Ionic Transport in Electrostatic Janus Membranes. An Explicit Solvent Molecular Dynamic Simulation

Joan M. Montes De Oca, Johnson Dhanasekaran, Andrés Córdoba, Seth B. Darling, Juan J. De Pablo

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Janus, or two-sided, charged membranes offer promise as ionic current rectifiers. In such systems, pores consisting of two regions of opposite charge can be used to generate a current from a gradient in salinity. The efficiency of nanoscale Janus pores increases dramatically as their diameter becomes smaller. However, little is known about the underlying transport processes, particularly under experimentally accessible conditions. In this work, we examine the molecular basis for rectification in Janus nanopores using an applied electric field. Molecular simulations with explicit water and ions are used to examine the structure and dynamics of all molecular species in aqueous electrolyte solutions. For several macroscopic observables, the results of such simulations are consistent with experimental observations on asymmetric membranes. Our analysis reveals a number of previously unknown features, including a pronounced local reorientation of water molecules in the pores, and a segregation of ionic species that had not been anticipated by previously reported continuum analyses of Janus pores. Using these insights, a model is proposed for ionic current rectification in which electric leakage at the pore entrance controls net transport.

Original languageEnglish
Pages (from-to)3768-3775
Number of pages8
JournalACS Nano
Volume16
Issue number3
DOIs
StatePublished - Mar 22 2022
Externally publishedYes

Keywords

  • Janus membrane
  • ionic transport
  • nanofluidics
  • nonequilibrium molecular dynamics
  • power generation

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