Energetics and Electronic Structures of Individual Atoms Adsorbed on Carbon Nanotubes

Abstract

The adsorption of individual atoms on the semiconducting and metallic single-walled carbon nanotubes (SWNT) has been investigated by using the first principles pseudopotential plane wave method within density functional theory. The stable adsorption geometries and binding energies 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 depends 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. Although 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 a 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. 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 1D nanomagnets or nanoconductors, conducting connects, and so forth.

Hydrogen storage capacity of Ti-doped boron-nitride andB∕Be-substituted carbon nanotubes

“…Ti is bound to ͑8,0͒ SWBNT surface with E b of 1.09 eV without facing energy barrier. This displays a lower binding energy than that is obtained for SWNT ͑2.2 eV͒, 35,36 but it is still strong. Among possible adsorption sites, the most energetic one is found to be near the hollow site, where Ti atom is slightly displaced toward B and N atoms.…”

Probing molecular interactions on carbon nanotube surfaces using surface plasmon resonance sensors

“…4,5 A comprehensive understanding of these forces at atomic and molecular level still remains a challenge. A great deal of computational 6,7 and experimental effort 3,5,7,8 has been devoted to elucidate these interactions. New techniques with improved sensitivities are needed to probe the dynamics of organic molecules on the surface of low-dimensional carbon nanomaterials.…”

Functionalization of carbon-based nanostructures with light transition-metal atoms for hydrogen storage

“…We found that the Ti atom favors the hexagonal site ͑above the center of the hexagon͒ and its binding energy was calculated to be 1.54 eV. Although the favorable adsorption site is the same for both ͑8,0͒ and ͑12,0͒ tubes, the binding energy of the latter ͑having larger radius, r = 4.7 Å͒ is approximately 0.6 eV smaller than that of the ͑8,0͒ tube 37,38 having r = 3.2 Å. This curvature effect is expected, since C 2p and Ti 3d hybridizations are enhanced at small radius.…”