Estudo teórico da interacção de oxigênio com nanotubos de BC2N

• Main Author: Rupp, Caroline Jaskulski
• Publication Date: 2011
• Format: Master thesis
• Language: por
• Source: Manancial - Repositório Digital da UFSM
• dARK ID: ark:/26339/00130000068xv
• Download full: http://repositorio.ufsm.br/handle/1/9217
• topic: Teoria do Funcional da Densidade; Nanotubos de BC2N; Oxig enio; Density functional theory; BC2N nanotubes; Oxygen; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA

Using first principles calculations based on the Density Functional Theory (DFT) with spin polarization and norm conserving fully separable pseudopotentials, we have studied the structural and electronic properties of the BC2N nanotubes and its interaction with oxygen atomic and molecular. The interaction with the atomic oxygen is investigated using substitutional and interstitial oxygen defects in type II BC2N nanotubes with two different chiralities: the armchair (3,3) and the zigzag (5,0). The interaction with the oxygen molecular is investigated by the adsorption of the O2 in the inner and outer surfaces of a type II armchair (3,3) BC2N nanotube. Our results show that the oxygen in the nitrogen site (ON) is the most favorable site for the substitutional oxygen defect and the electronic properties are similar for the two nanotubes, and shallow donor levels are observed. For the interstitial oxygen defects, the oxygen between the bond of boron and CI carbon (B-O-CI) is the most favorable site and electronic properties are only slightly modified compared with the pristine systems. For the interaction of oxygen molecular with a armchair (3,3) BC2N nanotube, the most stable configuration is obtained for the O2 molecule in the inner surface and perpendicular to the nanotube axis. This configuration is also more stable, considering the Van der Waals interactions between the nanotube and the O2 molecule in the calculation of binding energies. The electronic properties are not changed. We conclued that the interaction between the (3,3) nanotube and the O2 molecule is a phy-sical process, ruled by the Van der Waals interactions.