Abstract—We report reactivity of silicon doped single walled carbon nanotube (Si–CNT) towards the small atmospheric gas molecules O2, CO2, SO2 and NO2 using density functional theory based on the numerical basis set method. The reactivity of gas molecules is explained with binding energy, band structure, charge density, and density of states. We found that the substitutional doping of silicon atom in CNT increases the binding energy as compared with pure CNT. The charge density analysis reveals the formation of sigma (σ) bonds between silicon and carbon atoms. Further, the band structure and density of states clearly illustrate the creation of extra state near the Fermi level and reduction in the band gap, which acts as a reactive center for adsorption of the molecules on Si–CNT. We have observed that the large value of adsorption energy shows the chemisorption between molecules and Si–CNT. Mulliken population analysis clearly reveals the charge-induced dipole interactions between the Si–CNT and molecules, which are responsible for chemisorption for gas molecules. The donor like impurity state generated in energy gap almost disappears after adsorption of all gas molecules excluding NO2. We further note that molecules accept the electronic charge from nanotubes and have significant influence on electronic structure near the Fermi level and are responsible for the increase in the p-type conductivity of tubes.

Index Terms—Density Functional Theory, Gas Molecules, Interaction, Si–CNT.

M. R. Sonawane is with the Department of Physics, University of Mumbai, Kalina, Santacruz (E), Mumbai-400098, (India). (E-mail:smahadev123@gmail.com).
Darshan Habale is with the Department of Physics, University of Mumbai, Kalina, Santacruz (E), Mumbai-400098, (India). (E-mail:darshanhabale@gmail.com).
B. J. Nagare is from 13/002 Om Laxmi Narayan C.H.S. Nebula Darshan, Wayle Nagar, Kalyan, Thane-421301, (India) (E-mail:bjnagare@gmail.com).
Rita Gharde is with the Department of Physics, University of Mumbai, Kalina, Santacruz (E), Mumbai-400098, (India).

Cite: M. R. Sonawane, Darshan Habale, B. J. Nagare, and Rita Gharde, "Interaction of O₂, CO₂, NO₂ and SO₂ on Si- doped Carbon Nanotube," International Journal of Applied Physics and Mathematics  vol. 1, no. 2, pp. 138-143, 2011.