Coupled transport of water and ions in intercalated graphene nanochannels

Understanding the coupled transport of water and ions under nanoscale confinement is essential for advancing nanofluidic applications. In this work, we employed molecular dynamics simulations to investigate the electrohydrodynamic transport behavior of aqueous NaCl solution within graphene nanochannels containing an intercalated graphene layer. The results show that in a narrow channel, the intercalated layer induces strong confinement effects, leading to complete suppression of anion migration and nearly 100% unidirectional water transport, resembling the function of biological nanoscale pumps. This geometry-induced directional transport suggests a feasible strategy for designing solid-state nanofluidic pumps or ion-rectifying elements. Furthermore, both ion and water fluxes increase nearly linearly with field strength, while ion translocation times follow a power-law relationship (τ∼E^-1), consistent with the one-dimensional Langevin model. Such predictable field-dependent responses highlight the potential of intercalated graphene nanochannels as electrically programmable nanofluidic components. The hydration numbers of ions remain nearly constant, suggesting that the enhanced transport originates from dynamic acceleration rather than structural rearrangement. Overall, this study provides microscopic insights into the interplay between confinement geometry and water-ion coupling, and offers theoretical guidance for the rational design of graphene-based nanochannels for controllable molecular transport, selective separation, and functional nanofluidic device application.