3D nm-Thin Biomimetic Membrane for Ultimate Molecular Separation

Multi-functional membranes with high permeance and selectivity that can mimic nature’s designs have tremendous industrial and bio-medical applications. Here, we report a novel concept of a 3D nanometer (nm)-thin membrane that can overcome the shortcomings of conventional membrane structures. Our 3D membrane composes two three-dimensionally interwoven channels that are separated by a continuous nm-thin amorphous TiO2 layer. This 3D architecture dramatically increases the surface area by 6,000 times; coupled with an ultra-short diffusion distance through the 2-4 nm-thin selective layer that allows for ultrafast gas and water transports, ~900 l·m-2·h-1·bar-1. The 3D membrane also exhibits combined size- and charge-based exclusion mechanisms which leads to very high ion rejection (R ~ 100% for potassium ferricyanide). The combination of high ion rejection and ultrafast permeation makes our 3DM superior to state-of-the-art high-flux membranes whose performances are limited by the flux-rejection tradeoff relationship. Furthermore, its ultimate Li+ selectivity over polysulfide or gas can potentially solve major technical challenges in energy storage such as lithium-sulfur or lithium-O2 batteries.