Anomalous water transport in narrow-diameter carbon nanotubes

Zhengyi Wan, Yurui Gao, Xiangyu Chen, Xiao Cheng Zeng, Joseph S. Francisco, Chongqin Zhu

Research output: Contribution to journalArticlepeer-review

Abstract

Carbon nanotubes (CNTs) mimicking the structure of aquaporins support fast water transport, making them strong candidates for building next-generation highperformance membranes for water treatment. The diffusion and transport behavior of water through CNTs or nanoporous graphene can be fundamentally different from those of bulk water through a macroscopic tube. To date, the nanotube-length- dependent physical transport behavior of water is still largely unexplored. Herein, on the basis of molecular dynamics simulations, we show that the flow rate of water through 0.83-nm-diameter (6,6) and 0.96-nm-diameter (7,7) CNTs exhibits anomalous transport behavior, whereby the flow rate increases markedly first and then either slowly decreases or changes slightly as the CNT length l increases. The critical range of l for the flow-rate transition is 0.37 to 0.5 nm. This anomalous water transport behavior is attributed to the l-dependent mechanical stability of the transient hydrogen-bonding chain that connects water molecules inside and outside the CNTs and bypasses the CNT orifice. The results unveil a microscopic mechanism governing water transport through subnanometer tubes, which has important implications for nanofluidic manipulation.

Original languageEnglish (US)
Article numbere2211348119
JournalProceedings of the National Academy of Sciences of the United States of America
Volume119
Issue number39
DOIs
StatePublished - Sep 27 2022

Keywords

  • carbon nanotube
  • hydrogen bond
  • water flow

ASJC Scopus subject areas

  • General

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