Topologically Programmed Graphene Oxide Membranes with Bioinspired Superstructures toward Boosting Osmotic Energy Harvesting

The emergence of lamellar nanofluidic membranes offers feasible routes for developing highly efficient, mechanically robust, and large-scale devices for osmotic energy harvesting. However, inferior ion permeability associated with their relatively long channels limits ionic flux and restricts their output performance. Herein, a superstructured graphene oxide membrane is developed to allow programmable topological variation in local geometry and contain laminar spaces inside. Such deliberate design offers excess specific area as well as nanofluidic channels to modulate transmembrane ionic transportation while concomitantly retaining similar nanoconfined environment in contrast to planar ones, leading to considerable enhancement of ionic permeability without compromising selectivity. This can be highly favorable in terms of osmotic energy harvesting, where the superstructured membranes offer a power output much higher than those of conventional planar ones. Besides, the superstructure design also endows the resulting membranes with benign biofouling resistance, which can be crucial to their long-term usage in converting osmotic energy. This study highlights the importance of membrane topographies and presents a general design concept that could be extended to other nanoporous membranes to develop high-performance nanofluidic devices.