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An introduction to synthesis & applications of carbon (2)

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An introduction to synthesis & applications of carbon (2)

  1. 1. NANOTECHNOLOGY- CARBON NANOTUBES Presented by- Nithya Nair
  2. 2. CONTENTS Nanotechnology Introduction to the topic History Why carbon nanotubes? Fundamentals for Hydrogen Storage i. Physisorption ii.Chemisorption Comparison table Synthesis Doping Conclusion References
  3. 3. NANOTECHNOLOGY Nanotechnology is the creation of useful/functional materials, devices and systems (of any useful size ) through control manipulation of matter on the 1-100nm length scale and the use of novel phenomena and properties which arise because of nanometer length scale.Nanometer One billionth of a meter (10-9 m) Hydrogen atom 0.04nm Proteins 1-20nm Chemically reactivity differs . Improved mechanical properties Increased surface area New chemical formulation
  4. 4. Source: Silicon Valley Toxics Coalition
  5. 5. INTRODUCTIONCarbon nanotubes are extremely thin hollow cylinders made of carbon with pores thatcan store gases by the phenomena of adsorption.Various carbon nanotubesSingle walled nanotubes (SWNT) - diameter range of 0.4 to 3nm .Multi walled nanotubes (MWNT) - several sheets, arranged concentrically inincreasingly larger diameters with diameters in the range of 1.4 to 100 nm.Metal doped nanotubes - Obtained by doping of various metals to carbon nanotubes.
  6. 6. HISTORY After Kroto & Smalley discovered Fullerene, one of carbon allotropes (a cluster of 60 carbon atoms: C60) for the first time in 1985, Dr.Iijima, a researcher for this new material , in Japan discovered in 1991, a thin long straw-shaped carbon Nanotubes during TEM analysis of carbon clusters.
  7. 7. PROPERTIES A carbon atom in nanotube forms a hexagonal lattice of sp² bond with three other carbon atoms. As the inner diameters of the tubes are extremely thin down to about several nanometers, the tubes are called Nanotubes. Thermal conductivity (>3000 W/m-K), The elastic ability to extend ≈5.8% of its original length More appealing still is the disproportionately large surface area to volume that these materials possess , for this allows for a greater potential of interactions, both physical or chemical in nature
  8. 8. APPLICATIONS IN HYDROGEN STORAGE Depleting non- renewable source of energy prompting us to move to an energy resource which is abundantly available and which is eco- friendly as well. „Hydrogen‟ ,sought as future fuel because of high energy content than any other fuel, at least 3 times than gasoline. Advantage- clean fuel, byproduct only water. Disadvantage- low energy density by volume. So difficult to store and transport.
  9. 9. WHY CARBON NANOTUBES FOR H2 STORAGEAvailable techniques for hydrogen storage- As cryogenic liquid As pressurized gas As physical combination with metal hydrides/complex hydrides on board production By reform of methanol Carbon nanotubes
  10. 10. HYDROGEN STORAGE FUNDAMENTALSPhysisorption Based on Vander Waal‟s interaction. Stem from intermolecular forces between atoms that result from instantaneous charge distribution in atoms & molecules when they approach each other. The interaction energy, also called the London Dispersion forces Adsorption on a flat carbon surface depends on the adsorption stereometry. An average value would be 4-5 kj mol⁻1.This represents a very weak interaction .Therefore, hydrogen is desorbed with increasing temperature, and a very little hydrogen adsorption is observed on carbon at elevated temperature.
  11. 11. Source:greener-industry.org.uk website
  12. 12. CHEMISORPTION If the π-bonding between the carbon atom were to be fully utilized, every carbon atom could be a site for chemisorptions of one hydrogen atom. Desorption results of nanotubes treated with chemisorbed hydrogen, however, can only be released at higher temperatures. Hydrogen storage in CNTs by chemical reaction, on the other hand , has largely been discounted as irreversible and thus technologically less relevant
  13. 13. TABLE 1.1 VARIOUS SAMPLES OF CARBON NANOTUBES AND THEIR HYDROGEN STORAGE CAPACITY [11],[14]Sample % Purity H₂ (wt%) T(K) P(MPa) Ref.SWNTs Assumed 100 5-10 133 0.04 (A.C. Dillon et al., 1997)SWNTs 50 4.2 300 10.1 (C. Liu et al,1999)SWNTs High 8.25 80 7 (Y. Ye et al, 1999)SWNTs Purified 1.2 Ambient 4.8 (Smith Jr, Bittner,Shi, Jhonson, & Bockrath, 2003)SWNTs 90 vol% 0.63 298 - (Ritschel et al., 2002)SWNTs Purified 6 77 0.2 (Pradhan et al., 2002)SWNTs Unpurified 0.93 295 0.1 (Nishimaya et al., 2002)SWNTs Unpurified 0.37 77 0.1 (Nishimaya et al., 2002)MWNTs Purified 0.25 ~300-700 Ambient (Wu et al., 2000)MWNTs Unpurified 0.5 298 - (Ritschel et al., 2002)MWNTs High 5-7 300 1.0 (Y. Chen et al., 2001)MWNTs High, acid treated 13.8 300 1.0 (Y. Chen et al., 2001)MWNTs High 0.7-0.8 300 7.0 (Badzian, Breval & Piotrowski, 2001)
  14. 14. SYNTHESIS Source: B lue penguin reportSchematics of a laser ablation set-up, reproduced from B. I. Yakobson and R.E. Smalley, American Scientist 85, 324 (1997).
  15. 15. METAL DOPED CARBON NANOTUBES Metal doping provides additional binding energy state of hydrogen. Transition metals doped- V, Ti, Pt and Pd. Storage condition : 30 atm, 300K Enhanced hydrogen storage capacity on doping, the reversible hydrogen storage capacity of doped nanotubes. April 2011 Journal of the American Chemical Society
  16. 16. CHALLENGES TO OVERCOME High accessible surface, large free pore volume & strong interactions- Three main demand for high hydrogen storage capacity. A more accurate & practical approach towards studying thermodynamics, Kinetics, Adsorption /Desorption of nanotubes. Mass production of carbon nanotubes with controlled microstructures at a reasonable cost.
  17. 17. REFERENCES1. ZHANG, Ei- fei; LUI, Ji-ping; LU, Guang- shu. “Preparation of Isolated Single Wall Carbon Nanotubes With High Hydrogen Capacity.”[J],(The Chinese Journal Of Process Engineering),Vol.6, No.3, June 2006.2. Baughman, Ray H.; Anvar A. Zakhidov, and Walt A. De Heer. "Carbon Nanotubes: The Route toward Applications." Science 297 (2002): 787-92.3. Iijima,S., Nature(1991) 354, 56.4. http://www.energy.gov5. U.S. Department of Energy‟s Efficiency and Renewable Energy Website. https://www1.eere.energy.gov/hydrogenandfuelcells/storage/current_technology. html(2010).6. KUNG Chaoi, “Carbon Nanotubes for Hydrogen Storage”. Nov. 2002.7. Yunjin, “Hydrogen Storage using carbon Nanotubes.” Hefei University of Technology, China8. DILLON, A.C.; GENNET, T.; GELLEMEN, J.L.; JONES, K.M.; PARILLS, P.A. and Heben, “Optimization of Single –Wall Nanotube Synthesis For Hydrogen Storage”. National Renewable Energy Laboratory.
  18. 18. 10. NIKITIN, Anton; LI, Xialolin; ZHANG, Zhang; OGASAWARA, Hirohita; DAI, Hongjie & NILSSON, Anders. “Hydrogen Storage in Carbon Nanotubes through the Formation of Stable C-H Bonds” Nano Letters, 2008 Vol.8, No.1 (162-167) .11. Dillon, A. C.; K. M. Jones; T. A. Bekkedahl; C. H. Kiang, D. S. Bethune, and M. J. Heben. "Storage of hydrogen in single-walled carbon nanotubes." Nature 386 (1997): 377-79.12. Liu, C., Y. Y. Fan, M. Liu, H. T. Chong, H. M. Cheng, and M. S. Dresselhaus. "Hydrogen Storage in Single-Walled Carbon Nanotubes at Room Temperature." Science 286 (1999): 1127-129.13. “Chemical Activation Of Single Walled Carbon Nanotubes for Hydrogen Adsorption’’. SMITH, Milton R.; BIITTNER, Edward W.; SHI, Wei & BOCKRATH, C. Bradely.14. Chen, Y. L., B. Liu, J. Wu, Y. Huang, H. Jiang, and K. C. Hwang. "Mechanics of hydrogen storage in carbon nanotubes." Journal of the Mechanics and Physics of Solids 56 (2008): 3224-241.15. http://www.nanowerk.com16. http://www.ewels.info/science/publications/papers/2008.DopingChapter.pdf

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