Hiral effects of single‐wall carbon nanotube fluorination and hydrogenation

Abstract

ABSTRACT:The results of calculations of the electronic and energy characteristics of atomic hydrogen and fluorine adsorption processes on an external surface of single-wall hiral carbon nanotubes (n, m) are represented. Molecular cluster model within a framework of quantum chemical semiempirical schemes modified neglect of diatomic overlap (MNDO) and parametric method 3 (PM3) has been used. Sorption properties of (4,1), (4,2), (4,3), (5,1), (5,3), (5,4), (6,1), (6,2), (6,3), (6,4), and (6,5) tubes have been considered. Periodical behavior of the chemical bond and activation energies as nanotube diameter functions has been found. It appeared that (4,2), (4,3), and (5,1) nanotubes show more effective adsorption processes and (5,3), (5,4), (6,2), and (6,3) tubes are not advantageous for the chemisorptions.

The chiral effect of adsorption of univalent atoms and diatomic molecules on the surface of carbon nanotubes

“…That is, chiral CNTs with the most favor able adsorption energy add atomic hydrogen with the lowest activation energy. Similar results were obtained using both semiempirical methods, MNDO and PM3 [7][8][9].…”

“…The experiment described above indirectly sub stantiated the chiral adsorption effect predicted by the authors earlier [7][8][9]. These works contain the results of quantum chemical calculations of atomic hydroge nation and fluorination processes obtained for (6,4), and (6, 5) chiral carbon nanotubes.…”

“…An oscillating dependence of fluorine adsorp tion energies was observed. The (4, 2), (4, 3), and (5, 1) nanotubes had the highest chemical bond energy and the lowest energy barrier, whereas (5, 3), (5,4), (6,2), and (6, 3) nanotubes had the lowest chemical bond energy and the highest activation energy [7][8][9].…”

“…Electrons are more localized in them than in conducting CNTs, and car bon atom p orbitals are saturated and have low reactiv ity with respect to atomic hydrogen adsorption. A con sequence of this is the highest activation energy and lowest energy of C-H bonds formed [7][8][9].…”

“…The main charge carriers in these CNTs (electrons) are not localized. For this reason, atomic carbon p orbitals participating in the formation of chemical π bonds are unsaturated and have enhanced reactivity [7][8][9].…”