Biomimetic Nacre‐Inspired Nanofluidic Membranes with Concurrently Enhanced Ionic Conductivity and Mechanical Robustness

ABSTRACT Two‐dimensional nanofluidic membranes are emerging as attractive functional materials for osmotic energy conversion, yet their practical implementation is hindered by the intrinsic trade‐off between ionic conductivity and mechanical robustness. Here, inspired by the hierarchical brick‐and‐mortar architecture of nacre and amino‐acid‐regulated ion transport in biological channels, a biomimetic hybrid nanofluidic membrane is developed by integrating glycine‐grafted poly(vinyl alcohol) (PVA_Gly) into natural vermiculite via a simple vacuum‐assisted infiltration process. The grafted polymer simultaneously reinforces interlayer interactions and constructs bio‐inspired ion‐transport pathways while preserving the ordered lamellar framework. Consequently, the composite membrane achieves a nearly threefold enhancement in ionic conductivity together with a ∼3.5‐fold increase in tensile strength, effectively breaking the conventional conductivity–mechanical trade‐off. The universality of this biomimetic hybridization strategy is further demonstrated in graphene oxide– and MXene‐based nanofluidic membranes, which exhibit concurrent improvements in ion transport and mechanical performance. When applied to osmotic energy harvesting, the optimized membranes deliver a high power density of 18.8 W m −2 under parallel ion transport, exceeding most reported two‐dimensional nanofluidic membranes and surpassing the commonly cited commercialization benchmark. This work establishes a scalable biomimetic materials design strategy for constructing mechanically robust, high‐performance nanofluidic membranes, offering new opportunities for advanced energy‐conversion applications.