Enhancement of ionic conductivity in electrically conductive membranes by polarization effect : научное издание

Описание

Тип публикации: статья из журнала

Год издания: 2024

Идентификатор DOI: 10.1016/j.electacta.2024.144994

Аннотация: Electrically conductive nanoporous membranes represent a class of stimuli–responsive materials, which selectivity/permeability characteristics can be adjusted by varying the surface potential. In this work, we perform a comprehensive theoretical and experimental study of ionic conductivity of such membranes. The 2D Space charge andПоказать полностью1D Uniform potential models are used to describe the ion transport through a cylindrical nanopore. The calculations show that the imposed electric field polarizes the conductive surface, which results in the continuous variation of electronic surface charge from positive to negative along the nanopore. A higher concentration of cations (anions) is observed at negatively (positively) charged part of the nanopore. The increase of charge carries concentration due to polarization effect results in the enhancement of ionic conductivity with increasing the voltage difference. The corresponding current–voltage curves are non-linear. The enhancement can reach a few orders of magnitude at low salt concentrations, but becomes much smaller at high concentrations. The presence of chemical charge has a screening effect on the interaction of electric field with the electronic charge on the nanopore surface, and reduces the conductivity enhancement. A novel analytical solution is derived for the dependence of ionic current on the Stern layer capacitance, salt concentration, and the applied potential difference. The theoretical predictions are first confirmed by the ionic conductivity measurements in porous anodic alumina membranes with carbon nanotubes inside the pores. The experimental data are approximated by the 1D Uniform potential model curves using chemical charge as a fitting parameter. Strong enhancement of ionic conductivity (more than 6 times) and the corresponding non-linear dependence of current on the applied voltage is experimentally registered at low KCl concentrations (0.1 – 10 mM) with increasing the voltage difference.

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Издание

Журнал: Electrochimica Acta

Выпуск журнала: Т. 506

Номера страниц: 144994

ISSN журнала: 00134686

Издатель: Elsevier Science Publishing Company, Inc.

Персоны

  • Kharchenko Ivan A. (Siberian Federal University)
  • Vaulin Nikita V. (St. Petersburg Academic University)
  • Simunin Mikhail M. (Federal Research Center KSC SB RAS)
  • Mareev Semen A. (Kuban State University)
  • Nemtsev Ivan V. (Federal Research Center KSC SB RAS)
  • Goltaev Alexandr S. (St. Petersburg Academic University)
  • Lebedev Denis V. (Institute for Analytical Instrumentation RAS)
  • Ryzhkov Ilya I. (Siberian Federal University)

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