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Tetraalkylammonium Cations Conduction through a Single Nanofluidic Diode: Experimental and Theoretical Studies

Ali, Mubarak and Ramirez, Patricio and Nasir, Saima and Cervera, Javier and Mafe, Salvador and Ensinger, Wolfgang :
Tetraalkylammonium Cations Conduction through a Single Nanofluidic Diode: Experimental and Theoretical Studies.
[Online-Edition: https://doi.org/10.1016/j.electacta.2017.08.078]
In: Electrochimica Acta, 250 pp. 302-308. ISSN 00134686
[Article] , (2017)

Official URL: https://doi.org/10.1016/j.electacta.2017.08.078

Abstract

We describe experimentally and theoretically the concentration-dependent conduction of tetraalkylammonium (TAA+) cations through a nanofluidic diode fabricated in a polymer membrane via asymmetric track-etching techniques. This single-pore membrane exhibits current rectification characteristics because of the ionized carboxylate groups on the pore surface. We use aqueous solutions of potassium (K+), ammonium (A+), tetramethylammonium (TMA+), tetraethylammonium (TEA+), and tetrabutylammonium (TBA+) ions with concentrations ranging from 50 to 500 mM under acidic (pH 3.5) and physiological (pH 6.5) conditions. Compared with the K+ and A+ ions, the TMA+, TEA+, and TBA+ ions show relatively low rectified ion currents because the cation hydrophobicity increases with the alkyl chain. At low concentrations and acidic conditions, an inversion in the current rectification characteristics is observed, which is attributed to the adsorption of the organic cations on the pore surfaces. The experimental results can be analyzed in terms of the Poisson-Nernst-Planck equations and the geometrical and electrical single pore characteristics for the different ions, pH values, and salt concentrations employed. This theoretical approach is qualitative and could be extended further to include a self-consistent theoretical treatment of the ionic adsorption and surface charge equilibria.

Item Type: Article
Erschienen: 2017
Creators: Ali, Mubarak and Ramirez, Patricio and Nasir, Saima and Cervera, Javier and Mafe, Salvador and Ensinger, Wolfgang
Title: Tetraalkylammonium Cations Conduction through a Single Nanofluidic Diode: Experimental and Theoretical Studies
Language: English
Abstract:

We describe experimentally and theoretically the concentration-dependent conduction of tetraalkylammonium (TAA+) cations through a nanofluidic diode fabricated in a polymer membrane via asymmetric track-etching techniques. This single-pore membrane exhibits current rectification characteristics because of the ionized carboxylate groups on the pore surface. We use aqueous solutions of potassium (K+), ammonium (A+), tetramethylammonium (TMA+), tetraethylammonium (TEA+), and tetrabutylammonium (TBA+) ions with concentrations ranging from 50 to 500 mM under acidic (pH 3.5) and physiological (pH 6.5) conditions. Compared with the K+ and A+ ions, the TMA+, TEA+, and TBA+ ions show relatively low rectified ion currents because the cation hydrophobicity increases with the alkyl chain. At low concentrations and acidic conditions, an inversion in the current rectification characteristics is observed, which is attributed to the adsorption of the organic cations on the pore surfaces. The experimental results can be analyzed in terms of the Poisson-Nernst-Planck equations and the geometrical and electrical single pore characteristics for the different ions, pH values, and salt concentrations employed. This theoretical approach is qualitative and could be extended further to include a self-consistent theoretical treatment of the ionic adsorption and surface charge equilibria.

Journal or Publication Title: Electrochimica Acta
Volume: 250
Publisher: Elsevier Science Publishing
Uncontrolled Keywords: tetraalkyammonium cations, biomimetic nanopore, current rectification, nanofluidic Diode, Nernst-Planck equation
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Material Analytics
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 28 Dec 2017 11:59
DOI: 10.1016/j.electacta.2017.08.078
Official URL: https://doi.org/10.1016/j.electacta.2017.08.078
Funders: M. A., S. N., and W.E. acknowledge the funding from the Hessen State Ministry of Higher Education, Research and the Arts, Germany, under the LOEWE project iNAPO., P. R., J. C., and S. M. acknowledge financial support by the Spanish Ministry of Economic Affairs and Competitiveness (MAT2015-65011-P) and FEDER.
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