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Polarity-Dependent Electrochemically Controlled Transport of Water through

Summary: Polarity-Dependent Electrochemically
Controlled Transport of Water through
Carbon Nanotube Membranes
Zuankai Wang,,| Lijie Ci,,| Li Chen, Saroj Nayak, Pulickel M. Ajayan,*, and
Nikhil Koratkar*,
Department of Mechanical, Aerospace and Nuclear Engineering, Department of
Materials Science and Engineering, and Department of Physics, Applied Physics and
Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180
Received December 6, 2006; Revised Manuscript Received January 24, 2007
We demonstrate here that water can be efficiently wet and pumped through superhydrophobic aligned multiwalled nanotube membranes by
application of a small positive dc bias. At a critical bias (1.7 V), with the membrane acting as anode, there is an abrupt transition from a
superhydrophobic to hydrophilic state. Interestingly, this phenomenon is strongly polarity dependent; for a negative bias applied to the membrane,
2 orders of magnitude higher bias is required for the transition. The polarity and voltage-dependent wetting that we report could be used to
controllably wick fluids through nanotube membranes and could find various applications.
The wettability and capillary transport of water through car-
bon nanotube membranes have generated much interest1-7
due to the fundamental biological interest of water flow
through nanochannels and for several applications8-12


Source: Ajayan, Pulickel M. - Department of Mechanical Engineering and Materials Science, Rice University


Collections: Materials Science