| Summary: | In this thesis, the electronic structure and reactivities of the perfect, defected, and
doped single-walled carbon nanotubes (SWCNTs) have been studied by various
theoretical methods, including density functional theory, semiempirical methods, and
force fields. Among different defects of the SWCNTs, we have concentrated our studies
on the vacancy defect and substitutional^ doped defect.
Of the vacancy defected SWCNTS, we first studied their geometries, energetics, and
electronic structures. After comparing the vacancy defected SWCNTs with the perfect
SWCNTs, we found that the vacancy defect introduces localized electronic states near the
Fermi level, thus enhancing the chemical reactivity of the SWCNTs.
We then studied the reaction mechanisms of the vacancy defect on the (5,5) SWNCT
with NO and O₃. We have discovered that the reaction between NO and the vacancy
defect provides a possible way to fabricate the substitutionally N-doped SWCNTs. We
also obtained a microscopic understanding of the ozonization at the vacancy defect site of
the SWCNT.
To further understand the doping effects, we have studied the precious metal Ptdoped
SWCNTs at different positions of the (5,5) SWCNT rod. We found that the doping
of Pt in the SWCNT rod results in localized states at Pt, thus rendering Pt as the active
center in chemical reactions. We found that the doping of Pt in the middle of the sidewall
of the nanorod has a stronger interaction with adsorbates (e.g., H₂ and C₂H₄) than the
doping of Pt at the hemispheric caps of the nanorod. === Science, Faculty of === Chemistry, Department of === Graduate
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