Crystal orbital study on the double walls made of nanotubes encapsulated inside zigzag carbon nanotubes

•The structure and electronic properties of the 1D n-gon SiO2@(m,0)s are studied using SCF-CO method.•The encapsulation of 1D n-gon SiO2 tubes inside zigzag carbon nanotubes can be energetically favorable.•The 1D n-gon SiO2@(m,0)s are all semiconductors.•The mobility of charge carriers and Young’s moduli are calculated.

The structure stabilities and electronic properties are investigated by using ab initio self-consistent-field crystal orbital method based on density functional theory for the one-dimensional (1D) double-wall nanotubes made of n-gon SiO2 nanotubes encapsulated inside zigzag carbon nanotubes. It is found that formation of the combined systems is energetically favorable when the distance between the two constituents is around the Van der Waals scope. The obtained band structures show that all the combined systems are semiconductors with nonzero energy gaps. The frontier energy bands (the highest occupied band and the lowest unoccupied band) of double-wall nanotubes are mainly derived from the corresponding carbon nanotubes. The mobilities of charge carriers are calculated to be within the range of 102–104 cm2 V−1 s−1 for the hybrid double-wall nanotubes. Young’s moduli are also calculated for the combined systems. For the comparison, geometrical and electronic properties of n-gon SiO2 nanotubes are also calculated and discussed.

Graphical abstractStructures and band structures of the optimum 1D Double walls nanotubes. The optimized structures are 3-gon SiO2@(15,0), 5-gon SiO2@(17,0), 6-gon SiO2@(18,0) and 7-gon SiO2@(19,0).Figure optionsDownload full-size imageDownload as PowerPoint slide