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Ion Transport in Electrically Imperfect Nanopores
Yechan Noh1, Narayana R Aluru1
1Department of Mechanical Science and Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
ACS Nano
|August 19, 2020
Summary
Surface conductance in charged nanopores depends on ion concentration. This study reveals that nanopore "imperfectness" explains varying power-law exponents observed in experiments, offering a new theory for ionic transport.
Area of Science:
- Nanoscale science
- Physical chemistry
- Computational physics
Background:
- Ionic transport in charged nanopores is crucial for various applications.
- Surface conductance dominates ionic transport at low concentrations.
- Existing models struggle to explain experimental variations in surface conductance power-law exponents (α).
Purpose of the Study:
- To investigate the physical origin of varying power-law exponents in surface conductance.
- To develop a theoretical framework for ionic transport in electrically imperfect nanopores.
- To reconcile simulation results with experimental observations.
Main Methods:
- Extensive coarse-grained Molecular Dynamics simulations.
- Systematic variation of nanopore diameter, length, and surface charge density.
- Development of a new ionic conductance theory for imperfect nanopores.
Main Results:
- Observed varying power-law exponents (α) even with constant surface charge.
- Demonstrated that nanopore electrical "imperfectness" (charge imbalance) dictates α.
- Identified a correlation between the degree of imperfectness and the exponent value.
Conclusions:
- Nanopore electrical imperfectness is the key to understanding variable surface conductance power-law exponents.
- The proposed theory successfully explains experimental data and simulation findings.
- Provides a unified framework for ionic transport in charged nanopores.
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