Electrochemical transport properties of a cone-shaped nanopore: revisited

There are reports in the literature that a single cone-shaped nanopore generated in a polymer foil separating two equally concentrated dilute aqueous potassium chloride solutions can reach high and low stationary electrical conductivity states respectively depending on the sign of the applied electrical potential. On the basis of published data it has been argued (D. Woermann, Phys. Chem. Chem. Phys., 2003, 5, 1853) that this phenomenon can be understood in terms of a well established model describing the electrochemical transport properties of polyelectrolyte membranes ("model of the membrane with narrow pores"). In the present contribution experimental evidence is presented which gives strong support to these arguments using a model system. Based on the "model of the membrane with narrow pores" a composite membrane is constructed mimicking the structure and electrochemical function of an ensemble of conical nanopores. It is found that the characteristic electrochemical transport property of the composite membrane is that of a cone-shaped nanopore.