The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
Aalto

Aerosol Synthesis of Carbon Nanotubes and Nanobuds

Anton Anisimov

Doctoral dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Faculty of Information and Natural Sciences for public examination and debate in Auditorium U154 at the Aalto University School of Science and Technology (Espoo, Finland) on the 9th of April 2010 at 12 noon.

Overview in PDF format (ISBN 978-952-60-3087-6)   [2568 KB]
Dissertation is also available in print (ISBN 978-952-60-3086-9)

Abstract

This thesis presents the results of experimental investigations of single-walled carbon nanotube (SWCNT) and nanobud synthesis. These carbon nanomaterials were synthesized by two different methods based on CO disproportionation on the surface of iron particles produced by hot-wire generator and ferrocene decomposition methods.

Studies of CO disproportionation in the presence of etching molecules (H2O and CO2) led to the discovery of a novel hybrid carbon material — SWCNTs covered by covalently bonded fullerenes — carbon nanobuds. The reagent concentrations required for nanobud synthesis were found to be between 45 and 245 ppm for H2O and between 2000 and 6000 ppm for CO2. The growth mechanism of the nanobuds and their properties were examined.

On the basis of in situ sampling investigations, the kinetics of the SWCNT growth was studied. For temperatures of 804, 836, 851, and 915 °C, the average growth rates were found to be 0.67, 1.11, 1.01, and 2.70 µm/s, respectively. It was found that the growth rate constant complies with the Arrhenius dependence with an activation energy of Ea = 1.39 eV, which can be attributed to the diffusion of carbon atoms in the solid iron catalyst.

A new method for separating bundles and individual SWCNTs is proposed. This method is based on the fact that bundled SWCNTs coming from the reactor are charged, while individual SWCNTs remain electrically neutral. Studies of the charging phenomenon revealed that SWCNT bundles were charged (up to 99%) and could carry up to 5 elementary charges. It is proposed that SWCNT bundles were positively charged due to electron emissions and negatively charged due to the emission of impurities from the surface.

As a potential SWCNT application, a simple and direct thermo-compression method for integrating SWCNT films with adjustable thicknesses, transparency, and conductivity into polymer films is demonstrated. The produced SWCNT/polyethylene composite films exhibited good optical transparency and conductivity as well as high mechanical flexibility. SWCNT/polyethylene thin films demonstrated excellent cold electron field emission properties.

This thesis consists of an overview and of the following 7 publications:

  1. Anton S. Anisimov, Albert G. Nasibulin, Hua Jiang, Pascale Launois, Julien Cambedouzou, Sergey D. Shandakov, and Esko I. Kauppinen. 2010. Mechanistic investigations of single-walled carbon nanotube synthesis by ferrocene vapor decomposition in carbon monoxide. Carbon, volume 48, number 2, pages 380-388.
  2. Albert G. Nasibulin, David P. Brown, Paula Queipo, David Gonzalez, Hua Jiang, Anton S. Anisimov, and Esko I. Kauppinen. 2006. Effect of CO2 and H2O on the synthesis of single-walled CNTs. physica status solidi (b), volume 243, number 13, pages 3087-3090.
  3. Albert G. Nasibulin, Peter V. Pikhitsa, Hua Jiang, David P. Brown, Arkady V. Krasheninnikov, Anton S. Anisimov, Paula Queipo, Anna Moisala, David Gonzalez, Günther Lientschnig, Abdou Hassanien, Sergey D. Shandakov, Giulio Lolli, Daniel E. Resasco, Mansoo Choi, David Tománek, and Esko I. Kauppinen. 2007. A novel hybrid carbon material. Nature Nanotechnology, volume 2, number 3, pages 156-161.
  4. Albert G. Nasibulin, Anton S. Anisimov, Peter V. Pikhitsa, Hua Jiang, David P. Brown, Mansoo Choi, and Esko I. Kauppinen. 2007. Investigations of NanoBud formation. Chemical Physics Letters, volume 446, numbers 1-3, pages 109-114.
  5. David Gonzalez, Albert G. Nasibulin, Sergey D. Shandakov, Hua Jiang, Paula Queipo, Anton S. Anisimov, Taku Tsuneta, and Esko I. Kauppinen. 2006. Spontaneous charging of single-walled carbon nanotubes: a novel strategy for the selective substrate deposition of individual tubes at ambient temperature. Chemistry of Materials, volume 18, number 21, pages 5052-5057.
  6. Albert G. Nasibulin, Sergey D. Shandakov, Anton S. Anisimov, David Gonzalez, Hua Jiang, Marko Pudas, Paula Queipo, and Esko I. Kauppinen. 2008. Charging of aerosol products during ferrocene vapor decomposition in N2 and CO atmospheres. The Journal of Physical Chemistry C, volume 112, number 15, pages 5762-5769.
  7. Albert G. Nasibulin, Andrei Ollikainen, Anton S. Anisimov, David P. Brown, Peter V. Pikhitsa, Silja Holopainen, Jari S. Penttilä, Panu Helistö, Janne Ruokolainen, Mansoo Choi, and Esko I. Kauppinen. 2008. Integration of single-walled carbon nanotubes into polymer films by thermo-compression. Chemical Engineering Journal, volume 136, numbers 2-3, pages 409-413.

Keywords: carbon nanotube, carbon nanobud, synthesis, etching, mechanism, charging phenomena, field emission

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Last update 2011-05-26