4.8 Article

Diameter Dependence of Water Filling in Lithographically Segmented Isolated Carbon Nanotubes

Journal

ACS NANO
Volume 15, Issue 2, Pages 2778-2790

Publisher

AMER CHEMICAL SOC
DOI: 10.1021/acsnano.0c08634

Keywords

carbon nanotubes; nanofluidics; nanopore; Raman spectroscopy; confinement effects; slip flow

Funding

  1. Center for Enhanced Nanofluidic Transport (CENT), an Energy Frontier Research Center - U.S. Department of Energy, Office of Science, Basic Energy Sciences [DE-SC0019112]
  2. National Science Foundation [1122374]
  3. German Research Foundation (DFG) [KU 3952/1-1]
  4. National Science Foundation under NSF [ECS-0335765]

Ask authors/readers for more resources

Researchers utilized an experimental platform based on single-walled carbon nanotubes to study water under extreme nanoscale confinement. The changes in Raman radial breathing mode were shown to reflect the increase in interior mechanical modulus caused by liquid water filling under restricted conditions, with diameter-dependent patterns observed.
Although the structure and properties of water under conditions of extreme confinement are fundamentally important for a variety of applications, they remain poorly understood, especially for dimensions less than 2 nm. This problem is confounded by the difficulty in controlling surface roughness and dimensionality in fabricated nanochannels, contributing to a dearth of experimental platforms capable of carrying out the necessary precision measurements. In this work, we utilize an experimental platform based on the interior of lithographically segmented, isolated single-walled carbon nanotubes to study water under extreme nanoscale confinement. This platform generates multiple copies of nanotubes with identical chirality, of diameters from 0.8 to 2.5 nm and lengths spanning 6 to 160 mu m, that can be studied individually in real time before and after opening, exposure to water, and subsequent water filling. We demonstrate that, under controlled conditions, the diameter-dependent blue shift of the Raman radial breathing mode (RBM) between 1 and 8 cm(-1) measures an increase in the interior mechanical modulus associated with liquid water filling, with no response from exterior water exposure. The observed RBM shift with filling demonstrates a non-monotonic trend with diameter, supporting the assignment of a minimum of 1.81 +/- 0.09 cm(-1) at 0.93 +/- 0.08 nm with a nearly linear increase at larger diameters. We find that a simple hard-sphere model of water in the confined nanotube interior describes key features of the diameter-dependent modulus change of the carbon nanotube and supports previous observations in the literature. Longer segments of 160 mu m show partial filling from their ends, consistent with pore clogging. These devices provide an opportunity to study fluid behavior under extreme confinement with high precision and repeatability.

Authors

I am an author on this paper
Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.8
Not enough ratings

Secondary Ratings

Novelty
-
Significance
-
Scientific rigor
-
Rate this paper

Recommended

No Data Available
No Data Available