Structures of water molecules in carbon nanotubes under electric fields

Winarto, Daisuke Takaiwa, Eiji Yamamoto, Kenji Yasuoka

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Carbon nanotubes (CNTs) are promising for water transport through membranes and for use as nanopumps. The development of CNT-based nanofluidic devices, however, requires a better understanding of the properties of water molecules in CNTs because they can be very different from those in the bulk. Using all-atom molecular dynamics simulations, we investigate the effect of axial electric fields on the structure of water molecules in CNTs having diameters ranging from (7,7) to (10,10). The water dipole moments were aligned parallel to the electric field, which increases the density of water inside the CNTs and forms ordered ice-like structures. The electric field induces the transition from liquid to ice nanotubes in a wide range of CNT diameters. Moreover, we found an increase in the lifetime of hydrogen bonds for water structures in the CNTs. Fast librational motion breaks some hydrogen bonds, but the molecular pairs do not separate and the hydrogen bonds reform. Thus, hydrogen bonds maintain the water structure in the CNTs, and the water molecules move collectively, decreasing the axial diffusion coefficient and permeation rate.

Original languageEnglish
Article number124701
JournalJournal of Chemical Physics
Volume142
Issue number12
DOIs
Publication statusPublished - 2015 Mar 28

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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