Harnessing Entropic Effects from Interlayer Coupling to Modulate Ion Transport and Rectification in Multilayered...

Ion transport through nanoscale channels enables advanced functionalities, such as ionic current rectification (ICR), with promising applications in neuromorphic computing and biomimetic signal processing. However, the fundamental mechanisms controlling the ion dynamics under nanoconfinement remain poorly understood. Using atomistic molecular dynamics simulations and free energy calculations, we demonstrate that multilayered Janus graphene oxide nanopores exhibit exceptional and tunable ICR performance mediated by interlayer coupling. These structures achieve a rectification ratio enhancement of up to 2 orders of magnitude─from ∼2 in a single layer to over 2000 at 3.5 V/nm in multilayered configurations─and a shift of the peak rectification field from 0.7 to 3.5 V/nm with increasing layer number. Ion distribution analyses reveal distinctive ionic enrichment-depletion behavior unique to multilayered architectures. Thermodynamically, we unveil that synergistic interlayer coupling fundamentally reshapes the free energy landscape, creating a highly asymmetric profile with multiple energy barriers and wells due to entropy─enthalpy competition. Importantly, entropy is identified to play a critical role in stabilizing energy wells and facilitating directional ion transport─a mechanism absent in single-layer systems. These insights provide a mechanistic basis for ion rectification and establish design principles, such as interlayer spacing or number control, for developing high-performance ionic membranes and nanofluidic devices.