Bioinspired Ti ₃C ₂T _x MXene‐Based Ionic Diode Membrane for High‐Efficient Osmotic Energy Conversion

Abstract

Bioinspired asymmetric nanofluidic ion channels with ionic diode behavior that can boost the osmotic energy (so‐called blue energy) conversion are highly desirable, especially if they can be easily constructed and modified. Two‐dimensional (2D) metal carbides and nitrides, known as MXenes, combine hydrophilic surfaces and tunable surface charge properties, providing a shortcut to prepare asymmetric nanofluidic ion channels. Here, we report a mechanically robust, flexible, and scale‐up‐friendly asymmetric Ti ₃C ₂T _x MXene‐based ionic diode membrane with a highly rectified current and demonstrate its potential use in reverse electrodialysis osmotic energy conversion. Under the salinity gradient of synthetic seawater and river water, our ionic diode membrane‐based generator‘s power density is 8.6 W m ⁻²and up to 17.8 W m ⁻²at a 500‐fold salinity gradient, outperforming the state‐of‐the‐art membranes. The design of MXene‐based ionic diode‐type membrane provides a facile and general strategy in developing large‐scale 2D nanofluidics and selective ion transport.