The production of single-walled carbon nanotubes by a CVD method and their characterisation by various techniques
Seifi, M 2007, The production of single-walled carbon nanotubes by a CVD method and their characterisation by various techniques , PhD thesis, Salford : University of Salford.
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In this work, Chemical Vapour Deposition (CVD) was used to prepared Single- Walled carbon nanorube (SWNT) samples. In developing the production techniques a large number of parameters were varied during the course of work resulting in the successful repeatible growth of single-walled carbon nanotubes. Methane was used as a carbon-carrier gas decomposed at 950°C over a catalyst material consisting of 1.5% and 2% by wt Fe chemically deposited on a MgO support. The activity of the catalyst and the surround atmosphere were controlled by varying the flow ratio of Ar and H2 gases as well as the flow of the carrier gas. Metallic catalyst particles together with the support material were treated by consecutive acid treatments in HNOs and HC1 at 50°C to reduce their concentration. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were used to show the presence of nanotubes and also to measure the diameter of SWNT bundles and the size of carboneous materials. Images of SEM and TEM show a large number of nanotubes in the samples. Raman scattering was used to probe the electronic properties and hence derive the diameters of the SWNT. For this reason, Raman spectra of SWNT samples were measured in the radial breathing mode (RBM) and Tangential mode (TM) ranges using three different laser lines. Raman spectra show a diameter distribution of nanotubes ranging from 0.97 to 1.45 nm. Microgravimetric measurements of nitrogen and hydrogen adsorption were then applied to these samples to evaluate the specific surface areas Brunauer, Emmett and Teller (BET) and HT storage capacities of the samples and also derive information about the diameter of the pores in the samples by analysing the hysteresis loop in the N2 isotherm. The BET measurements show a different surface area for samples 350 m2/g for sample 1 and 227 m2/g for sample 2. Because there is a direct relationship between the surface area and hydrogen adsorption so the different storage capacity are shown for samples 0.5wt% for sample 1 and 0.25wt% for sample 2.
|Item Type:||Thesis (PhD)|
|Schools:||Colleges and Schools > College of Science & Technology|
Colleges and Schools > College of Science & Technology > School of Computing, Science and Engineering
|Depositing User:||Institutional Repository|
|Date Deposited:||03 Oct 2012 14:34|
|Last Modified:||20 Aug 2013 18:34|
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