Two-Dimensional Nanofluidic Membranes with Nepenthes-Inspired Superstructures toward Boosting Solar-Driven Ionic Power Generation

Photoinduced transmembrane ion transport in organisms provides a distinctive perspective for exploiting the ocean enriched with both ions and solar energy. Artificial two-dimensional nanofluidic membranes for photothermal-driven ion transport are facing issues such as interrupted nanofluidic transport and much dissipated heat. Peristome surface of Nepenthes enables stable wetting and rapid directional water transport correlated with orientational sophisticated flow-guiding microstructures, inspiring amelioration of these issues by regulating membrane topographies. A conformal layer-by-layer assembly is adopted to construct superstructured positively charged graphene oxide (PGO)/MXene membranes (SGMMs) that differ from topographies. These membranes enable anion-selective transport enhanced by superstructure configurations via providing more and wider nanofluidic channels than planar PGO/MXene membrane (PGMM). SGMMs with orientational superstructures demonstrate superior wetting performance and directional transport of surface microfluidics compared to PGMM, inducing directional ion transport within nanochannels. Additionally, this superstructure design assists SGMMs to outshine PGMM in photothermal evaporation conspicuously, benefiting from an enlarged surface area and well-regulated surface microfluidic distribution. Eventually, SGMMs enable more remarkable photothermal evaporation-driven ion transport facilitated by directional transport of surface microfluidics and efficient photothermal evaporation. This work emphasizes the significance of membrane topography design for nanofluidic transport toward exploiting the ocean including sunlight, water resources, and ionic energy.