Charge-induced electrochemical actuation of armchair carbon nanotube bundles

TL;DR

This study uses first-principles calculations to explore how charge doping induces structural and electronic changes in armchair carbon nanotube bundles, highlighting their potential for electromechanical actuation in artificial muscles.

Contribution

It demonstrates charge-induced deformation and electronic transitions in (6;6) SWNT bundles, providing insights for designing nanotube-based actuators.

Findings

Hole doping causes larger actuation responses than electron doping.

Charge doping can induce a semiconductor-to-metal transition.

The Young modulus increases at high electron doping levels.

Abstract

The effects of charge doping on the structural deformation and on the electronic structure of armchair single wall carbon nanotube (SWNT) bundles are investigated through first-principles calculations. In particular, we select a (6; 6) SWNT as an example and we calculate a mechanical deformation in the SWNT bundles as a function of gate voltage, which could serve as a basis of the electromechanical actuators in an artificial muscle. We find that the magnitudes of the actuation responses such as strain and stress of the (6; 6) SWNT bundle in the case of hole doping are substantially larger than those of electron doping. The (6; 6) SWNT bundle also exhibits a low-symmetry and opens an energy band gap of about 0.41 eV around the charge neutral condition, which allows a semiconductor-to-metal transition in the electron-doping regime when the relative shift of the Fermi energy goes up to 0.60 eV, above which the Young modulus increases.