Development of an electrode-membrane-electrode system for selective Faradaic response towards charged redox species

We investigate the Faradaic currents of ferrocene species at an electrode-membrane-electrode system. The membrane electrodes system is fabricated by physical sputtering of conductive metal on both sides of a nanoporous alumina membrane. The metal coatings function as working electrodes by connection to a bipotentiostat and reference/counter electrodes in the sample solution. Collection and shielding efficiency studies are carried out at this membrane electrodes system to measure mobility values of charged ferrocene species within nanochannels of alumina membrane. Results indicated high selective electrode response of up to 16 times for positively charged (dimethylaminomethyl)ferrocene (FcN), and neutral ferrocenemethanol (FcMeOH), compared to the negatively charged ferrocenecarboxylic acid (FcCOOH) when the receiver electrode was maintained at negative potentials of 0.5–1.0 V relative to the feed electrode. This is a report on the use of an electrode-membrane-electrode system to achieve selective response towards differently charged redox species, under the condition of high electrolyte concentration (0.1 M, pH 7.0 phosphate buffer).