Fast Water Channeling across Carbon Nanotubes in Far Infrared Terahertz Electric Fields

TL;DR

This study uses molecular dynamics simulations to reveal how terahertz electric fields can significantly enhance water flow through carbon nanotubes by resonating with water molecule motions, with potential for high-flux device applications.

Contribution

It demonstrates the resonant enhancement of water permeation in carbon nanotubes under terahertz electric fields, highlighting the role of molecular responses and field orientation.

Findings

Peak water flux enhancement at around 14 THz with TEF normal to nanotube

Suppression of flux enhancement when TEF is aligned along the nanotube axis

Resonant water molecule responses involve librational, rotational, and rotation-induced motions

Abstract

Using molecular dynamics simulations, we investigate systematically the water permeation properties across the single-walled carbon nanotube (SWCNT) in the presence of the terahertz electric field (TEF). With the TEF normal to the nanotube, the fracture of the hydrogen bonds results in the giant peak of net fluxes across the SWCNT with a three-fold enhancement centered around 14THz. The phenomenon is attributed to the resonant mechanisms, characterized by librational, rotational, and rotation-induced responses of in-tube polar water molecules to the TEF. For the TEF along the symmetry axis of the nanotube, the vortical modes for resonances and consequently the enhancement of net fluxes are greatly suppressed by the alignment of polar water along the symmetry axis, which characterizes the quasi one-dimensional feature of the SWCNT nicely. The resonances of water molecules in the TEF can have potential applications in the high-flux device designs used for various purposes.