Electrically controlled water permeation through graphene oxide membranes

• Published in: Nature (London) Vol. 559; no. 7713; pp. 236 - 240
• Main Authors: Zhou, K.-G., Vasu, K. S., Cherian, C. T., Neek-Amal, M., Zhang, J. C., Ghorbanfekr-Kalashami, H., Huang, K., Marshall, O. P., Kravets, V. G., Abraham, J., Su, Y., Grigorenko, A. N., Pratt, A., Geim, A. K., Peeters, F. M., Novoselov, K. S., Nair, R. R.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.07.2018; Nature Publishing Group
• Subjects: 140/133; 140/146; 639/301/357/1018; 639/638/298/918/1053; 639/766/25; 639/925/918; Capillaries; Carbon; Containers; Electric fields; Experiments; Filaments; Freezing; Graphene; Graphite; Humanities and Social Sciences; Humidity; Ionic strength; Letter; Mass spectrometry; Membranes; Microscopy; multidisciplinary; Penetration; Physicochemical properties; Purification; Science; Science (multidisciplinary); Scientific imaging; Stability; Technology; Tissue engineering; Transport; Water; Water chemistry; Water purification; Water transport
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-018-0292-y

Controlled transport of water molecules through membranes and capillaries is important in areas as diverse as water purification and healthcare technologies 1 – 7 . 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 3 , 8 . Electrical control over water transport is an attractive alternative; however, theory and simulations 9 – 14 have often yielded conflicting results, from freezing of water molecules to melting of ice 14 – 16 under an applied electric field. Here we report electrically controlled water permeation through micrometre-thick graphene oxide membranes 17 – 21 . Such membranes have previously been shown to exhibit ultrafast permeation of water 17 , 22 and molecular sieving properties 18 , 21 , 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. The rapid water transport through graphene oxide membranes can be switched off by introducing localized electric fields within the membranes that ionize surrounding water molecules and thus block transport.