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Modulating multivalent ion interaction in angstrom-scale confinement through solvent environment
Xiaolin Yue1, Mingzhan Wang1,2, Dongchen Ying1
1Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA. chongliu@uchicago.edu.
Faraday Discussions
|April 23, 2026
Summary
Solvent composition controls ion behavior in angstrom-scale nanochannels. Tuning solvent mixtures enables selective rare-earth element (REE) separation by influencing ion uptake and dynamics.
Area of Science:
- Materials Science
- Nanotechnology
- Physical Chemistry
Background:
- Ion-solvent interactions become complex at the angstrom-scale (Å-scale) due to water's unique properties.
- Understanding solvent effects on ion behavior in confined environments is crucial but largely unexplored.
- Functionalized two-dimensional (2D) materials offer a platform to study these Å-scale phenomena.
Purpose of the Study:
- To investigate how solvent environment regulates ion dynamics, uptake, and selectivity in Å-scale nanochannels.
- To use rare-earth elements (REEs) as a model system to probe solvent-mediated ion separation.
- To elucidate the mechanisms behind solvent-controlled ion behavior in 2D nanochannels.
Main Methods:
- Utilized functionalized two-dimensional molybdenum disulfide (2D MoS2) nanochannels.
- Systematically tuned solvent composition to observe effects on ion behavior.
- Employed dynamic tests and analyzed binding-site deprotonation and dielectric effects.
Main Results:
- Ion uptake and selectivity are governed by solvent-dependent acidity and dielectric properties.
- Maximum ion uptake occurred at intermediate solvent ratios balancing acidity and dielectric effects.
- Dimethylformamide-rich systems showed shifted selectivity towards heavier REEs due to increased deprotonation.
Conclusions:
- Solvent composition is a critical factor for tuning ion behavior and separation in 2D nanochannels.
- Mechanistic insights into solvent-mediated selective REE recovery and separation were provided.
- Findings offer a pathway for designing advanced separation technologies based on solvent engineering.
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