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Transcript of Carbon Nanotubes
Carbon Nanotubes Multi Wall Carbon
Nanotube Growth Advantges of CVD Growth by Chemical
Vapor Deposition (CVD) -A process in which thermal decomposition of a hydrocarbon vapor is achieved in the presence of a metal catalyst. Chemical Vapor Deposition HiPCO Synthesis Types Different Types of CNTs CNT APPLICATIONS Danny Raimondi and Kyle Hueston Carbon Nanotubes -Nanotubes are short in length when produced What are CNTs? -A Carbon Nanotube (CNT) is a tubular structure made of carbon atoms, having a diameter on the order of a nanometer but length in micrometers -This kind of structure was synthesized, studied, and reported by many researchers between the 50’s and 80’s. CNT’s didn’t catch wind until 1991 and Iijima’s detailed analysis of helical arrangement of carbon atoms on seamless coaxial cylinders. Being many fold stronger than steel in tension
Harder than diamond due to Carbon-carbon double bonds
More electrically conductive than copper
Thermal conductivity greater than that of a diamond. CNT’s have many extraordinary properties including: LITHIUM ION BATTERIES Flexible anodes constructed from CNT paper have a low theoretical energy density capacity. Through use of the Pulse Laser Deposition (Laser Ablation) process Silicon is deposited onto SWCNT paper to create composite paper which is both flexible and high-capacity. Advantages to using Si/SWCNT paper include:
they are able to achieve double the energy density of graphite
the total specific capacity of the paper is increased
the amount of deposited Si can be controlled through altering the PLD method. Coating ordinary paper in a CNT coating can also create conductive flexible anodes. This can lead to an equally effective, lightweight battery that can theoretically decrease the weight by 20%. These lightweight anodes could potentially increase the feasibility and effectivness of portable electronic devices, hybrid vehicles, and alternative energy systems such as solar or wind power. Laser Ablation Plasma Forming Arc Discharge Reactive Milling Electrochemical Hydrothermal Synthesis Solvothermal A highly scalable, low cost method without transition metal catalysts. Several synthetic strategies, including both physical and chemical methods, have been employed, with use of templates, precursors, and hydro-or solvothermal methods using binary and complex metal oxides, chalcohenides and carbides Synthesis using polyethylene/ water mixtures in the presence of nickel at 700˚-800˚C under 60-100 MPa Pressure http://en.wikipedia.org/wiki/File:Multi-walled_Carbon_Nanotube.png http://pubs.acs.org/doi/full/10.1021/jp1063403 nanotubes.epfl.ch Electrochemical deposition from organic solutions at room temperature, with formation and growth stimulated by transition metal catalysts such as iron and/or nickel Ball-milling and annealing or a pressure-vapor-condenser Soot formed from graphite electrodes during arc discharge -Laboratories and researchers began a scramble to find practical uses for CNT’s Plasma growth at low temperature A pulsed laser vaporizes a graphite target in a high temperature reactor as an inert gas is bled into the chamber Continuous flow high pressure carbon monoxide Most popular growth method
Low set up cost
Ease of scale up BIOMEDICAL APPLICATIONS In a study done by Robert Linhardt and others from the Rensselaer Polytechnic Institute in Troy, N.Y., a battery with a MWCNT cathode and aluminum anode was constructed. This battery was able to use human bodily fluids(sweat and blood) as the electrolite. This type of battery could be applied to powering healthcare tools such as pacemakers or other bodily implants. Applications that nanotubes could be used for require continuous fiber material that can be woven into cloth or braided Macroscale: big enough to use for practical applications There is a demand for Macroscale forms of nanotubes, the most important of which is nanotube yarn. http://www.scientificamerican.com/article.cfm?id=carbon-nanotubes-turn-off Carbon Nanotube growth must yield results of: Individual nanotubes being produced with a specific combination of diameter, length, strength, pliability, straightness, purity, and friction so that it may be spinnable into robust threads ARTIFICIAL MUSCLE Due to the high conductivity of doped CNTs, advancements have been made in developing artificial CNT muscles and tissues which can expand and contract when applied with an electrical charge. What makes CNT artificial muscles beneficial is the fact that they can operate at extreme temperatures. http://www.scientificamerican.com/article.cfm?id=cnt-artificial-muscle CVD Growth Methods HiPCO Because of the high voltage, these artificial limbs would not function as prostheses or replacement tissues, yet they can be used to operate artificial limbs and moving parts in space exploration or other aerospace applications. Catalytic Gas Flow CVD Floating Catalysts
CVD A gas phase CVD process that is both cheaper and more Scalabe, Partly because it does not use preformed catalyst particles, unlike alternative CVD processes for SWNTs Process is technically simple and does not need a substrate or any difficult to remove ceramics. Less stable than other methods due to impurities accumulated during growth
of the nanotubes, as they grow and
move away from the heat source. Theoretical Tensal Strength: 100x stronger than steel and 1/16th the weight Electrical Conductivity: Higher carrying capacity than gold or copper C source- a Catalyst source, Consisting of ferromagnetic Metals such as but not limited to Nickel, Iron, and Cobalt. Can grow millimeter long
nanotubes, from a variety of C sources Allows for control of the
composition of SWNT or
MWNT nanotubes depending
on the C source. Thermal Conductivity: comparable to diamond or in-plane graphene Structure: Cyllindrical tube comprised of 6-membered carbon rings. small diameters prove to create stronger structures. Issues with widespread application lie with impurity, selectivity and dispersibility http://www.sigmaaldrich.com/technical-documents/articles/material-matters/manufacturing-characterization.html Structure: Concentric CNTs Conductivity and Chemical Resistance: In many cases the conductivity and chemical resistance is much higher in MWCNTs than SWCNTs Can have "telescoping" properties to provide mechanical benefits, typically in double-walled CNTs http://www.sciencemag.org/content/289/5479/602.full The biggest problem in producing CNTS lies with the purity of the structure. BUCKYPAPER Buckypaper is the name given to macroscopic CNT paper. This paper itself can be applied to many different objects, as it maintains many CNT properties. HEAT DISPERSION This paper can prevent computers and other electronics from overheating due to its extreme thermal conductivity. https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&docid=fqcmbPHr48ZL5M&tbnid=z1supWF0S8LKSM:&ved=0CAQQjB0&url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FBuckypaper&ei=I8wrUcXBLMekrQGqhYGIAg&bvm=bv.42768644,d.aWc&psig=AFQjCNGLJQtCh81AlQAPrdUCXFlfBDBPiQ&ust=1361911031428456 Electrical Advantages Buckypaper can be applied widely as a current-carrying material, whether it is illuminating television displays or being arranged on the exterior of airplanes to prevent damage from lightening strikes. Military If mass produced, this paper could be layered and form a composite to serve as armor plating. It can also be used on aircrafts to prevent electromagnetic interference, as well as radar detection IN CONCLUSION Health This paper can potentially grow tissue such as nerve cells or other specialized cells depending on how it is synthesized. Functionalized Purposes Due to the methods in which they are manufactured, CNTs are able to act as specialized sensors or filters for certain compounds http://www.reade.com/western-region-(usa)/5269 Studies have also shown that CNTs, when attached to tumors can effectively absorb neutrons from a targeted beam and generate localized alpha radiation as a means to kill cancer. Wearable bio monitors can also be created in order to monitor medical conditions or vital signs http://news.bbc.co.uk/2/hi/science/nature/7038686.stm https://www.google.com/search?q=cnt+cell+growth&aq=f&um=1&ie=UTF-8&hl=en&tbm=isch&source=og&sa=N&tab=wi&authuser=0&ei=gtorUfPtLO6GyQHpm4Ag&biw=1600&bih=785&sei=htorUePTDMjcyQHfq4DQAg#um=1&hl=en&authuser=0&tbm=isch&sa=1&q=cnt+airplane&oq=cnt+airplane&gs_l=img.3...24070.27449.0.27922.214.171.124.0.0.0.74.4126.96.36.199...0.0...1c.1.4.img.HlyonHCtMWQ&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.&bvm=bv.42768644,d.aWc&fp=a1ee18ef7dd7ed9&biw=1600&bih=785&imgrc=gggmEwmucNPcZM%3A%3B0VZ0RwcHLYuOnM%3Bhttp%253A%252F%252Fwww.cntraveler.com%252Fdaily-traveler%252F2012%252F09%252Fwhat-would-sully-do-turbulence-lightning-planes-air-travel%252F_jcr_content%252Fpar%252Fcn_contentwell%252Fpar-main%252Fcn_colctrl%252Fpar-col2%252Fcn_blogpost%252Fcn_image.size.airplane-turbulence-lightning.jpg%3Bhttp%253A%252F%252Fwww.cntraveler.com%252Fdaily-traveler%252F2012%252F09%252Fwhat-would-sully-do-turbulence-lightning-planes-air-travel%3B508%3B381 Carbon Nanotubes can be constructed in a variety of ways. They yield a wide range of applications and can be mechanically or chemically altered in order to achieve specific properties. Commercialization of macroscopic CNT aggregates such as yarn or buckypaper is in its early stages, yet demand for these products is rapidly increasing. http://www.rsc.org/chemistryworld/2013/01/carbon-nanotube-fibres-wetspinning http://www.nano.org.uk/news/nov2008/latest1663.htm Is quickly emerging as one of the most scalable and least expensive methods for producing high quality single-walled nanotubes (SWNT) and Multi walled nano tubes (MWNT), thus, there is great need for a better understanding of the variables, which define the resulting products Instead of thin films, which coalesce into catalyst islands during heating, catalyst material is continuously added during floating-catalyst growth, and catalyst particles form as reactants, decompose and deposit on substrate surfaces. As a result, nanotube diameters are affected by parameters that do not apply to conventional thin film CVD growth, such as catalyst solution concentrations. -Of the few reports on diameter control using this method, the conclusions with regard to catalyst concentrations have not always been consistent, with increasing concentrations resulting in either reduced diameters, increased diameters, or showing little influence. Of these reports, some examine only single-walled tubes , while those studying multiwalled tubes use vastly different reaction temperatures (ranging from 675˚C to 1150˚C), and catalyst concentrations (varying ferrocene-hydrocarbon molar ratios). Control of nanotube diameters is important, and the mechanisms by which the catalyst concentration can affect nanotube dimensions must be understood. Thin Film Catalysts Nanotube diameters are controlled by varying the metal film deposition thickness Results of Types of CVD and Other Nanotube Growth Methods Fluidized Bed CVD, Laser Oven, Arc Discharge and HiPCO Produce short nanotubes in the 0.05-3µm range Substrate Growth and Catalytic
Gas Flow CVD Produces Long nanotubes Up to a centimeter Compared to Arc Discharge and Laser Ablation methods, CVD is seen as a simple economic technique for synthesizing at low temperature and ambient pressure. CVD produces CNT’s with low crystallinity compared to those produced by Arc and laser methods. But CVD has the advantage over both competitors when it comes to yield and purity. When it comes to structure control or CNT architecture CVD is the only answer. It offers harnessing hydrocarbons in state (gas, liquid, solid) Enables the use of various substrates Allows CNT growth in a variety of forms such as: Powders
Thin or thick Films
Aligned or entangled
Straight or coiled
A desired architecture of nanotubes on predefined sites of a patterned substrate It also offers better control on the growth parameters. Formation of CNT Fibers Synthetic fibers are usually created from a concentrated, viscous liquid. This liquid is a melt or solution of the starting material, which is aligned by flow processing and converted into a fiber through cooling or solvent removal Both liquid and solid state spinning have been adapted for growth of CNT fibers Liquid State Spinning Issues arise due to CNTS not melting as a result of their high stiffness and high molecular weight and they are not soluble in organic or aqueous solvents. CNTs tend to form bundles rather than dissolving because of the strong van der Waals forces between their side walls. Thus resulting in lack of control and alignment of nanotubes unless they are dispersed at the molecular level. Various techniques have been created to overcome this problem. CNT dispersions can be stabilized in surfactant solution and super acids, both of these fluid phases have been used to spin CNT-based fibers Solid State Spinning Circumvents the dissolution problem by drawing a fiber from a vertically grown array of nantoubes or by drawing directly from and aerogel in the furnace. Through chemical and mechanical alterations, the properties of CNTs can be changed so that they will yield macroscopic benefits in various fields of application Nanotube Responsive Materials, Jayasinghe; MRS Bulletin, Vol 35. Sept 2010 Nanotube Responsive Materials, Jayasinghe; MRS Bulletin, Vol 35. Sept 2010 Kumar, Mukul, and Yoshinori Ando. "Chemical vapor deposition of carbon nanotubes: a review on growth mechanism and mass production." Journal of nanoscience and nanotechnology 10.6 (2010): 3739-3758. Kumar, Mukul, and Yoshinori Ando. "Chemical vapor deposition of carbon nanotubes: a review on growth mechanism and mass production." Journal of nanoscience and nanotechnology 10.6 (2010): 3739-3758. Nanotube Responsive Materials, Jayasinghe; MRS Bulletin, Vol 35. Sept 2010 Carbon Nanotube based neat fibers, Behatbu; Nanotoday, Vol 3. Oct-Dec 2008 Dimensional control of multi-walled carbon nanotubes in ﬂoating-catalyst CVD synthesis, Mckee. March 2009 Carbon Nanotube based neat fibers, Behatbu; Nanotoday, Vol 3. Oct-Dec 2008 Carbon Nanotube based neat fibers, Behatbu; Nanotoday, Vol 3. Oct-Dec 2008 Kumar, Mukul, and Yoshinori Ando. "Chemical vapor deposition of carbon nanotubes: a review on growth mechanism and mass production." Journal of nanoscience and nanotechnology 10.6 (2010): 3739-3758.