Water diffusion in carbon nanotubes: interplay between confinement, surface deformation and temperature

TL;DR

This study uses molecular dynamics simulations to explore how confinement, surface deformation, and temperature affect water diffusion in carbon nanotubes, revealing a transition from non-Arrhenius to Arrhenius behavior influenced by nanotube size and deformation.

Contribution

It provides new insights into the diffusion mechanisms of water in deformed and pristine carbon nanotubes across a range of temperatures, highlighting the effects of confinement and surface deformation.

Findings

Water diffusion exhibits a non-Arrhenius to Arrhenius crossover.

Confinement shifts the diffusion transition to higher temperatures.

Narrow nanotubes enable single-file water diffusion with mobility independent of activation energy.

Abstract

In this article we investigate through molecular dynamics simulations the diffusion behavior of the TIP4P/2005 water when confined in pristine and deformed carbon nanotubes (armchair and zigzag). To analyze different diffusive mechanisms, the water temperature was varied from $210\leq T\leq 380$~K. The results of our simulations reveal that water present a non-Arrhenius to Arrhenius diffusion crossover. The confinement shifts the diffusion transition to higher temperatures when compared with the bulk system. In addition, for narrower nanotubes, water diffuses in a single line which leads to a mobility independent of the activation energy.