Jump to main content
Jump to site search

Issue 14, 2013

Anisotropy of the water–carbon interaction: molecular simulations of water in low-diameter carbon nanotubes

Author affiliations

Abstract

Effective Lennard-Jones models for the water–carbon interaction are derived from existing high-level ab initio calculations of water adsorbed on graphene models. The resulting potential energy well (εCO + 2εCH ≈ 1 kJ mol−1) is deeper than most of the previously used values in the literature on water in carbon nanotubes (CNTs). Moreover, a substantial anisotropy of the water–carbon interaction (εCO ≈ 2εCH) is obtained, which is neglected in most of the literature. We systematically investigate the effect of this anisotropy on structure and dynamics of TIP5P water confined in narrow, single-walled CNTs by means of molecular dynamics simulations for T = 300 K. While for isotropic models water usually forms one-dimensional, ordered chains inside (6,6) CNTs, we find frequent chain ruptures in simulations with medium to strongly anisotropic potentials. Here, the water molecules tend to form denser clusters displaying a liquid-like behaviour, allowing for self-diffusion along the CNT axis, in contrast to all previous simulations employing spherical (εCH = 0) interaction models. For (7,7) CNTs we observe structures close to trigonal, helical ice nanotubes which exhibit a non-monotonous dependence on the anisotropy of the water–carbon interaction. Both for vanishing and for large values of εCH we find increased fluctuations leading to a more liquid-like behaviour, with enhanced axial diffusion. In contrast, structure and dynamics of water inside (8,8) CNTs are found to be almost independent of the anisotropy of the underlying potential, which is attributed to the higher stability of the non-helical fivefold water prisms. We predict this situation to also prevail for larger CNTs, as the influence of the water–water interaction dominates over that of the water–carbon interaction.

Graphical abstract: Anisotropy of the water–carbon interaction: molecular simulations of water in low-diameter carbon nanotubes

Article information


Submitted
29 Nov 2012
Accepted
01 Feb 2013
First published
04 Feb 2013

Phys. Chem. Chem. Phys., 2013,15, 4995-5006
Article type
Paper

Anisotropy of the water–carbon interaction: molecular simulations of water in low-diameter carbon nanotubes

G. Pérez-Hernández and B. Schmidt, Phys. Chem. Chem. Phys., 2013, 15, 4995 DOI: 10.1039/C3CP44278K

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.


Social activity

Search articles by author

Spotlight

Advertisements