the gas factors influencing the growth of different carbon nanomaterials. This paper begins with a brief introduction of PECVD and the growth regime of carbon nanowalls and carbon nanotubes. It discusses how the Argon, carbon source, hydrogen and other gas affect the growth of CNMs. The paper ends with a discussion on the practical influence of confirming the function of each gas.

Carbon nanotubes and carbon nanobeads synthesis by one-pot chemical vapor deposition method: morphology and crystallinity

2018 ◽  
Vol 5 (8) ◽  
pp. 085008 ◽  
Author(s):  
Jael Madaí Ambriz-Torres ◽  
Francisco Gabriel Granados-Martínez ◽  
José de Jesús Contreras-Navarrete ◽  
Carmen Judith Gutiérrez-García ◽  
Diana Litzajaya García-Ruiz ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Chemical Vapor Deposition Method ◽  
Deposition Method ◽  
One Pot
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