Journal articles: 'Synthesis of carbon nanotubes (CNTs)'

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Sun, Xiao Gang, Zhi Wen Qiu, Long Chen, et al. "Industrial Synthesis of Whisker Carbon Nanotubes." Materials Science Forum 852 (April 2016): 514–19. http://dx.doi.org/10.4028/www.scientific.net/msf.852.514.

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Since the first observation of carbon nanotubes (CNTs) in 1991, their synthesis techniques has been extensively investigated. The chemical vapor deposition (CVD) process have attracted much attention because of both their versatility and easy large scale production for CNTs . This paper is focused on a catalytic CVD-based method for synthesis of whisker multiwalled carbon nanotubes (WMWCNTs). The new type of carbon nanotube is similar to the whisker. The morphology of the WMWCNTs are very different from traditional carbon nanotubes prepared by traditional chemical vapor deposition process. The traditional CNTs were twisted and entangled with each other. These suggested that there are a lot of deficiencies on the CNTs and are difficult to disperse in matrix materials. The as-produced WMWCNTs are very straight and not entangled with each other. The line structure means that WMWCNTs are easily dispersed in matrix materials than traditional CNTs which are twined together. The crystallinity of WMWCNTs increased to 96% which was much higher than traditional CNTs after graphitization treatment at 2800°C.

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Kang, Ning, Jin Hua, Lizhen Gao, Bin Zhang, and Jiewen Pang. "The Interplay between Whey Protein Fibrils with Carbon Nanotubes or Carbon Nano-Onions." Materials 14, no. 3 (2021): 608. http://dx.doi.org/10.3390/ma14030608.

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Whey protein isolate (WPI) fibrils were prepared using an acid hydrolysis induction process. Carbon nanotubes (CNTs) and carbon nano-onions (CNOs) were made via the catalytic chemical vapor deposition (CVD) of methane. WPI fibril–CNTs and WPI fibril–CNOs were prepared via hydrothermal synthesis at 80 °C. The composites were characterized by SEM, TEM, FTIR, XRD, Raman, and TG analyses. The interplay between WPI fibrils and CNTs and CNOs were studied. The WPI fibrils with CNTs and CNOs formed uniform gels and films. CNTs and CNOs were highly dispersed in the gels. Hydrogels of WPI fibrils with CNTs (or CNOs) could be new materials with applications in medicine or other fields. The CNTs and CNOs shortened the WPI fibrils, which might have important research value for curing fibrosis diseases such as Parkinson’s and Alzheimer’s diseases. The FTIR revealed that CNTs and CNOs both had interactions with WPI fibrils. The XRD analysis suggested that most of the CNTs were wrapped in WPI fibrils, while CNOs were partially wrapped. This helped to increase the biocompatibility and reduce the cytotoxicity of CNTs and CNOs. HR-TEM and Raman spectroscopy studies showed that the graphitization level of CNTs was higher than for CNOs. After hybridization with WPI fibrils, more defects were created in CNTs, but some original defects were dismissed in CNOs. The TG results indicated that a new phase of WPI fibril–CNTs or CNOs was formed.

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Kumar, Arun. "Natural Materials—Interesting Candidates for Carbon Nanomaterials." Physchem 1, no. 1 (2021): 4–25. http://dx.doi.org/10.3390/physchem1010002.

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This review sums up the techniques used for the synthesis of carbon nanotubes (CNTs), carbon nanofibers (CNFs), and carbon nanospheres (CNSs) by employing catalysts of natural origin. Establishing large-scale production and commercial applications of CNTs for a sustainable society is still of high apprehension. In this regard, one of the major factors is the starting materials such as precursors and catalyst sources. However, natural materials contain a minor quantity of metals or metal oxides and could be employed as a catalyst source for the synthesis of CNTs, providing the possibility to replace expensive catalyst sources. A large number of successful studies have been completed so far and confirm that these developed methods for carbon nanomaterials synthesis exhibiting high quality from common natural materials are not only possible but, most importantly, promising and scalable. This review also highlights purification methods and recent promising applications of as-synthesized CNTs.

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Thurakitseree, Theerapol, and Chupong Pakpum. "Low-Cost Sputtering Process for Carbon Nanotubes Synthesis." Applied Mechanics and Materials 891 (May 2019): 195–99. http://dx.doi.org/10.4028/www.scientific.net/amm.891.195.

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According to their wonderful properties, carbon nanotubes (CNTs) have been well known for decades. The synthesis process and catalyst deposition method have also drawn attention to control the nanotube structure and properties. Sputtering method is then one promising option to grow the nanotubes in mass production. This method is, however, still costly. Here, we have presented a simple low-cost custom-made DC magnetron sputtering for catalyst thin film deposition. Three different metal thin films (Fe, Ni, Cu) deposited on Si substrates have been employed to investigate nanotube production. Prior to deposition of the catalysts, Al was used as supporting layer. (Al/Fe, Al/Ni, Al/Cu). CNTs were grown by chemical vapor deposition process at 800°C. Ethanol was preliminary used as a carbon source. It was found that CNTs could be successfully grown from only Al/Ni catalysts in our system with the diameter of approximately 200 nm, where the rest of samples were not observed. In addition, vertical-aligned CNTs with the thickness of about 10 μm could be obtained when acetylene was replaced instead of ethanol with reducing partial pressure of the feedstock. A large D-band at 1338 cm-1 with broader G-band at 1582 cm-1 from Raman spectra give a rise to multi layers growth of sp2 carbon walls. Such dimension suggests that it is the characteristic of multi-walled carbon nanotubes.

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Sahu, Anamika, Aviral Jain, and Arvind Gulbake. "THE ROLE OF CARBON NANOTUBES IN NANOBIOMEDICINES." International Journal of Pharmacy and Pharmaceutical Sciences 9, no. 6 (2017): 235. http://dx.doi.org/10.22159/ijpps.2017v9i6.18522.

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CNTs is a fullerene molecule, described in 1991 by the Japanese Scientist ‘‘Sumio Iijima’’ as tube-shaped of graphitic carbon, can be obtained either single or multi-walled nanotube, having a diameter measuring on the nanometer scale, and generally known as buckytubes. Carbon nanotubes (CNTs) have established much recent interest as new entities for experimental disease diagnosis and treatment because of their unique electronic, mechanical, thermal, spectroscopic, metallic, semiconducting and superconducting electron transport properties. Carbon nanotubes can be acquired in numerous ways, the general techniques are Arc discharge, Laser ablation, and Chemical vapour deposition (CVD). Carbon nanotubes are discussed in this review in terms of characters, history, structures, properties, synthesis, purification, characterization methods, toxicity and applications. Purification of nanotubes includes many techniques: Acid treatment, oxidation, annealing, ultrasonication, cutting, magnetic purification, chromatography techniques. Further functionalization enhanced the water solubility of CNT's and completely transformed their biocompatibility profile. Carbon nanotubes, due to their large surface areas, unique surface properties, and needle-like shape, can deliver a lot of therapeutic agents, including DNA, siRNAs and proteins to the target disease sites. CNTs can be readily excreted through the renal route by means of degradation through myeloperoxidase (MOP) enzyme. As CNTs have attracted the fancy of many scientists worldwide, the work beyond our expectations and their simple mechanism with long lasting life makes it more reliable to use. The unique and unusual properties of these structures make them a unique material with a whole range of promising applications.

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Wiak, Sławomir, Anna Firych-Nowacka, Krzysztof Smółka, Łukasz Pietrzak, Zbigniew Kołaciński, and Łukasz Szymański. "Induction heating process of ferromagnetic filled carbon nanotubes based on 3-D model." Open Physics 15, no. 1 (2017): 1061–66. http://dx.doi.org/10.1515/phys-2017-0134.

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AbstractSince their discovery by Iijima in 1991 [1], carbon nanotubes have sparked unwavering interest among researchers all over the world. This is due to the unique properties of carbon nanotubes (CNTs). Carbon nanotubes have excellent mechanical and electrical properties with high chemical and thermal stability. In addition, carbon nanotubes have a very large surface area and are hollow inside. This gives a very broad spectrum of nanotube applications, such as in combination with polymers as polymer composites in the automotive, aerospace or textile industries. At present, many methods of nanotube synthesis are known [2, 3, 4, 5, 6]. It is also possible to use carbon nanotubes in biomedical applications [7, 8, 9, 10, 11, 12, 13, 14], including the destruction of cancer cells using iron-filled carbon nanotubes in the hyperthermia process. Computer modelling results of Fe-CNTs induction heating process are presented in the paper. As an object used for computer model creation, Fe-CNTs were synthesized by the authors using CCVD technique.

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Liu, Yuan Chao, Bao Min Sun, and Zhao Yong Ding. "Catalyst Assisted Synthesis of Carbon Nanotubes Using the V-Shaped Pyrolysis Flame Method." Advanced Materials Research 79-82 (August 2009): 2123–26. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.2123.

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Flames offer potential for synthesis of carbon nanotubes(CNTs) in large quantities at considerably lower costs than that of other methods currently available. Synthesis CNTs from V-shaped pyrolysis flame is a kind of novel technique. This study aims to examine conditions for CNTs formation in V-shaped pyrolysis flame. Synthesis inner the V-shaped body and providing heat outer is distinct characteristic in the method. A premixed carbon monoxide/hydrogen gas diluted by helium gas flow was introduced into V-shaped body bottom centre. Simultaneously, as catalyst precursor, pentacarbonyl iron was entrained after ultrasonic atomization into the central pipe by helium gas flow. The rich acetylene/air premixed gas, providing heat source, was introduced into V-shaped body outside surface. Scanning electron microscopy and transmission electron microscopy images of the carbon products were examined. Large quantities of CNTs with the less carbon impurities were formed in the process. Carbon nanotubes can grow well when the sampling time was 5 minutes.A nanotube formation ‘window’ is evident with formation limited to fuel equivalence ratios between 1.6 and 1.8. Furthermore, temperature range was from 850°C to 950°C.Nanoparticles associated with nanotube bundles were identified as primarily ferric oxide.

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Mudimela, Prasantha R., Larisa I. Nasibulina, Albert G. Nasibulin, et al. "Synthesis of Carbon Nanotubes and Nanofibers on Silica and Cement Matrix Materials." Journal of Nanomaterials 2009 (2009): 1–4. http://dx.doi.org/10.1155/2009/526128.

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In order to create strong composite materials, a good dispersion of carbon nanotubes (CNTs) and nanofibers (CNFs) in a matrix material must be obtained. We proposed a simple method of growing the desirable carbon nanomaterial directly on the surface of matrix particles. CNTs and CNFs were synthesised on the surface of model object, silica fume particles impregnated by iron salt, and directly on pristine cement particles, naturally containing iron oxide. Acetylene was successfully utilised as a carbon source in the temperature range from 550 to750∘C. 5–10 walled CNTs with diameters of 10–15 nm at600∘Cand 12–20 nm at 750∘Cwere synthesised on silica particles. In case of cement particles, mainly CNFs with a diameter of around 30 nm were grown. It was shown that high temperatures caused chemical and physical transformation of cement particles.

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Itami, Kenichiro. "Toward controlled synthesis of carbon nanotubes and graphenes." Pure and Applied Chemistry 84, no. 4 (2012): 907–16. http://dx.doi.org/10.1351/pac-con-11-11-15.

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A bottom-up synthesis of structurally uniform carbon nanotubes (CNTs) and graphenes is recognized as one of the greatest challenges of primary importance in nanocarbon science. This paper highlights our efforts to address these challenges since 2005. These endeavors have led to (i) modular, size-selective, and scalable synthesis of [n]cycloparapheneylenes (CPPs), the shortest segment of armchair CNTs, (ii) design and synthesis of the shortest segment of chiral CNTs, and (iii) efficient synthesis of carbon nanosheets through catalytic C–H bond arylation of polycyclic aromatic hydrocarbons (PAHs). We consider these works as a possible first step toward a controlled synthesis of structurally uniform CNTs and nanographenes.

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Tan, Win Hon, Siew Ling Lee, and Cheng Tung Chong. "TEM and XRD Analysis of Carbon Nanotubes Synthesised from Flame." Key Engineering Materials 723 (December 2016): 470–75. http://dx.doi.org/10.4028/www.scientific.net/kem.723.470.

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A premixed flame burner system was utilised to synthesise carbon nanotubes (CNTs). The morphologies of highly-graphitic carbon nanotubes were characterised by using transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). The XRD analysis shows the spectrum of a typical CNT, while TEM imaging shows the physical structure of the carbon nanotubes. CNTs were grown effectively on a Ni-contained substrate in an elevated temperature environment. The flame synthesised CNTs were of high crystalline, multi-wall structure, and contained relatively less impurities and amorphous carbon. The CNT intershell spacing values quantified using TEM and XRD are 0.317 nm and 0.344 nm respectively. CNTs produced from flame synthesis are based on the tip-growth model and vapor-liquid-solid (VLS) mechanism.

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Chun, Charles Ng Wai, Husnul Azan Tajarudin, Norli Ismail, Baharin Azahari, Muaz Mohd Zaini Makhtar, and Leong Kah Yan. "Bacterial Flagellum versus Carbon Nanotube: A Review Article on the Potential of Bacterial Flagellum as a Sustainable and Green Substance for the Synthesis of Nanotubes." Sustainability 13, no. 1 (2020): 21. http://dx.doi.org/10.3390/su13010021.

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Bacterial flagella are complex multicomponent structures that help in cell locomotion. It is composed of three major structural components: the hook, the filament and basal body. The special mechanical properties of flagellar components make them useful for the applications in nanotechnology especially in nanotube formation. Carbon nanotubes (CNTs) are nanometer scale tube-shaped material and it is very useful in many applications. However, the production of CNTs is costly and detrimental to the environment as it pollutes the environment. Therefore, bacterial flagella have become a highly interesting research area especially in producing bacterial nanotubes that could replace CNTs. In this review article, we will discuss about bacterial flagellum and carbon nanotubes in the context of their types and applications. Then, we will focus and review on the characteristics of bacterial flagellum in comparison to carbon nanotubes and subsequently, the advantages of bacterial flagellum as nanotubes in comparison with carbon nanotubes.

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Zhou, Zhengping, Xiang-Fa Wu, and Haoqing Hou. "Electrospun carbon nanofibers surface-grown with carbon nanotubes and polyaniline for use as high-performance electrode materials of supercapacitors." RSC Adv. 4, no. 45 (2014): 23622–29. http://dx.doi.org/10.1039/c4ra00964a.

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This paper reports the synthesis and electrochemical performance of carbon nanofibers (CNFs) surface-grown with carbon nanotubes (CNTs) and nanostructured polyaniline (PANI) films, i.e., PANI/CNT/CNF, for use as a high-performance electrode material of pseudosupercapacitors.

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Harris, A. T., C. H. See, J. Liu, O. Dunens, and K. Mackenzie. "Towards the Large-Scale Synthesis of Carbon Nanotubes in Fluidised Beds." Journal of Nanoscience and Nanotechnology 8, no. 5 (2008): 2450–57. http://dx.doi.org/10.1166/jnn.2008.118.

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Carbon nanotubes (CNTs) are a form of crystalline carbon with extraordinary properties, making them valuable in a broad range of applications. However, the lack of suitable large-scale manufacturing techniques, which we define as being of the order 10000 tonnes per annum, continues to inhibit their widespread use. Of the three established synthesis methods for CNTs: (i) chemical vapour deposition (CVD), (ii) laser ablation, and (iii) arc discharge, CVD techniques show the greatest promise for economically viable, large-scale synthesis. In particular, the fluidised bed CVD (FBCVD) technique, where the CVD reaction occurs within a fluidised bed of catalyst particles, has the potential to produce high quality CNTs, inexpensively, in large quantities. In this work we report on the development of a catalytic chemical vapour deposition process, using batch fluidised bed reactors, for the synthesis of straight and spiral carbon nanotubes at pilot scale (up to 1 kg/hr). We believe this to be the first report of the synthesis of spiral carbon nanotubes using fluidised bed CCVD. Iron, nickel and cobalt transition metal catalysts supported on non-porous alumina substrates were fluidised in a mixture of nitrogen, hydrogen and ethylene at temperatures between 550 and 800 C for between 15 and 90 minutes. Nanotube yield was inferred from thermogravimetric analysis and the quality and size of the CNTs from transmission electron microscopy. Conflicting information in the literature about the influence of synthesis parameters on CNT properties suggests that further investigation is necessary to understand the synthesis process at a fundamental level, i.e., independent of reactor design and operation.

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Shchegolkov, Alexander V., Elena A. Burakova, Tatyana P. Dyachkova, Natalia V. Orlova, Fadej F. Komarov, and Mikhail S. Lipkin. "SYNTHESIS AND FUNCTIONALIZATION OF CARBON NANOTUBES FOR SUPERCAPACITOR ELECTRODES." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 63, no. 7 (2020): 74–81. http://dx.doi.org/10.6060/ivkkt.20206307.6239.

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Carbon nanotubes (CNTs) have been synthesized using catalysts of the Ni/Mg, Fe-Co/Al2O and Co-Mo/Al2O3-MgO composition with different component ratios by gas-phase chemical deposition. They differ in geometric parameters, the nature of the inclusion of metal oxide catalyst impurities, and morphological features. To form oxygen-containing functional groups on the surface, CNTS were oxidized with ozone-oxygen mixture (1 vol.% O3) at room temperature for 5 h. Initial and functionalized CNT samples were characterized by scanning and transmission electron microscopy, Raman and IR spectroscopy. It is shown that as a result of oxidation, the amorphous phase is removed from the material, and oxygen-containing groups-OH, >C=O and –O–C–O–are formed on the CNT surface. Also, during functionalization, there is a slight decrease in the specific surface area of the studied nanotube samples. The electrochemical behavior of initial and functionalized carbon nanotubes in an alkaline electrolyte was studied using cyclic voltammetry. It is shown that based on the analysis of CVA curves, CNTS can be divided into two groups-with the Faraday and non-Faraday character of the current electrode processes. The contribution of the non-Faraday component prevails when carbon nanotubes synthesized on Ni/Mg and Co-Mo/Al2O3-MgO catalysts are used as electrode materials. Oxidative functionalization of CNTs of this type is appropriate and contributes to the improvement and stabilization of capacitance properties during cycling. The positive influence of metal oxide catalyst admixtures on the properties of electrode materials was also noted. Therefore, ozone oxidation is a promising way to functionalize CNTs for their subsequent use as electrode materials for electrochemical capacitors.

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Gautam, Ujjal K., Yoshio Bando, Pedro M. F. J. Costa, et al. "Inorganically filled carbon nanotubes: Synthesis and properties." Pure and Applied Chemistry 82, no. 11 (2010): 2097–109. http://dx.doi.org/10.1351/pac-con-09-12-08.

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Since the discovery of carbon nanotubes (CNTs) in 1991, widespread research has been carried out to understand their useful physical and electronic properties and also to explore their use in devices. CNTs have many unique properties such as tunable electrical resistance, mechanical robustness, and high thermal conductivity, which when combined with other inorganic materials such as phosphors or superconductors could lead to hetero-structures with diverse functionality. We have been able to obtain mass production of such materials wherein CNTs form core-shell heterostructures with metals, semiconductors, insulators, and even metal-semiconductor heterojunctions. The emerging strategy employs a high-temperature chemical vapor deposition (CVD) technique and high heating rates. Interestingly, due to their high temperature stability, CNTs can act as a nanoreactor for production of exotic materials inside it. In this article, we take ZnS-filled CNTs as an example to explain our synthesis strategy. We explore the optical behavior of these complex materials, analyzing both their luminescence and degradation upon exposure to an electron beam. In addition, the mechanical response of filled CNTs has been evaluated individually inside a transmission electron microscope fitted with an atomic force microscopy–transmission electron microscopy (AFM–TEM) sample holder. Many applications can be envisioned for these nanostructures ranging from nanothermometers to photo-protective storage and delivery devices.

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Wei, Cui Liu, Xiao Ping Zou, Jin Cheng, et al. "Carbon Nanotubes Grown by Ethanol Catalytic Combustion with an Additive of Thiophene." Advanced Materials Research 123-125 (August 2010): 627–30. http://dx.doi.org/10.4028/www.scientific.net/amr.123-125.627.

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Combustion method is a simple method to synthesize carbon nanotubes(CNTs), which employs flames of carbon-contained reactant to synthesize CNTs. It has been proved that combustion method is an effective method to synthesize carbon nanotubes and carbon nanofibers. In this paper, we reported the synthesis of CNTs by using ethanol catalytic combustion with an additive of thiophene, which employed ethanol as carbon source and fuel, nitrate as catalyst precursor, stainless steel as substrate, and thiophene as accelerant. Compared with previous reports on the synthesis of CNTs by ethanol catalytic combustion, great yield of CNTs were obtained with adding thiophene in ethanol. The reproducibility of the synthesis of CNTs in the case of adding thiophene in ethanol was greatly improved.

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Sementsov, Yu I., O. A. Cherniuk, S. V. Zhuravskyi, et al. "Synthesis and catalytic properties of nitrogen-containing carbon nanotubes." Himia, Fizika ta Tehnologia Poverhni 12, no. 2 (2021): 135–43. http://dx.doi.org/10.15407/hftp12.02.135.

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Nitrogen-containing carbon nanotubes (CNTs) were synthesized by the CVD method on oxide catalysts of Al-Fe-Mo-O by adding acetonitrile or ethylenediamine to the carbon source (propylene), or completely replacing it, as well as impregnating the original CNTs with urea, followed by heat treatment. The structure of nitrogen-containing CNTs (N-CNT) was characterized by the method of Raman scattering, transmission electron microscopy (TEM), differential thermal and gravimetric analysis (DTA, DTG) and X-ray photoelectron spectroscopy (XPS). The influence of the synthesis method on the number and chemical state of nitrogen heteroatoms in the structure of the carbon matrix is found. According to the TEM, nitrogen-containing CNTs have a characteristic bamboo-like structure, which is less perfect compared to the structure of the original CNTs: the characteristic Raman bands (G and D) are shifted to higher frequencies, their half-width and band D intensity increase relative to G. This is also manifested in the lower thermal stability of nitrogen-containing CNTs. According to the XPS, the direct synthesis of nitrogen-containing CNTs increases the total content of nitrogen atoms and the proportion of pyrrolic and quaternary nitrogen against the background of a significant decrease in the amount of pyridinic form. This can be explained by the fact that nitrogen is evenly distributed throughout the carbon matrix of CNTs, and during nitriding of CNTs with urea, nitrogen is included mainly in the surface layers and defects, because the pyridine form is characteristic of the edge location of the nitrogen atom in the graphene plane.The catalytic effect of multilayer nitrogen-containing carbon nanotubes (N-CNT) on the kinetics of decomposition of hydrogen peroxide in aqueous solutions at different pH values is considered. It is concluded that the method of direct synthesis of nitrogen-containing CNTs allows to obtain more catalytically active carbon nanotubes containing more nitrogen, mainly pyrrolic and quaternary type. It has been found that regardless of the method of synthesis, the maximum catalytic activity in the decomposition of hydrogen peroxide is observed at pH 7.

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Yamagiwa, Kiyofumi, Yuriko Iwao, Masafumi Mikami, Tsuneharu Takeuchi, Morihiro Saito, and Jun Kuwano. "Liquid-Phase Synthesis of Carbon Nanotubes from Alcohols." Key Engineering Materials 350 (October 2007): 19–22. http://dx.doi.org/10.4028/www.scientific.net/kem.350.19.

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Vertically aligned carbon nanotubes (CNTs) were grown on a stainless steel substrate (SUS304) by resistance-heating method in alcohols containing homogeneously dissolved cobaltocene Co(C5H5)2 as a catalyst source. Straight-chain primary alcohols, 1,2-ethanediol and cyclohexanol were used as carbon sources to examine the effects of the molecular structures on the morphology of the aligned CNTs. Methanol brought the best purity and alignment of CNTs of all the alcohols. The CNTs from 1,2-ethanediol was worse in the purity than those from ethanol with the same number of carbon atoms. The CNTs from cyclohexanol had a better purity than those from 1-hexanol. Distinctive features of this method are simple, low cost and a one-step process involving none of vacuum processes and catalyst preparation processes.

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Chitranshi, Megha, Anuptha Pujari, Vianessa Ng, et al. "Carbon Nanotube Sheet-Synthesis and Applications." Nanomaterials 10, no. 10 (2020): 2023. http://dx.doi.org/10.3390/nano10102023.

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Decades of extensive research have matured the development of carbon nanotubes (CNTs). Still, the properties of macroscale assemblages, such as sheets of carbon nanotubes, are not good enough to satisfy many applications. This paper gives an overview of different approaches to synthesize CNTs and then focuses on the floating catalyst method to form CNT sheets. A method is also described in this paper to modify the properties of macroscale carbon nanotube sheets produced by the floating catalyst method. The CNT sheet is modified to form a carbon nanotube hybrid (CNTH) sheet by incorporating metal, ceramic, or other types of nanoparticles into the high-temperature synthesis process to improve and customize the properties of the traditional nanotube sheet. This paper also discusses manufacturing obstacles and the possible commercial applications of the CNT sheet and CNTH sheet. Manufacturing problems include the difficulty of injecting dry nanoparticles uniformly, increasing the output of the process to reduce cost, and safely handling the hydrogen gas generated in the process. Applications for CNT sheet include air and water filtering, energy storage applications, and compositing CNTH sheets to produce apparel with anti-microbial properties to protect the population from infectious diseases. The paper also provides an outlook towards large scale commercialization of CNT material.

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Cao, Anyuan, Xianfeng Zhang, Cailu Xu, Ji Liang, Dehai Wu, and Bingqing Wei. "Aligned carbon nanotube growth under oxidative ambient." Journal of Materials Research 16, no. 11 (2001): 3107–10. http://dx.doi.org/10.1557/jmr.2001.0428.

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Carbon nanotubes (CNTs) are always produced under a reductive ambient with hydrogen present using the chemical vapor deposition method. Oxidative media, such as carbon dioxide and oxygen, could damage the tubular structures by opening the nanotube ends or etching the tube walls. Here we report the synthesis of aligned defective, but clean, CNTs in the presence of water vapor. The tube walls were found broken as well as the tube ends. CNTs with a large amount of exposed broken sites on their tube walls have potential applications in many areas such as energy storage.

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Cui, Ruixue, Lujun Pan, He Ma, Peng Wang, and Muhammad Asif. "Highly efficient synthesis of carbon nanocoils on alumina spheres." RSC Advances 6, no. 36 (2016): 30125–29. http://dx.doi.org/10.1039/c6ra01055e.

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Carbon nanocoils (CNCs) and carbon nanotubes (CNTs) can be selectively synthesized on the surfaces of alumina spheres using an Fe2(SO4)3/SnCl2 catalyst with different molar ratios of Fe to Sn by a thermal chemical vapor deposition method.

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Ding, Zhao Yong, Bao Min Sun, Bing Hao Xu, Yuan Chao Liu, and Yong Hong Guo. "Catalyst Synthesis of Carbon Nanotubes by Substrate Method." Advanced Materials Research 129-131 (August 2010): 1331–35. http://dx.doi.org/10.4028/www.scientific.net/amr.129-131.1331.

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Pyramid shaped pyrolysis flame is a new method for carbon nanotubes (CNTs) synthesis. Oxy-acetylene flame was used as the source of heat, CO as the source of carbon, iron pentacarbonyl (Fe(CO)5) as the source of catalyst precursor. Field emission scanning electron microscope(FE-SEM), High resolution transmission electron microscopy (HR-TEM) and Raman spectra were used to illustrate the results of experimental. In this experimental, coating substrate is not a special process, but a part of sampling. In the first 60s of sampling time, there were not CNTs synthesis, only the phase that substrate coats particles and temperature rise, so in this phase, catalyst particles formed. 304 stainless steel plate, monocrystalline silicon chip, and brass plate were used as substrates to synthesize CNTs. 304 stainless steel plate could gain straight, long, and uniform CNTs, monocrystalline silicon chip gain curly and short CNTS, while brass gain nothing but particles. Although single-walled carbon nanotubes (SWNTs) were not observed by SEM and TEM, it was successfully done by Raman spectra, in spite of the yield was small.

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Zhang, Yafei, Mikka N.-Gamo, Kiyoharu Nakagawa, and Toshihiro Ando. "Synthesis of aligned carbon nanotubes in organic liquids." Journal of Materials Research 17, no. 9 (2002): 2457–64. http://dx.doi.org/10.1557/jmr.2002.0358.

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A simple and novel method was developed for efficient synthesis of aligned multiwalled carbon nanotubes (CNTs) in methanol and ethanol under normal pressure. The CNTs' alignment and structures were investigated using Raman scattering and x-ray diffraction spectroscopy. A unique kind of coupled CNT was synthesized in which one rotated to the left and one rotated to the right. Chains periodically bridged the coupled CNTs. The growth mechanism of the CNTs within organic liquid is proposed to be a catalytic process at the Fe film surface in a dynamic and thermal nonequilibrium condition in organic liquids.

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Fatiha, Ismail, Aziah Buang Nor, and Muhammad Zamir Othman. "Role of Carbon Source in the Synthesis of Carbon Nanotubes via Catalytic Chemical Vapour Deposition." Advanced Materials Research 364 (October 2011): 16–19. http://dx.doi.org/10.4028/www.scientific.net/amr.364.16.

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Development of technology in synthesizing a novel nanoscale material has been the main concern in the current material science. This study investigates the effect of two different carbon sources on the formation of carbon nanotubes (CNTs) via catalytic chemical vapour deposition (CCVD) method. Two types of carbon source i.e. acetylene gas and ethanol liquid were used for the synthesis of CNTs. The catalysts used in the synthesis of CNTs were formulated from nickel (Ni), copper (Cu) and praseodymium (Pr) using the wet impregnation method. The as-synthesized CNTs obtained were characterized using field emission-scanning electron microscope (FE-SEM), Thermal gravimetric analysis (TGA) and transmission electron microscope (TEM). The analysis result confirmed that the prepared catalysts were active for the production of CNTs. TEM analysis revealed that different morphologies of CNTs were formed when different carbon source was used. FE-SEM micrographs confirmed that acetylene proficient in producing multi walled carbon nanotubes (MWCNTs) and ethanol in producing heterojunctions CNTs with diameter range of 60 to 120 nm and 10 to 40 nm, respectively. Meanwhile, TGA analysis revealed thermal stability of each type of CNTs at different temperature of decomposition. Generally, this research has successful produced different types of CNTs when different carbon source is used.

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Nurulhuda, I., R. Poh, M. Z. Mazatulikhma, and Mohamad Rusop. "Evaporated Ethanol as Precursor for Carbon Nanotubes Synthesis." Advanced Materials Research 832 (November 2013): 322–27. http://dx.doi.org/10.4028/www.scientific.net/amr.832.322.

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Single-walled carbon nanotubes (SWCNT) were synthesized by using a simple evaporating method and a double furnace system. Ethanol was chosen as a carbon precursor because it has an evaporating temperature of 78 °C and was reported to produce a high purity of CNTs. Evaporated ethanol can be used as a precursor for carbon nanotubes (CNTs) synthesis. Ethanol was evaporated at 80 °C and channeled directly into a double furnace system. Furnace 1 was maintained at 180 °C and furnace 2 was set at 700 °C, 800 °C and 900 °C. The CNTs were then characterized by thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM) and Raman spectroscopy. Helical CNTs were observed at 700°C, webs of hollow tubes at 800 °C, and long tube structures at 900 °C based on FESEM. The diameter of CNTs that were synthesized ranged between 54 - 200 nm. Raman spectrum revealed that the G-band was 1590 cm-1 and the D-band was about 1350 cm-1. SWCNT was determined by RBM (radial breathing mode) to be between 200 - 300 raman shifts (cm-1). The modified CVD (chemical vapor deposition) system set up in the present study is successfully used for large scale synthesis of CNTs from an aqueous precursor such as ethanol.

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ETMAN, MOHAMED A., R. M. RASHAD, and M. K. BEDEWY. "SYNTHESIS AND CHARACTERIZATION OF CARBON NANOTUBES REINFORCED POLYMER NANOCOMPOSITES." International Journal of Nanoscience 08, no. 03 (2009): 237–42. http://dx.doi.org/10.1142/s0219581x09006225.

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An experimental program was designed to synthesize and characterize carbon nanotubes (CNTs) and CNTs reinforced polymeric matrix nanocomposites. PMMA, and PS, matrices were adopted for this investigation using different percents of CNTs loading of 0, 1, 3, and 5 and wt%. Morphological characterization was carried out using SEM, TEM, and TEDM microscopy. Mechanical properties were also measured to evaluate the enhancement effect of the CNTs loading percent. The results revealed a remarkable enhancement of the strength and ductility of the matrix material at 3 wt% of reasonably dispersed CNTs.

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Kure, N., M. N. Hamidon, S. Azhari, et al. "Simple Microwave-Assisted Synthesis of Carbon Nanotubes Using Polyethylene as Carbon Precursor." Journal of Nanomaterials 2017 (2017): 1–4. http://dx.doi.org/10.1155/2017/2474267.

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In this work, a quick and effective method to synthesize carbon nanotubes (CNTs) is reported; a commercial microwave oven of 600 W at 2.45 GHz was utilized to synthesize CNTs from plasma catalytic decomposition of polyethylene. Polyethylene and silicon substrate coated with iron (III) nitrate were placed in the reaction chamber to form the synthesis stock. The CNTs were synthesized at 750°C under atmospheric pressure of 0.81 mbar. Raman spectroscopy and field emission scanning electron microscope revealed the quality and entangled bundles of mixed CNTs from which the diameters of the CNTs were calculated to be between 1.03 and 25.00 nm. High resolution transmission electron microscope further showed that the CNTs obtained by this method are graphitized. Energy dispersive X-ray analysis and thermogravimetric analysis revealed above 98% carbon purity.

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Dikio, Ezekiel D., Albert J. Kupeta, and Force T. Thema. "A Comparative Study of the Effect of MgO and CaCO3as Support Materials in the Synthesis of Carbon Nanotubes with Fe/Co as Catalyst." Journal of Chemistry 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/641823.

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A comparative study of the effect of magnesium oxide and calcium carbonate as support material in the synthesis of carbon nanotubes using the catalyst Fe/Co is presented. The synthesized carbon nanotubes were characterized with Raman spectroscopy, scanning electron spectroscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction spectroscopy (XRD), and energy dispersive spectroscopy (EDS). The morphology of the carbon nanotubes synthesized with magnesium oxide as support material gives rise to carbon nanotubes with consistent and well-defined structure unlike that synthesized with calcium carbonate. TheID/IGratio of synthesized carbon nanotubes (CNTs) was 0.8544 for magnesium oxide supported compared to 0.8501 for calcium carbonate supported carbon nanotube.

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Tanemura, Masaki, R. Koyanagi, T. Nagumo, M. Kitazawa, Lei Miao, and Sakae Tanemura. "Synthesis of Carbon Nanotubes Using Hydrocarbon Ion Beams." Advanced Materials Research 11-12 (February 2006): 547–50. http://dx.doi.org/10.4028/www.scientific.net/amr.11-12.547.

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Toward the tailored growth of carbon nanotubes (CNTs), CNT growth using hydrocarbon ion beams at the ion energy of 150 eV and the ion current densities of 10 ∼ 165 μA/cm2 was challenged at various growth temperatures. Fibrous protrusions with an amorphous nature grew at a low ion current density, whereas highly crystallized multi-wall CNTs were synthesized at high ion current densities. The higher the growth temperature and the ion current density, the smaller the CNT diameter. Similar to the conventional PECVD-grown CNTs, they grew via the so-called “tip-growth mode.”

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Sun, Zhen Feng, Le Hua Qi, Qiao Juan Gong, and Yang Shu. "The Effect of Carbon Substrates on In Situ Synthesis Carbon Nanotube and Carbon Nanospheres by CVD Process." Advanced Materials Research 335-336 (September 2011): 293–96. http://dx.doi.org/10.4028/www.scientific.net/amr.335-336.293.

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The morphology and growth mechanism of carbon nanotubes(CNTs) and carbon nanospheres (CNSs) produced by in-situ CVD method on different substrates were investigated using scanning electron microscopy (SEM), transmission electron microscope (TEM) and energy dispersive spectrometer (EDS) technology. The experimental results show that the growth of carbon-nano-material has great substrate independence during in-situ CVD process. At the same reaction conditions, CNTs with diameters of 60-140nm and CNSs with diameters of 150-450nm were synthesized on the 1K carbon cloth and graphite paper substrate, respectively. Based on the experimental results, a probable growth mechanism was presented for different carbon substrates. The explanation for the formation process is the difference of the concentration gradient and growth rate in the catalyst.

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Pillai, Sreejarani K., Suprakas Sinha Ray, and Mathew Moodley. "Purification of Multi-Walled Carbon Nanotubes." Journal of Nanoscience and Nanotechnology 8, no. 12 (2008): 6187–207. http://dx.doi.org/10.1166/jnn.2008.345.

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The discovery of carbon nanotubes (CNTs) has stimulated intensive research to characterize their structure and to determine their physical properties, both by direct measurement and through predictive methods. Many of the fundamental and remarkable properties of CNTs are now well-known, and their exploitation in a wide range of applications forms a large part of research currently in progress. However, the absence of a reliable, large-volume production capacity, simple and efficient purification methods, the high cost of carbon nanotubes and the fact that there is little selectivity in controlling the properties of the product are factors that have principally inhibited the commercialization of CNT technologies. Ever since CNTs were detected, considerable efforts have been directed at their synthesis, characterization and functionalization. Nevertheless, the CNT sample obtained by different techniques has the disadvantage of containing non-CNT impurities, such as graphitic particles, fullerenes, residual catalyst particles and amorphous carbon, which degrade the intrinsic properties of these materials. If the carbon nanotube is ever to accomplish its promise as an industrial material, large and high-quality aliquots, will be required. A number of purification methods involving elimination processes, such as physical separation, gas-phase and liquid-phase oxidation, in combination with chemical treatments, have been developed for nanotube materials. Though the quantitative determination of purity remains controversial, reported yields are best regarded with an appropriate level of scepticism on the method of assay. This review highlights the past and recent developments in the purification of multi-walled carbon nanotubes.

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Chen, Tao, and Aigen Li. "Synthesizing carbon nanotubes in space." Astronomy & Astrophysics 631 (October 18, 2019): A54. http://dx.doi.org/10.1051/0004-6361/201935789.

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Context. As the fourth most abundant element in the universe, carbon (C) is widespread in the interstellar medium (ISM) in various allotropic forms (e.g. fullerenes have been identified unambiguously in many astronomical environments, the presence of polycyclic aromatic hydrocarbon molecules in space has been commonly acknowledged, and presolar graphite, as well as nanodiamonds, have been identified in meteorites). As stable allotropes of these species, whether carbon nanotubes (CNTs) and their hydrogenated counterparts are also present in the ISM or not is unknown. Aims. The aim of the present works is to explore the possible routes for the formation of CNTs in the ISM and calculate their fingerprint vibrational spectral features in the infrared (IR). Methods. We studied the hydrogen-abstraction and acetylene-addition (HACA) mechanism and investigated the synthesis of nanotubes using density functional theory (DFT). The IR vibrational spectra of CNTs and hydrogenated nanotubes (HNTs), as well as their cations, were obtained with DFT. Results. We find that CNTs could be synthesized in space through a feasible formation pathway. CNTs and cationic CNTs, as well as their hydrogenated counterparts, exhibit intense vibrational transitions in the IR. Their possible presence in the ISM could be investigated by comparing the calculated vibrational spectra with astronomical observations made by the Infrared Space Observatory, Spitzer Space Telescope, and particularly the upcoming James Webb Space Telescope.

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Zhao, Chen, Zhejuan Zhang, Jun Guo, Qiang Hu, Zhuo Sun, and Xianqing Piao. "Controllable Synthesis of Special Reed-Leaf-Like Carbon Nanostructures Using Copper Containing Catalytic Pyrolysis for High-Performance Field Emission." Applied Sciences 9, no. 3 (2019): 440. http://dx.doi.org/10.3390/app9030440.

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Special reed-leaf-like carbon nanostructures have been realized by using chemical vapor deposition (CVD) under the combined action of copper containing catalytic pyrolysis and ammonia (NH3) gas. The nucleation and growth mechanisms of CNLs based on growth parameters are discussed. The Raman spectra of carbon nanotubes (CNTs), CNLs and CNT-CNL composites were measured and found to be strongly influenced by the type of gas. Field emission (FE) properties of CNL-CNT composites were observed with a lower turn-on electric field of 0.73 V/µm, and a higher current density of 18.0 mA/cm2 at an electric field of 2.65 V/µm, which are superior to those of CNTs and flower-like CNLs. This is because there are more field emitters in CNLs inter-planted in CNTs. We consider that the unique FE stability of CNTs and defects in CNLs play a synergetic role on the improved FE properties.

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MUKHOPADHYAY, KINGSUK, and GYANESH NARAYAN MATHUR. "SYNTHESIS OF 2D QUASI-ALIGNED MULTIWALLED CARBON NANOTUBES BY CATALYTIC CHEMICAL VAPOR DEPOSITION METHOD." International Journal of Nanoscience 02, no. 03 (2003): 153–64. http://dx.doi.org/10.1142/s0219581x03001152.

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Alignment or patterning of carbon nanotubes (CNTs) is particularly important for fabricating functional devices such as field emitters, nanophotonics, nanoelectronics, and ultrahydrophobic materials. This work reports on the synthesis of 2D quasi-aligned carbon nanotube bundles by catalytic chemical vapor deposition (CCVD) method using a series of catalysts and a study of their performance in a nutshell.

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Liu, Dan, Jie Zhu, Sameera Ivaturi, et al. "Giant magnetic coercivity in Fe3C-filled carbon nanotubes." RSC Advances 8, no. 25 (2018): 13820–25. http://dx.doi.org/10.1039/c7ra13671d.

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One of the major challenges in the synthesis of ferromagnetically filled carbon nanotubes (CNTs) is the achievement of high coercivities. Here we report an anomalously high coercivity observed in Fe3C filled CNTs.

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Liu, Guangli, Bin Zhou, Jinwei Liu, and Huazhang Zhao. "The Bionic Water Channel of Ultra-Short, High Affinity Carbon Nanotubes with High Water Permeability and Proton Selectivity." Sustainability 13, no. 1 (2020): 102. http://dx.doi.org/10.3390/su13010102.

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The development of the bionic water channel aims to replace the possible use of natural aquaporins (AQPs) for water purification, while retaining the ability of natural AQPs to carry out ultra-fast water transport and repel ions. Carbon nanotube channels (CNTCs) are a convenient membrane-based model system for studying nano-fluidic transport that replicates a number of key structural features of biological membrane channels. In this report, we describe protocols for CNTCs synthesis by ultrasound-assisted cutting of long CNTs in the presence of lipid amphiphiles. CNTCs have a similar thickness to the lipid membrane and high affinity for it. The ultra-short high-affinity CNTCs have high permeability and ion selectivity. The water permeability of the CNTCs is 1936 ± 123 μm/s, which is 2.3 times that of natural AQPs, and completely rejects salt ions. In general, carbon nanotubes represent a multifunctional nanopore building module for creating high-ranking functional bionic materials. This study has reference significance for the design of new bionic water channel and the actual development of bionic membrane based on CNTs.

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Lin, Chuen-Chang, and Yi-Wei Lin. "Synthesis of Carbon Nanotube/Graphene Composites by One-Step Chemical Vapor Deposition for Electrodes of Electrochemical Capacitors." Journal of Nanomaterials 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/741928.

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To control the packing density of carbon nanotubes (CNTs) and the number of graphene layers, carbon nanotube/graphene composites are directly grown on cobalt (Co) catalysts-coated nickel foam by one-step ambient pressure chemical vapor deposition (CVD) at different temperatures and times. The carbon nanotube/graphene composites grown by one-step CVD at 850°C for 10 min possess the highest specific capacitance. Furthermore, a lower growing temperature leads to a higher packing density of CNTs and a smaller number of layers of graphene. A shorter growing time also leads to a smaller number of layers of graphene.

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Wojtera, Katarzyna, Malgorzata Walczak, Lukasz Pietrzak, Justyna Fraczyk, Lukasz Szymanski, and Anna Sobczyk-Guzenda. "Synthesis of functionalized carbon nanotubes for fluorescent biosensors." Nanotechnology Reviews 9, no. 1 (2020): 1237–44. http://dx.doi.org/10.1515/ntrev-2020-0096.

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AbstractDespite the development of pharmacy, there are still incurable diseases for which the medicine has not been found yet. Because many diseases are asymptomatic in their first stage of development, often early detection is the crucial factor in combating them. The article describes the process of synthesis of carbon nanotubes (CNTs) which can be useful in medical diagnostics. CNTs were synthesized by chemical vapor deposition. The obtained material was subjected to functionalization – attaching fluorescent markers. In order to check the usefulness of the obtained structures in diagnostics, their fluorescent properties were examined. The results of fourier transform infrared spectroscopy thermogravimetric analysis and scanning electron microscopy prove that, after proper functionalization, CNTs could be used as fluorescents markers.

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Zhou, Yongsheng, Pan Jin, Yatong Zhou, and Yingchun Zhu. "Carbon nanospheres hanging on carbon nanotubes: a hierarchical three-dimensional carbon nanostructure for high-performance supercapacitors." Journal of Materials Chemistry A 5, no. 32 (2017): 16595–99. http://dx.doi.org/10.1039/c7ta05512a.

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Allaedini, Ghazaleh, Payam Aminayi, and Siti Masrinda Tasirin. "The Effect of Alumina and Magnesia Supported Germanium Nanoparticles on the Growth of Carbon Nanotubes in the Chemical Vapor Deposition Method." Journal of Nanomaterials 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/961231.

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The effect of alumina and magnesia supported germanium (Ge) nanoparticles on the synthesis of carbon nanotubes (CNTs) using the chemical vapor deposition (CVD) method in atmospheric pressure was investigated. The TEM micrographs confirmed the formation of carbon nanotubes, and the field emission scanning electron microscopy (FESEM) analysis suggested a tip-growth mechanism for the grown carbon nanotubes. The X-ray diffraction (XRD) pattern indicated a graphitic nature of the carbon nanotubes. The obtained CNTs using Ge nanoparticles supported by MgO resulted in a higher degree of graphitization than the CNTs obtained using Ge nanoparticles supported by Al2O3. Raman spectroscopy analysis of the CNTs confirmed the presence of radial breathing modes (RBM), which verified the formation of CNTs. High frequency Raman analysis demonstrated that the degree of graphitization of the synthesized CNTs using magnesia supported Ge nanoparticles is higher than that of the alumina supported Ge nanoparticles with the values of (ID/IG) ratios equal to 0.45 and 0.73, respectively.

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Chung, Uoo Chang, Deok Bo Lee, Y. U. Jeong, M. J. Ha, and Won Sub Chung. "Effect of H₂ Gas on Carbon Nanotubes Synthesis." Materials Science Forum 475-479 (January 2005): 3559–62. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.3559.

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The effect of H2 gas during the carbon nanotubes (CNTs) synthesis with CO-H2 gas mixture was investigated using by mass measurement, and scanning electron microscopy (SEM). The maximum weight and yield of the synthesized carbon (C) were obtained when the mixture ratio of H2:CO was 3:7 and 9:1, respectively. In case of 100% carbon monoxide (CO) without hydrogen (H2) addition, the weight of carbon increased, but CNTs were not observed. The CNTs were formed when the contents of H2 reaches at least 10%, and their structures became more distinct with an increase of H2 addition, and then the shapes of CNTs were more thin and straight. When the contents of H2 was 80% (H2:CO = 8:2), the shapes and growth of CNTs showed an optimal condition. On the other hand, when the contents of H2 was higher than the critical value, the shapes of CNTs became worse due to transition into inactive surface of catalyst. It was found that H2 played a major role in the shapes and structures of CNTs.

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Mohamad, Imran Syakir, S. Thiru Chitrambalam, Sharifah Bee Abdul Hamid, W. M. Chin, K. H. Yau, and Idral Febrian. "A Comparison Study on the Heat Transfer Behavior of Aqueous Suspensions of Rod Shaped Carbon Nanotubes with Commercial Carbon Nanotubes." Advanced Materials Research 667 (March 2013): 35–42. http://dx.doi.org/10.4028/www.scientific.net/amr.667.35.

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Carbon nanotubes (CNTs) are said to be among the most potential materials in applications of nanodevices, nanocomposites and nanostructure due to their excellent mechanical and physical attributes. CNTs were first discovered by S. Iijima in 1991 where he has reported in his article the synthesis of needle-like tubes by using an arc-discharge evaporation. After the immense discovery, the number of research on CNTs has increased significantly, focusing on their mechanical characteristics, dynamics properties and applications in nanotechnology. This paper attempts to present a review of a quite number of publications on CNTs and their dynamic properties. The main topics covered in this review are the applications of CNTs, their dynamic characteristics including the modeling and simulation of vibrating CNTs, and finally the vibration modes of CNTs.

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Noor Safitri, Rika, Suriani Abu Bakar, Suhufa Alfarisa, et al. "Zinc Oxide/Carbon Nanotubes Nanocomposite: Synthesis Methods and Potential Applications." Advanced Materials Research 1109 (June 2015): 45–49. http://dx.doi.org/10.4028/www.scientific.net/amr.1109.45.

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Zinc oxide/carbon nanotubes (ZnO/CNTs) nanocomposite has been widely studied in the last few years due to their remarkable properties and versatile applications. Various methods have been presented in order to enhance the excellent properties of ZnO/CNTs nanocomposite. Here we reviewed several synthesis methods including single- and multiple steps to fabricate the ZnO/CNTs nanocomposite and the potential application of the nanocomposite in field emission and solar cell devices.

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Patil, K. N., and Chetan S. Solanki. "Precursor to High Purity Carbon Nanotubes: A Step by Step Evaluation of Carbon Yield." Journal of Nano Research 6 (June 2009): 75–87. http://dx.doi.org/10.4028/www.scientific.net/jnanor.6.75.

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Yield of carbon nanotubes (CNTs) depends on numerous process parameters such as temperature of synthesis, type of catalyst, type of precursor, time of precursor flow and partial pressure of precursor gas as well as carrier gas, etc. Experiments were performed in order to find the optimum temperature of synthesis for varying time of precursor flow. The yield was evaluated in terms of mass of crystalline CNTs per gram of substrate and/or catalyst. The CNTs were grown on a calcium carbonate (CaCO3) substrate, with iron-cobalt (Fe-Co) as a catalyst, using acetylene (C2H2) as a precursor gas and argon (Ar) as a carrier gas. A three-stage purification process, incorporating two acid treatment steps and one annealing step, was used for purification which ensures high grade purity of CNTs. The highest yield of 21.4 g of CNTs per g of catalyst was achieved at 700oC for 60 min of synthesis. The CNTs were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Raman, Thermo-gravimetric analysis (TGA), and Gas chromatography (GC).

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Xiao, Ying, Zubair Ahmed, Zichao Ma, Changjian Zhou, Lining Zhang, and Mansun Chan. "Low Temperature Synthesis of High-Density Carbon Nanotubes on Insulating Substrate." Nanomaterials 9, no. 3 (2019): 473. http://dx.doi.org/10.3390/nano9030473.

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A method to synthesize high-density, vertically-aligned, multi-wall carbon nanotubes (MWCNTs) on an insulating substrate at low temperature using a complementary metal–oxide–semiconductor (CMOS) compatible process is presented. Two factors are identified to be important in the carbon nanotube (CNT) growth, which are the catalyst design and the substrate material. By using a Ni–Al–Ni multilayer catalyst film and a ZrO2 substrate, vertically-aligned CNTs can be synthesized at 340 °C using plasma-enhanced chemical vapor deposition (PECVD). Both the quality and density of the CNTs can be enhanced by increasing the synthesis temperature. The function of the aluminum interlayer in reducing the activation energy of the CNT formation is studied. The nanoparticle sintering and quick accumulation of amorphous carbon covering the catalyst can prematurely stop CNT synthesis. Both effects can be suppressed by using a substrate with a high surface energy such as ZrO2.

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Zhang, Zhi, Shichun Mu, Bowei Zhang, et al. "A novel synthesis of carbon nanotubes directly from an indecomposable solid carbon source for electrochemical applications." Journal of Materials Chemistry A 4, no. 6 (2016): 2137–46. http://dx.doi.org/10.1039/c5ta09631f.

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Carbon nanotubes (CNTs) are firstly synthesized through a novel low cost self-vaporized chemical vapor deposition (SCVD) technique, which represents a novel approach toward large scale production of CNTs.

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Monthioux, M., E. Flahaut, and J.-P. Cleuziou. "Hybrid carbon nanotubes: Strategy, progress, and perspectives." Journal of Materials Research 21, no. 11 (2006): 2774–93. http://dx.doi.org/10.1557/jmr.2006.0366.

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We introduce the concept of meta-nanotubes, among which are hybrid carbon nanotubes (X@CNTs), which are CNTs whose hollow core is filled—fully or partially—with foreign atoms, molecules, or compounds. The article focuses on the latter, describing their potential interest and the various ways currently available to synthesize them, while providing examples of the resulting materials mainly taken from the author’s works but also from literature, as characterized by means of high-resolution microscopy and related techniques. We discuss advantages and drawbacks of the various synthesis routes to help willing scientists and engineers to define a strategy for X@CNT synthesis with respect to their specific goals and expectations. Some examples of peculiar properties and behaviors of X@CNTs will be provided as well, although such related investigations are still scarcely reported because we are dealing with quite new nanomaterials.

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Nguyen, Van Hoa, and Jae-Jin Shim. "Green Synthesis and Characterization of Carbon Nanotubes/Polyaniline Nanocomposites." Journal of Spectroscopy 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/297804.

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Carbon nanotubes/polyaniline (CNT/PANI) nanocomposites were synthesized by the interfacial polymerization of aniline in the presence of CNTs using two green solvents, water and an ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF4]), as the two phases. The formation and incorporation of PANI on the surface of the CNTs were confirmed by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy ultraviolet-visible spectroscopy, and X-ray photoelectron spectroscopy. The analyses showed that the surface of the CNTs was coated with different morphologies of thin PANI layers depending on whether a HCl or HNO3solution was used. The thermal stability of the composites was much better than that of the bare CNTs and pure PANI. The as-prepared composites were also used to modify the nickel foam electrodes for characterization of the electrochemical properties.

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Patel, Dinesh K., Hye-Been Kim, Sayan Deb Dutta, Keya Ganguly, and Ki-Taek Lim. "Carbon Nanotubes-Based Nanomaterials and Their Agricultural and Biotechnological Applications." Materials 13, no. 7 (2020): 1679. http://dx.doi.org/10.3390/ma13071679.

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Carbon nanotubes (CNTs) are considered a promising nanomaterial for diverse applications owing to their attractive physicochemical properties such as high surface area, superior mechanical and thermal strength, electrochemical activity, and so on. Different techniques like arc discharge, laser vaporization, chemical vapor deposition (CVD), and vapor phase growth are explored for the synthesis of CNTs. Each technique has advantages and disadvantages. The physicochemical properties of the synthesized CNTs are profoundly affected by the techniques used in the synthesis process. Here, we briefly described the standard methods applied in the synthesis of CNTs and their use in the agricultural and biotechnological fields. Notably, better seed germination or plant growth was noted in the presence of CNTs than the control. However, the exact mechanism of action is still unclear. Significant improvements in the electrochemical performances have been observed in CNTs-doped electrodes than those of pure. CNTs or their derivatives are also utilized in wastewater treatment. The high surface area and the presence of different functional groups in the functionalized CNTs facilitate the better adsorption of toxic metal ions or other chemical moieties. CNTs or their derivatives can be applied for the storage of hydrogen as an energy source. It has been observed that the temperature widely influences the hydrogen storage ability of CNTs. This review paper highlighted some recent development on electrochemical platforms over single-walled CNTs (SWCNTs), multi-walled CNTs (MWCNTs), and nanocomposites as a promising biomaterial in the field of agriculture and biotechnology. It is possible to tune the properties of carbon-based nanomaterials by functionalization of their structure to use as an engineering toolkit for different applications, including agricultural and biotechnological fields.

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Toyota, Hiromichi, Ken Nagaoka, Xia Zhu, et al. "Synthesis of Single-Wall Carbon Nanotubes by In-Liquid CVD." Key Engineering Materials 749 (August 2017): 217–22. http://dx.doi.org/10.4028/www.scientific.net/kem.749.217.

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High-speed synthesis of the carbon nanotubes in liquid is introduced. The conventional method for synthesizing carbon nanotubes is generally known as gas-phase chemical-vapor deposition (CVD). With that method, carbon nanotubes of high purity can be synthesized, but the synthesis rate is low. Even though the synthesized carbon nanotubes are excellent materials, they cannot be used in large quantities. Accordingly, in this study, single-wall carbon nanotubes (SWCNTs) are synthesized by “in-liquid” CVD. Since the molecular density of a liquid is much higher than that of a gas and the liquid has a cooling effect, performing CVD in a liquid can provide a high-speed growth rate of CNTs on substrate materials. A silicon substrate on which cobalt micro particles are deposited as the catalyst was used. Electrical-resistance heating was used for growing carbon nanotubes in pure ethanol. The synthesized nanotubes were analyzed by scanning electron microscope, transmission electron microscope, and Raman spectroscopy. The results of these analyses indicate that SWCNTs were successfully synthesized over a wide area of the substrate surface. By investigating the synthesized carbon nanotubes under varied experimental conditions (such as pressure and substrate surface roughness), it is shown that surface roughness of the substrate and the bubble behavior are related to the synthesis mechanism of the CNTs.

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Journal articles on the topic 'Synthesis of carbon nanotubes (CNTs)'

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