Designing Biomimic Two-Dimensional Ionic Transport Channels for Efficient Ion Sieving

Ion transport is crucial for biological systems and membrane-based technologies from both fundamental and practical aspects. Unlike biological ion channels, realizing efficient ion sieving by using membranes with artificial ion channels remains an extremely challenging task. Inspired by biological ion channels with proper steric containment of target ions within affinitive binding sites along the selective filter, herein we design a system of biomimic two-dimensional (2D) ionic transport channels based on a graphene oxide (GO) membrane, where the ionic imidazole group tunes the appropriate physical confinement of 2D ionic transport channels to mimic the confined cavity structures of the biological selectivity filter, and the ionic sulfonic group creates a favorable chemical environment of 2D ionic transport channels to mimic the affinitive binding sites of the biological selectivity filter. As a result, the as-fabricated ionic GO membrane demonstrates an exceptional K+ transport rate of similar to 1.36 mol m(-2) h(-1) and competitive K+/Mg2+ selectivity of similar to 9.11, outperforming state-of-the-art counterparts. Moreover, the semiquantitative studies of ion transport through 2D ionic transport channels suggest that efficient ion sieving with the ionic GO membrane is achieved by the high diffusion and partition coefficients of hydrated monovalent ions, as well as the large energy barrier and limited potential gradient of hydrated divalent ions encountered.

Automated summary

A biomimetic 2D ionic transport channel system based on graphene oxide (GO) membrane was designed, inspired by biological ion channels, showing exceptional K+ transport rate and competitive selectivity. The efficient ion sieving with the ionic GO membrane is achieved through high diffusion and partition coefficients of hydrated monovalent ions, as well as large energy barrier and limited potential gradient of hydrated divalent ions.