Adsorption to carbon nanotubes

2005 2005

Other formats: Order a copy

Abstract (summary)

We have probed the adsorption property of single-wall carbon nanotube (SWNT) bundles using the temperature-programmed desorption technique.

The SWNT sample cleanliness effect on the 4He adsorption was investigated. Room air contacting significantly decreased the 4He adsorption capacity.

The 4He adsorption vs. pump-out temperature on SWNT samples and on charcoal was obtained. A two-state binding site model did not fit well to the SWNT data, while it fit well to the charcoal data indicating the 4He binding energy on charcoal to be 400 ± 32 K which agreed with other group's value. Using the desorption rate isotherm analysis technique, we obtained coverage dependant 4He binding energies on SWNT bundles. Our values agreed with other group's results at near 400 K where the coverages overlapped, and our energy value increased to a much higher value at near 900 K at lower coverages beyond the lowest coverage of other group.

The 4He addition temperature was changed from 273 K to lower values in the 8–40 K range for three SWNT samples and a charcoal sample. While the 4He adsorption was not sensitive on the addition temperature on charcoal, it was different on SWNT samples. Some sites were not accessible for 4He atoms at low temperatures. The 4He access to these sites increased as the gas addition temperature increased, and at 35 K and above a full 4He access to a 273 K dosed level was observed. An activated diffusion model fit to the 4He amount, vs. gas addition temperature data yielded the activation energy for diffusion to be 28 ± 14 K and 47 ± 6 K on two samples. One sample showed more restricted 4He access for 4He at 15 K. This sample had more impurities.

Codesorption measurements were done on SWNT samples. Xe in smaller quantity (6% level) than 4He and H2, suppressed the adsorption of other gases to the background level. H2 suppressed 4 He to the background level, when added in equal amount at 273 K. However when 4He was added at 273 K and H2 was added later at 19 K, H2 did not suppress the 4He adsorption. Equal mixture doses of 4He and 3He at 273 K yielded 8.4 times more 4He binding than 3He. This strong isotope selectivity agreed with the predicted quantum sieving effect.

Indexing (details)

0611: Condensation
Identifier / keyword
Pure sciences; Adsorption; Carbon nanotubes; Helium; Hydrogen; Xenon
Adsorption to carbon nanotubes
Kahng, Yung Ho
Number of pages
Publication year
Degree date
School code
DAI-B 66/02, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
9780496976669, 0496976664
Hallock, Robert B.
University of Massachusetts Amherst
University location
United States -- Massachusetts
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
Access the complete full text

You can get the full text of this document if it is part of your institution's ProQuest subscription.

Try one of the following:

  • Connect to ProQuest through your library network and search for the document from there.
  • Request the document from your library.
  • Go to the ProQuest login page and enter a ProQuest or My Research username / password.