Intermediate-range solvent templating and counterion behaviour at charged carbon nanotube surfaces
Camilla Di Mino1,2, Thomas F Headen3, Nadir S Basma1,4
1Department of Physics and Astronomy, University College London, London, UK.
Nature Nanotechnology
|February 21, 2025
Summary
Charged carbon nanotubes create complex solvent ordering extending far beyond their surface. This ordering influences ion interactions and reveals multibody effects crucial for nanomaterial and electrochemical device applications.
Area of Science:
- Nanoscale science
- Physical chemistry
- Materials science
Background:
- Understanding ion and solvent ordering around nanostructures is vital for biological processes, nanomaterial manipulation, and electrochemical devices.
- Classical models often oversimplify solvent behavior due to experimental measurement challenges.
Purpose of the Study:
- To experimentally investigate the complex solvent ordering around charged carbon nanotubes.
- To challenge existing simplified models of solvation at the nanoscale.
Main Methods:
- Total neutron scattering experiments were conducted on concentrated amide solutions.
- Model systems included negatively charged carbon nanotubes with sodium counterions.
Main Results:
- Complex intermediate-range molecular solvent ordering was observed up to approximately 40 Å from the nanotube surface.
- Solvent molecules directly on the nanotube surface adopted a near-parallel orientation, distinct from those further away.
- Solvent ordering beyond the immediate layer was perpendicular to the surface, influenced by competing ion/surface solvation effects.
Conclusions:
- The study highlights the critical role of multibody interactions in solvated nanoscale systems.
- Experimental findings underscore the limitations of simplified models for charged surfaces and their solvation shells.
