Abstract Synthesis of carbon nanotubes at low temperatures as low as 540oC was demonstrated via floating catalyst chemical vapor deposition method. Catalytic decomposition of benzene was employed using ferrocene as a catalyst precursor. In this work, the issue of introducing catalyst particles into the reactor has been developed by using single heating source for both the catalyst and reactor. In-situ monitoring device was used to observe the temperature profile in the reactor and thus, to initiate the reaction. CNTs with both types (aligned and entangled) were synthesized with diameter distribution ranging from 10 to 40 nm. This new technique would contribute with the synthesis of carbon nanotubes for microelectronic applications since it offers relatively low synthesis temperature.
Introduction:
Since their first discovery in 1991 (Iijima, 1991), carbon nanotubes attracted much attention due to nanoscale dimensions and promising shape as well as their potential properties. Many methods for the synthesis of CNTs have been used and developed (Ajayan, 1992; Ishigami et al., 2000; Lee et al., 2002). Among all synthesis methods, chemical vapor deposition (CVD) is widely used to due to its efficient cost and low operating temperatures required (Shyu et al.,2001; Han et al., 2003; Ni et al., 2006). Depending on the way of introducing the metal catalyst into the reactor, the CVD method can be conducted via supporting catalyst or floating catalyst technique. Floating catalyst method (FC-CVD) has gained much popularity due to its simplicity and the purification step is not required to recover CNTs from the substrate. In addition, direct product collection from the effluent and the absence of support material further reduce the amount ...
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...n, J. (2002). Large-scale synthesis of carbon nanotubes by plasma rotating arc discharge technique
Lee, Y., Kim, N., Park, J., Han, J., Choi, Y., Ryu, H., Lee, H. (2003). Temperature-dependent growth of carbon nanotubes by pyrolysis of ferrocene and acetylene in the range between 700°C and 1000°C. Chemical Physics Letters, 372, 853-859.
Liao, K., Ting, J. (2006). Characteristics of aligned carbon nanotubes synthesized usin a high-rate low-temperature process. Diamond and Related Materials, 2006, 1210-1216.
Ni, L., Kuroda, K., Zhou, L., Kizuka, T., Ohta, K., Matsuishi, K., Nakamura, J. (2006). Kinetic study of carbon nanotube synthesis over Mo/Co/MgO catalysts. Carbon, 44, 2265-2272.
Shyu, Y., Hong, F. (2001). Low-temperature growth and field emission of aligned carbon nanotubes by chemical vapor deposition. Materials Chemistry and Physics, 72, 223-227.
Thermal methods of analysis have been in use for quite a long time. Their application in the analysis of pharmaceutical materials has made it possible for pharmacists and researchers to understand their contents and characteristics. However, thermal methods have several disadvantages that have led researchers to opt for nano-thermal methods of analysis. Nano-thermal analysis methods use special resolution imaging potential that is enhanced by the availability of atomic force microscopy and thermal analysis methods.
The small size ranging from 0.1 to 10 micrometres of nanobots make it difficult to be constructed. The process of working atom by atom and molecule by molecule is monotonous work and the miniaturization of synthetic mechanisms to a nanoscale will only be achievable with the advancement of research in metallurgy.
In terms of kinetics, specifically speaking, the rate of reaction as determined by the concentration, reaction orders, and rate constant with each species in a chemical reaction. By using the concentration of the catalyst and the temperature, the overall reaction rate was determined. The rate constants of K0, Kobs, and Kcat can be derived via the plotting of the absorption at 400nm of p-nitrophenol vs. the concentration of the catalyst imidazole. Lastly, the free energy of activation, G, that is necessary to force the reactant’s transformation of the reactant to the transition state structure will be determined by using the equation G = H – TS derived from the Eyring plot. Introduction: The purpose of the experiment is to study the rate of reaction through varying concentrations of a catalyst or temperatures with a constant pH, and through the data obtained the rate law, constants, and activation energies can be experimentally determined.
Due to the varied properties and the scope of application which the CNTs possess, it is of paramount importance that CNTs are produced sufficiently at a competitive cost with the existing technology. The research over two decades, since the discovery of CNTs at Iijima’s Laboratory in 1991, has not helped in reduction of cost or production of CNTs of well-defined properties on a massive scale (Kumar, n.d.). This is mainly because of the complexity in the growth mechanism of CNTs. Extra ordinary properties and applications cannot be unleashed without the fundamental understanding of the growth mechanism of Carbon Nanotubes (Kumar, n.d.). There are several methods to produce Carbon Nanotubes in a laboratory setup. Some of widely used techniques include
Michael P. Broadribb, C. (2006). Institution of Chemical Engineers . Retrieved July 26, 2010, from IChemE: http://cms.icheme.org/mainwebsite/resources/document/lpb192pg003.pdf
To investigate the temperature change in a displacement reaction between Copper Sulphate Solution and Zinc Powder
In order to gain strong insight into the surface chemistry of silica we have perform a thorough literature search. Our goal is to identify the pioneer research performed on silica and silica supported catalyst. Particular interest lies in silica-water-cobalt and silica-alcohol-cobalt systems. This study is both on macro and micro level so that a complete theoretical base can be established. From this theoretical knowledge, key areas to look upon will be identified and a design of experiments will be established. The goal is to develop a both efficient and effective product (catalyst) using a novel methodology developed from past research.
Predictions may be made about the suitability of possible catalysts by assuming that the mechanism of catalysis consists of two stages, either of which can be first:
The Electrolysis of Copper Sulphate Aim Analyse and evaluate the quantity of Copper (Cu) metal deposited during the electrolysis of Copper Sulphate solution (CuSo4) using Copper electrodes, when certain variables were changed. Results Voltage across Concentration of solution electrode 0.5M 1.0M 2.0M 2 5.0 10.6 19.5 4 10.5 19.8 40.3 6 14.3 26.0 60.2 8 15.2 40.4 80.3 10 15.0 40.2 99.6 12 15.1 40.0 117.0 Analysing/Conclusion The input variables in this experiment are; concentration of the solution and the voltage across the electrodes. The outcome is the amount of copper gained (measured in grams) at the electrodes. By analyzing the graph, we can see the rapid increase of weight gained for the 2.0 molar concentration as the gradient is steeper.
early 1990’s, no such material was known. In 1991, carbon nanotubes were discovered. Although not
brief overview on the structure and some properties of graphene, along with a presentation of graphene synthesis method and various applications.
Berger, M. (n.d.). Carbon Nanotubes could make t-shirts bulletproof. Retrieved March 11, 2014, from Nano Werk: http://nanowerk.com/spotlight/spotids1054.php
Carbon fibers were discovered in the late 1800s by Thomas Edison. The early lightbulbs Edison created used the carbon fibers as filaments. These carbon fibers used to create the early lightbulbs had a substantial tolerance to heat, but they lacked the tensile strength of modern carbon fibers. Edison used cellulose-based materials, such as cotton or bamboo, to make his carbon fibers. He used a method called “pyrolysis” to cook the bamboo at high temperatures in a controlled atmosphere to carbonize bamboo filaments, making them fire-resistant and capable of enduring intense heat needed for luminescence.
American Chemical Society. "Carbon nanotubes twice as strong as once thought." ScienceDaily, 16 Sep. 2010. Web. 5 Dec. 2013.
Over the past decades Nanoscience and nanotechnology is a springing up field of research interspersing material science and bionanoscience. Nanotechnology is an expanding area use to deal with materials in nano dimensions. Nanotechnology is the study and application of small object which can be used across all fields such as chemistry, biology, physics, material science and engineering. As the name indicates nano means a billionth or 10-9 unit. Its size range usually from 1-100nm (Nair et al., 2010). Nano size particles are quite unique in nature because nano size increase surface to volume ratio. So the main aim to study its minute size is to trigger chemical activity with distinct crystallography that increases the surface area (Sinha et al., 2009). Thus in recent years much research is going on metallic nanoparticle and its properties like catalyst, sensing to optics, antibacterial activity, data storage capacity and its use in agricultural productivity (Nair et al., 2010 & Sharma et al., 2009).