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Probing the Structure and Dynamics of Interfacial Water with Scanning Tunneling Microscopy and Spectroscopy
Published on: May 27, 2018
3D Electron Microscopy Reveals Evidence for Strong Electric Fields at Nanoconfined Air-Water Interfaces
Ryota Saito1, Haruka Tsuruda1, Chenghui Zhu2
1Department of Aeronautics and Astronautics, Kyushu University, 744 Motooka, Fukuoka819-0395, Japan.
Journal of the American Chemical Society
|July 14, 2026
Summary
Researchers provide direct evidence for strong electric fields at air-water interfaces using carbon nanotubes. These intense fields, measured in volts per nanometer, drive nanoscale interfacial chemistry, impacting various systems.
Area of Science:
- Physical Chemistry
- Materials Science
- Nanotechnology
Background:
- Air-water interfaces are crucial in many chemical processes.
- Strong electric fields are hypothesized to accelerate interfacial chemistry.
- Direct evidence for these fields under controlled conditions is lacking.
Purpose of the Study:
- To provide direct, probe-free evidence of strong electric fields at air-water interfaces.
- To investigate the role of these fields in interfacial chemistry.
- To quantify the repulsive pressures at nanoscale interfaces.
Main Methods:
- Confining aqueous solutions and air within multiwalled carbon nanotubes (MWCNTs).
- Utilizing three-dimensional transmission electron microscopy (3D-TEM) for nanoscale imaging.
- Analyzing reconstructed multiphase structures and curvature for pressure calculations.
Main Results:
- Stabilized nanoscale air-water interfaces within ~50 nm diameter MWCNTs.
- Identified ~10 nm gas domains separated by ultrathin water films.
- Quantified a repulsive pressure of ~10 MPa, consistent with electric fields of several V/nm.
- Observed localized reduction of chloroauric acid to gold nanoparticles within ~2 nm of the interface.
Conclusions:
- Direct evidence for intense, spatially confined electric fields at air-water interfaces was obtained.
- These fields, driven by water dipoles and electric double layers, play a fundamental role in nanoscale interfacial chemistry.
- The findings have implications for chemical, environmental, and energy-relevant systems.
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