Electron-electrolyte coupling in AC transport through nanofluidic channels

TL;DR

This paper explores how AC-driven nanofluidic channels exhibit complex ionic and electronic transport behaviors, revealing new interfacial phenomena and potential for device engineering.

Contribution

It introduces a frequency-dependent transport matrix capturing ionic, electronic, and hydrodynamic couplings in AC nanofluidic systems, highlighting electron-electrolyte interactions.

Findings

Identification of a critical frequency where electron conduction dominates

Demonstration of how electron-ion coupling alters electro-osmotic flows

Revelation of distinct AC signatures depending on charge carrier polarity

Abstract

The transport properties of nanofluidic channels are usually studied under constant (DC) voltage or pressure driving. However, the frequency response under sinusoidal (AC) drivings offers rich insights into the time-dependent transport mechanisms. Inspired by recent electrochemical approaches, we investigate the couplings between ionic and electronic transport under AC driving. We show that conduction electrons of the channel walls participate in ionic current via capacitive electrochemical coupling, defining a critical frequency and length scale where electron-dominated conductivity emerges. We further analyze how electron-ion coupling modifies electro-osmotic flows, and demonstrate that fluctuation-induced momentum transfer between the electrolyte and wall electrons produces distinct AC transport signatures depending on the charge carrier polarity. Altogether, we establish a frequency-dependent transport matrix that couples ionic, electronic and hydrodynamic flows. These findings establish AC nanofluidic transport as a powerful probe of interfacial phenomena under confinement, and suggest new directions for engineering nanofluidic functionalities through electron-electrolyte coupling.