Low‐Friction Graphene Oxide‐Based Ion Selective Membrane for High‐Efficiency Osmotic Energy Harvesting

Abstract

Graphene‐based laminate membranes with selective ion‐transport capability show great potential in renewable osmotic energy harvesting. One of the great challenges is to reduce the overall energy barriers while remain the high ion selectivity in the transmembrane ion transport process. Here, a strategy is proposed to break the trade‐off between ion selectivity and permeability in laminar nanochannels using amphiphilic molecules as modifier, which enhances the surface charge density of nanochannel by loading more ion polymer with polar head and lows the frictional force of ion transport with hydrophobic tail. The conversion efficiency can reach to 32% in osmotic energy harvesting (0.5 m/0.01 m concentration gradient) after adopting this modifier. During the process of mixing real river water and seawater, the maximum power density can reach to 13.38 W m−2. The amphiphilic molecules also bind adjacent nanosheets, endowing the membrane's strong mechanical strength and high stability in aqueous solution. This work can open up a new way to regulate the transmembrane ion transport in 2D laminate membranes.

Decoupled Ionic and Electronic Pathways for Enhanced Osmotic Energy Harvesting

“…However, biomembrane systems, such as lipid bilayers, frequently exhibit poor mechanical properties, environmental stability, and working performance, thus failing to use efficient biomembranes to fabricate osmotic energy devices. Various biomimetic nanofluid material platforms, including membrane-based, − hydrogel-based, , and fiber-based − platforms, are currently studied, which involve homogeneous or blended zero–two-dimensional nanomaterials and three-dimensional polymer networks to construct nanostructures with customizable physical structure and chemical properties to enhance osmotic energy collection. Notably, for blended membranes coupled with polymers and functional nanomaterials (GO-SNF, , GO-ANF, GO/CNF, , MXene/CNF, and NB/ANF), the effect of nanomaterials on the charge density of the system and the geometric structure of the nanochannel has been widely investigated, and then the composition of fillers has substantially improved the ion-transport resistance and reduced the intrinsically high internal resistance of biomass materials .…”