The Theoretical Study of Interaction CO Gas with Pristine and As N doped AlNNTs

Carbon monoxide molecule is highly toxic to human beings and animals as they inhibit the consumption of oxygen by body tissues. CO gas is colourless, odourless, and tasteless, and thus, human beings do not have timely alertness to their presence. Therefore, gas sensors with high sensitivity to this gas are highly desired. Many efforts have been made to reduce and monitoring the amount of carbon monoxide [1-3]. In the present project we study the effects of adsorption CO molecule and As-doped on the electrical and optical properties of AlNNTs at various configurations. From optimized structures, the adsorption energy, HOMO-LUMO orbital and other quantum molecular descriptors: electronic chemical potential (μ), global hardness (η), electrophilicity index (ω), energy gap (Egap), global softness (S), and electronegativity (χ) of the nanotubes are calculated by using DFT theory. The results indicate that the adsorption energy of all models is negative and is favourable in view of thermodynamic approach. The result show that the Fermi level energy of whole models is close to HOMO energy, it is probably the most important factor in determining the current and the direction of natural flow of electrons. The results demonstrate that AS doping decrease the sensivity of AlNNTs to adsorb of CO gas (see Fig 1). The electrophilicity index (ω) determines maximum flow of electron from donor to acceptor species and supplies data connected to structural stability, reactivity and toxicity of chemisorbed on the surface of nanotube, a fairly large charge transfer occurs between two related species, thus their electronic transport properties could be significantly changed upon physisorption of CO. The results show that the electrophilicity index in (b, g) models of As-doped increase from 2.18 to 3.36 and 1.84 to 3.36 eV respectively, and on the other models decrease.