Silicon doping of defect sites in Stone–Wales defective carbon nanotubes: A density functional theory study

Abstract

Using density-functional theory calculations, we investigate how the stabilities and electronic properties of Stone Wales (SW) defective armchair (4,4) and (5,5) nanotubes are modified via Si atom doping at eight selected symmetric positions of SW defect sites with two different orientations, parallel and diagonal. A quasi-tetrahedral bonding configurations of silicon atoms based on sp3 hybridization are formed, which leads to puckered silicon doped rings. Our results indicate that tube diameter affects the doping reactions so that the doping single-walled carbon nanotubes (SWCNTs) with high curvature (small diameter) might be more favorable, based on both energetic and structural considerations. Density of state (DOS) obtained for the systems indicate that the doping of the defect sites causes the redistribution of electronic states of the SW defective SWCNTs. An average charge of 0.5e is also transferred from silicon atoms to first neighboring carbon atoms on the SWCNT, which indicates that charge redistributions after doping process mostly take place to a relatively small number of carbons at the zone of doped atoms.