الفهرس | Only 14 pages are availabe for public view |
Abstract This thesis represents a theoretical study for pure carbon nanotubes (CNTs), pure boron nitride nanotubes (BNNTs), and carbon boron nitride nanotubes heterojunction (CBNNTs), to investigate their effect of tubular chiralities and diameters on gas sensing behavior for CO, CO2, NO and NO2 gas molecules. The thesis consists of six chapters, general conclusion and a list of references. In chapter I, brief report on carbon, CNTs, BNNT and CBNTs, in addition to their structures and physical properties are investigated. In chapter II, short theoretical background about the basic molecular electronic structure methods, Hartree-Fock (HF) and density functional theory (DFT) is illustrated. Furthermore, Gaussian 03 and Gaussian View 4.1 program package which have been used in this thesis are discussed. In chapter III, a literature review is given about the available NTs gas sensors of some pollutant gas molecules, especially for CNTs, BNNTs, and CBNNTs gas sensors. In chapter IV, The effect of tubular chiralities and diameters of CNTs on gas sensing behavior is investigated. In this chapter, the density functional theory is applied to obtain the geometric and electronic structures, the surface reactivity and the formation energies of adsorption CO, CO2, NO and NO2 gas molecules on zigzag and armchair CNTs. Then, the best CNT gas sensor is selected. In chapter V, the adsorption of CO, CO2, NO and NO2 gas molecules on the zigzag and armchair BNNTs using DFT is studied. The geometric and electronic structures, the surface reactivity and the formation energies of adsorption CO, CO2, NO and NO2 gas molecules on zigzag and Summary xvii armchair BNNTs with different diameters are investigated. Then, the best BNNT gas sensor is selected. In chapter VI, the adsorption of CO, CO2, NO and NO2 on zigzag and armchair CBNNTs is reported. The geometric and electronic structures, the surface reactivity and the formation energies of adsorption CO, CO2, NO and NO2 gas molecules on zigzag and armchair CBNNTs with different diameters are obtained. Then, the best CBNNT gas sensor is selected. The thesis includes also general conclusions for the studied parts. |