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We report comparative study of ozone adsorption on pristine Single Walled Carbon
Nanotube (SWCNT) (8, 0) and Silicon doped Single walled Carbon Nanotube (Si . SWCNT)
by density functional theory calculations based on DeMol3 code. Importance is given to the
effects of silicon doping in carbon nanotube for comparative study of adsorption of ozone.
The results show that silicon doping keeps the semiconducting character of pure carbon
nanotubes with reduction in band gap from 0.71 eV to 0.54 eV. The ozone gas molecule is
physisorbed with binding energy 0.431eV and minute charge transfer of 0.013 e from pure
carbon nanotube, consistent with the strong oxidizing nature of ozone. The binding energy
and charge transfer indicate that the ozone adsorption on pure carbon nanotube is gentle and
reversible. However, when ozone adsorbs on silicon doped carbon nanotube, a strong
chemisorption occurs, leading to relevant structural relaxations and to the formation
of a Si-O σ bond with binding energy 3.902 eV and charge transfer of 0.252 e. The band
structure and density of states shows that the occupancy state in valence band near Fermi
energy is completely altered due to ozone adsorption. The charge density analysis also shows
formation of sigma bond between silicon and oxygen atoms. The charge density iso-surface
shows the oxidation of silicon atom and dissociation of ozone molecule into silicon - oxide
and releasing of oxygen molecule.
Keywords: CNT, Si-CNT, DFT, ozone, adsorption |
full paper (pdf, 992 Kb)