Spatially directed synthesis of charge‐ and wettability‐asymmetric layers for selective anion transport

Abstract The development of monovalent‐selective anion exchange membranes is critical for advanced separation processes, yet overcoming the permeability‐selectivity trade‐off remains a persistent challenge. In this work, we propose a spatially directed synthesis strategy to construct nanoscale heterogeneous interfaces. By coupling electrophoretic deposition of an electronegative inner template with site‐specific Fe 3+ coordination, the interfacial polymerization was regulated to form a compact, hydrophobic outer shell. This structural design integrates distinct transport‐governing functions within a single interface. The resulting membrane achieved a Cl − /SO 4 2− selectivity of 17.04 with a Cl − flux of 0.3856 mmol·m −2 ·s −1 . Experimental characterization combined with molecular dynamics simulations suggested that the enhanced permselectivity can be attributed to the synergistic effects of Donnan exclusion from the electronegative inner layer and the increased dehydration penalty and spatial confinement imposed by the hydrophobic outer layer on multivalent anions. This work provides a practical interfacial design strategy for developing multilayered membranes with regulated ion transport behavior.