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Issue 33, 2017
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Voltage-activated transport of ions through single-walled carbon nanotubes

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Ionic transport through single-walled carbon nanotubes (SWCNTs) is promising for many applications but remains both experimentally challenging and highly debated. Here we report ionic current measurements through microfluidic devices containing one or several SWCNTs of diameter of 1.2 to 2 nm unexpectedly showing a linear or a voltage-activated IV dependence. Transition from an activated to a linear behavior, and stochastic fluctuations between different current levels were notably observed. For linear devices, the high conductance confirmed with different chloride salts indicates that the nanotube/water interface exhibits both a high surface charge density and flow slippage, in agreement with previous reports. In addition, the sublinear dependence of the conductance on the salt concentration points toward a charge-regulation mechanism. Theoretical modelling and computer simulations show that the voltage-activated behavior can be accounted for by the presence of local energy barriers along or at the ends of the nanotube. Raman spectroscopy reveals strain fluctuations along the tubes induced by the polymer matrix but displays insufficient doping or variations of doping to account for the apparent surface charge density and energy barriers revealed by ion transport measurements. Finally, experimental evidence points toward environment-sensitive chemical moieties at the nanotube mouths as being responsible for the energy barriers causing the activated transport of ions through SWCNTs within this diameter range.

Graphical abstract: Voltage-activated transport of ions through single-walled carbon nanotubes

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Publication details

The article was received on 26 Apr 2017, accepted on 27 Jul 2017 and first published on 28 Jul 2017

Article type: Paper
DOI: 10.1039/C7NR02976D
Nanoscale, 2017,9, 11976-11986

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    Voltage-activated transport of ions through single-walled carbon nanotubes

    K. Yazda, S. Tahir, T. Michel, B. Loubet, M. Manghi, J. Bentin, F. Picaud, J. Palmeri, F. Henn and V. Jourdain, Nanoscale, 2017, 9, 11976
    DOI: 10.1039/C7NR02976D

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