A computational study on the interaction between O$_{2}$ and pristine and Ge-doped aluminum phosphide nanotubes

Abstract

In this research the interaction between oxygen molecules and the outside and inside surfaces of pristine and Ge-doped (4,4) armchair and (6,0) zigzag models of aluminum phosphide nanotubes (AlPNTs) was systematically investigated using density function theory. Structural parameters, adsorption energy, quantum parameters, HOMO/LUMO orbitals, and nuclear quadrupole resonance (NQR) parameters were calculated for all models of AlPNTs. The aim of this work was to investigate the effects of Ge doping and O$_{2}$ adsorption on the electrical and structural parameters of (4,4) armchair and (8,0) zigzag models of AlPNTs. The results revealed that adsorption energies for all models were negative with exothermic chemical bonding. By doping Ge in spite of the B52 site of (4,4) armchair and (6,0) zigzag models the adsorption energy increased significantly from pristine values and therefore Ge doping increased the reactivity of the nanotubes to O$_{2}$ adsorption. The NQR results showed that in AlPNTs Al atoms at the edges of nanotubes played a significant role in determining the electronic behaviors of AlPNTs and the average values of C$_{Q}$ ($^{27}$Al) and $\eta_{Q}$ for the O$_{2}$ attached on (4,4) armchair and (6,0) zigzag AlPNTs were higher than those of the pristine model. Analysis of the electronic properties indicated that adsorption of O$_{2}$ reduced the energy gap of AlPNTs. Quantum molecular results showed that the global hardness ($\eta )$ of Ge-doped models was smaller than that of other models.