Diffusion behavior of water confined in deformed carbon nanotubes

TL;DR

This study uses molecular dynamics simulations to explore how deformation of carbon nanotubes affects water diffusion, revealing structural transitions and mobility changes linked to nanotube shape alterations.

Contribution

It demonstrates how nanotube deformation influences water's structural phase and diffusion behavior, highlighting the importance of shape in confined water dynamics.

Findings

Water transitions from tubular-like to single-file structure with deformation.

Deformation induces a shift from frozen to liquid water inside nanotubes.

Diffusion enhancement or suppression correlates with hydrogen bond changes.

Abstract

We use molecular dynamics simulations to study the diffusion of water inside deformed carbon nanotubes, with different degrees of eccentricity at 300K. We found a water structural transition between tubular-like to single-file for the (7,7) nanotubes associated with a change from a high to low mobility regimes. The water which in the undeformed (9,9) nanotubes is frozen, becomes liquid for the distortion above a certain threshold. These water diffusion enhancement (suppresion) is related to a reduction (increase) in the number of hydrogen bonds. This suggests that the shape of the nanotube is a particularly important ingredient when considering the dynamical and structural properties of confined water.