Voltage-Gated Ion Transport in Two-Dimensional Sub-1 nm Nanofluidic Channels

Abstract

Voltage-gated nanofluidic systems have shown a wide range of potential applications in biosensors, energy harvest, and separation. Two-dimensional (2D) nanofluidic membranes fabricated with electrically conductive nanosheets have high ion conductivity and voltagegated ion transport behaviors. However, the voltage-gating effect of the sub-nanometer-sized 2D channel membranes has not been well-investigated. In this work, a highperformance voltage-gated 2D nanofluidic device is constructed by assembling MXene nanosheets into a laminar membrane with sub-1 nm interlayer channels. By applying external voltage to the membrane, the ion conductivity of the device is enhanced by positive voltages and reduced by negative voltages, exhibiting a high voltagegating on−off ratio of ∼10. The on−off ratio is found to be dependent on ion concentration and ion species. This work demonstrates that 2D membranes with interlayer spacings comparable to those of hydrated ion diameters can achieve high and tunable voltage-gating function, which provides a strategy to construct devices for highly efficient on-demand ion transport.

Harnessing Ionic Power from Equilibrium Electrolyte Solution via Photoinduced Active Ion Transport through van‐der‐Waals‐Like Heterostructures

“…[ 8 ] These macroscopic 2D‐material‐based membranes contain massive nanometer‐ or even sub‐nanometer‐height ionic/fluidic channels, [ 9–12 ] and thus provide a unique platform for understanding the novel transport phenomena under confinement and a variety of ionics‐related applications, [ 13 ] such as precise ionic sieving, [ 14,15 ] ionic power generation and storage, [ 16,17 ] and other biomimetic ionic devices. [ 18,19 ]…”

“…[8] These macroscopic 2D-material-based membranes contain massive nanometer-or even sub-nanometer-height ionic/fluidic channels, [9][10][11][12] and thus provide a unique platform for understanding the novel transport phenomena under confinement and a variety of ionics-related applications, [13] such as precise ionic sieving, [14,15] ionic power generation and storage, [16,17] and other biomimetic ionic devices. [18,19] Generally, there are three types of driving force for ion transport, that is, the electric field, the mechanical pressure, and the concentration gradient. [20] In the recent years, light is newly proposed as the fourth type of driving force for remote, noninvasive, and active control of molecular and ionic transport in manmade materials.…”

MXene‐Based Membranes for Separation Applications

“…Reproduced with permission. [ 67 ] Copyright 2019, American Chemical Society. c) Scheme of the Ti 3 C 2 T x membrane‐based osmotic energy generator.…”

Electrohydrodynamic and Hydroelectric Effects at the Water–Solid Interface: from Fundamentals to Applications

“…[ 44 ] Therefore, this unique control of ion flow by applying a voltage was thereby proposed as a nanofluidic field‐effect transistor. [ 38,58,59 ] Besides nanofluidic diode and nanofluidic field‐effect transistor, these electrically induced nanofluidic have also shown many discovered results beyond the traditional knowledge, and thus the study of these kinds of flow will lead to better optimization of existing related technologies.…”