Carbon nanotubes (CNTs) have many desirable bulk properties, such as, very good mechanical strength, high thermal stability, and excellent electric conductance for potential use in a variety of applications. However, their surfaces often require modification in order to achieve functionality. An important first step in the adhesion to the nanotubes is often surface oxidation. To control the metallic and semiconducting properties of CNTs, electron withdrawing halogen atoms are usually covalently bonded to the surface.
In this present Thesis, single-walled CNTs (SWCNT) powder and multi-walled CNTs (MWCNT) paper were modified with gaseous oxygen and chlorine atoms. The following investigations were performed: (1) UV photo-oxidation of MWCNT paper at room temperature and atmospheric pressure with wavelengths from low-pressure Hg lamps (λ = 253.7 and 184.9 nm) that have sufficient energy to photo-dissociate gaseous oxygen producing mainly ozone and result in chemical surface modification of the samples; (2) SWCNT powder was surface oxidized at room temperature with gaseous oxygen atoms produced by low-pressure vacuum UV (VUV) photo-oxidation (λ = 104.8 and 106.7 nm); (3) MWCNT paper and SWCNT powder were surface oxidized without the presence of radiation at room temperature with gaseous oxygen atoms produced from a microwave (MW) plasma discharge of an argon and oxygen (Ar-O2) mixture; (4) UV photo-chlorination of MWCNT paper and SWCNT powder at room temperature with wavelengths from medium-pressure Hg lamps (centered at ca. 300 nm for Cl2 at ca. 100 torr gas pressure) and low-pressure Hg lamps (λ = 253.7 nm and 184.9 nm for HCl at ca. 40 torr gas pressure) that have sufficient energy to photo-dissociate gaseous Cl2 and HCl producing chlorine atoms and result in chemical surface modification of the samples.
The carbon-, oxygen- and chlorine-containing functional groups in the top 2–5 nm of the sample’s surface were analyzed by X-ray photoelectron spectroscopy (XPS).
|Adviser||Gerald A. Takacs|
|School||ROCHESTER INSTITUTE OF TECHNOLOGY|
|Subjects||Physical chemistry; Materials Science|
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