Electronic Transport Properties of Chemically Modified Double-Walled Carbon Nanotubes

TL;DR

This study investigates how chemical modifications, such as defects and functional groups, influence the electronic transport properties of double-walled carbon nanotubes, revealing ways to tailor their conductivity for nanotechnology applications.

Contribution

It provides first-principles insights into how chemical functionalization affects charge transport in double-walled carbon nanotubes, highlighting conditions for maintaining or reducing conductivity.

Findings

Outer wall defects reduce overall charge transport.

Increased functional group coverage decreases outer wall conductivity.

Inner tube transport remains unaffected with certain modifications.

Abstract

We present a study on the quantum transport properties of chemically functionalized metallic double-walled carbon nanotubes (DWNTs) with lengths reaching the micrometer scale. First-principles calculations evidence that, for coaxial tubes separated by the typical graphitic van der Waals-bond distance, the chemical modification of the outer wall with sp$^3$-type defects affects the electronic structure of both the outer and the inner tube, which reduces significantly the charge transport capability of the DWNT. For larger spacing between sidewalls, the conductivity of the outer wall decreases with increasing functional group coverage density while charge transport in the inner tube is equivalent to that of a pristine nanotube. Additionally, chemical attachment of CCl$_2$ onto the outer DWNT sidewall barely affect the conjugated $\pi$-network of the double-wall and charge transport remains in the quasi-ballistic regime. These results indicate an efficient route for tailoring electronic transport in DWNTs provided inner shell geometry and functional groups are properly chosen.