Interactions of NOx (x = 1, 2, 3) with defective semiconducting (10,0) carbon nanotubes were studied using density functional theory. Optimized geometries, binding energies and electronic structures of the NOx-adsorbed nanotubes were determined on the basis of calculations. The effects of defect density and electric field on the binding energy and charge transfer were investigated. In sharp contrast with the case of a perfect nanotube, the adsorption of NOx at the defect site of (10,0) nanotubes was generally chemical. Following the chemisorption of one NO2 or one NO3, the carbon nanotubes with various defects behaved as conductors while the consecutive adsorption of the second NO2 or the second NO3 made these tubes become semiconductors again. Calculations showed that the NO2 adsorption at a topological defect was a barrier-free process, while the NO3 adsorption experienced a barrier due to transition of the π→s electronic configuration of the NO3 moiety.

Defect-Induced Chemisorption of Nitrogen Oxides on (10,0) Single-Walled Carbon Nanotubes: Insights from Density Functional Calculations. S.Tang, Z.Cao: Journal of Chemical Physics, 2009, 131[11], 114706