Electrically controlled water permeation through graphene oxide membranes

Abstract

Controlled transport of water molecules through membranes and capillaries is important in areas as diverse as water purification and healthcare technologies. Previous attempts to control water permeation through membranes (mainly polymeric ones) have concentrated on modulating the structure of the membrane and the physicochemical properties of its surface by varying the pH, temperature or ionic strength. Electrical control over water transport is an attractive alternative; however, theory and simulations have often yielded conflicting results, from freezing of water molecules to melting of ice under an applied electric field. Here we report electrically controlled water permeation through micrometre-thick graphene oxide membranes. Such membranes have previously been shown to exhibit ultrafast permeation of water and molecular sieving properties, with the potential for industrial-scale production. To achieve electrical control over water permeation, we create conductive filaments in the graphene oxide membranes via controllable electrical breakdown. The electric field that concentrates around these current-carrying filaments ionizes water molecules inside graphene capillaries within the graphene oxide membranes, which impedes water transport. We thus demonstrate precise control of water permeation, from ultrafast permeation to complete blocking. Our work opens up an avenue for developing smart membrane technologies for artificial biological systems, tissue engineering and filtration.

2D Laminar Membranes for Selective Water and Ion Transport

“…Electrical conductivity is another property intrinsically possessed by 2D nanosheets and well preserved after stacking, which enables the direct use of laminar membranes as electrodes. Externally applied potential (or current) easily gets across the whole membrane and induces additional electric fields inside 2D channels to govern water and ions diffusion . The electrical regulation over water permeation can be achieved by mediating the ionization degree of water molecules in nanochannels.…”

Continuously Producing Watersteam and Concentrated Brine from Seawater by Hanging Photothermal Fabrics under Sunlight

“…Since seawater is one of the most abundant resources covering ≈75% of the earth's surface, seawater desalination has been considered as the most promising technology to offer a constant supply of fresh water. Currently, several desalination methods have been well developed, such as membrane filtration, reverse osmosis, thermal distillation, and solar‐enabled evaporation . Among these methods, solar‐enabled seawater evaporation is an essential global process of water circulation.…”

Solvation‐Involved Nanoionics: New Opportunities from 2D Nanomaterial Laminar Membranes

“…This strategy allows the cost‐effective production of 2D‐NLMs with tunable nanochannels at large scale . Given the ease of synthesis, high‐level structural tunability and versatility, 2D‐NLMs have been extensively explored for confined molecular and ion transport by many research groups including Gao, Geim, Gogotsi, Guo, Huang, Jin, Li, Mi, Nair, Ren, Zhu, and more. The following section will lay out some of the typical attributes of 2D‐NLMs obtained by cascading to correlate with the advances in solvation‐involved nanoionics research.…”