A study of adsorption of single atoms on carbon nanotubes
Author
Durgun, Engin
Advisor
Çıracı, Salim
Date
2003Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
The adsorption of individual atoms on the semiconducting and metallic singlewall
carbon nanotubes (SWNT) have been investigated by using first-principles
pseudopotential plane wave method within Density Functional Theory. The stable
adsorption geometry and binding energy have been determined for a large
number of foreign atoms ranging from alkali and simple metals to the transition
metals and group IV elements. We have found that the character of the bonding
and associated physical properties strongly depend on the type of adsorbed
atoms, in particular on their valence electron structure. Our results indicate that
the properties of SWNTs can be modified by the adsorbed foreign atoms. While
the atoms of good conducting metals, such as Zn, Cu, Ag and Au, form very
weak bonds, transition metal atoms, such as Ti, Sc, Nb and Ta, and group IV
elements C and Si are adsorbed with relatively high binding energy. Owing to the
curvature effect, these binding energies are larger than the binding energies of the
same atoms on the graphite surface. We have showed that the adatom carbon
can form strong and directional bonds between two SWNTs so that the tubes are
connected. These connects can be used to produce nanotube networks or grids.
Most of the adsorbed transition metal atoms excluding Ni, Pd and Pt have a
magnetic ground state with a significant magnetic moment. Our results suggest
that carbon nanotubes can be functionalized in different ways by their coverage
with different atoms, showing interesting applications such as one-dimensional
nanomagnets or nanoconductors and conducting connects etc.
Keywords
ab initiocoating
metal
binding
adsorption
density functional theory
carbon nanotube
first principles