Effects of hydrogen adsorption on single wall carbon nanotubes: Metallic hydrogen decoration

TL;DR

This study uses first-principles calculations to show that hydrogen chemisorption dramatically alters the electronic and atomic structure of carbon nanotubes, inducing metallic or insulating states depending on the hydrogenation pattern.

Contribution

It provides new insights into how hydrogen adsorption modifies nanotube structures and electronic properties, highlighting stable isomers with distinct conductive behaviors.

Findings

Half-coverage exohydrogenation makes zigzag nanotubes square or rectangular and metallic.

Alternating inside-outside hydrogenation yields stable isomers with large band gaps.

Hydrogenation effects show weak curvature dependence.

Abstract

We show that the electronic and atomic structure of carbon nanotubes undergo dramatic changes with hydrogen chemisorption from first principle calculations. Upon uniform exohydrogenation at half coverage, the cross sections of zigzag nanotubes become literally square or rectangular, and they are metallic with very high density of states at the Fermi level, while other isomers can be insulating. For both zigzag and armchair nanotubes, hydrogenation of each carbon atom from inside and outside alternatively yield the most stable isomer with a very weak curvature dependence and a large band gap.