Ab initio studies of vacancy‐defected fullerenes and single‐walled carbon nanotubes

Abstract

The structures, stabilities, and electronic properties of the singlevacancy-defected fullerenes, C 60 and C 70 , and the single-and double-vacancy-defected single-walled carbon nanotubes (SWCNTs) were studied within density functional theory. The isomerization barriers for the single-vacancy-defected C 60 on the triplet potential energy surface (PES) are lower than those on the singlet PES. The symmetric double-vacancy-defected (10,0) SWCNT is the most stable one among the models investigated. According to the analyses of frontier molecular orbitals (FMOs), nature bond orbitals, and local density of states, introduction of vacancy on the SWCNT decreases the band gap of semiconducting SWCNT, increases the band gap of conducting SWCNT, destructs the conjugation of the FMOs, and gives rise to enhanced chemical activity.Because of icosahedral (I h ) symmetry, all the carbon atoms are equivalent in C 60 . While in C 70 , there are five different types of symmetrically distinct carbon atoms, thus resulting in many possibilities for vacancy. For simplicity, we only considered the situation that the missing carbon atom is located in the pentagon at the pole of C 70 . Geometry optimizations were performed with the hybrid DFT method, B3LYP [36,37], with the standard 6-31G(d) basis set, and were followed by single-point calculations with B3LYP/6-311G(d). Natural bond or-LIU, TIAN, AND WANG 3442 INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY

Theoretical Studies of Substitutionally Doped Single-Walled Nanotubes

“…In particular, defected [81,[110][111][112] and doped nanotubes [35,36,45,110,113,114] have been the focus of our attention. Since nanomaterials have such great potential for application in biological systems, sensory technology, electronics, and catalysis, their fundamental chemistry warrant further investigation.…”

Nicotine adsorption on single wall carbon nanotubes

“…After optimizing the vacancy-SWCNT structure, two of the di-coordinate carbons, from the defect, combine to form a pentagonal site in a symmetric geometry, thus leaving the third one with a dangling bond. This is already expected for (8,0) SWCNT from theoretical calculations [33,34]. It is pertinent to remember that the presence of vacancies introduces uncoordinated atoms on the SWCNT [30] and this defect can give rise to magnetic properties similar to edge-effects in the graphene nanoribbons [35].…”

Stable Au–C bonds to the substrate for fullerene-based nanostructures

“…We therefore hypothesize that the damaged fullerenes in our study are C 59 molecules, an assumption discussed below. C 59 molecules have the highest energetic stability (difference between the cluster energy and the sum of the energy of the individual C atoms) after C 60 [23–25]. These findings are corroborated by total-energy DFT simulations.…”