Cyclic voltammetry on recessed nanodisk-array electrodes prepared from track-etched polycarbonate membranes with 10-nm diameter pores

This paper described cyclic voltammograms (CVs) on a recessed nanodisk-array electrode (RNE) prepared from a track-etched polycarbonate membrane (TEPCM) with 10-nm diameter pores. A RNE was prepared via sputtering of a gold thin film onto a TEPCM whose pores were coated with polyvinylpyrrolidone. CVs of such a RNE changed from peak-shaped to sigmoidal with decreasing scan rate due to the transition of diffusion modes of redox-active molecules, as with previous reports. However, faradic currents in these CVs were larger than theoretical currents calculated from the membrane thickness, pore density, and pore diameter. The larger faradic currents may reflect the presence of a surface layer on TEPCM nanopores to which the redox species preferentially distribute as compared with the nanopore cavity. The limiting current of uncharged 1,1'-ferrocenedimethanol was not affected by solution pH or supporting electrolyte concentration. In contrast, those of anionic ferricyanide and cationic ferrocenylmethyltrimethylammonium decreased and increased, respectively, with increasing pH from 4 to 9. These pH-dependent changes in limiting current were larger at lower supporting electrolyte concentration. The dependence of the CVs on solution pH and supporting electrolyte concentrations was attributed to electrostatic interaction between the redox species and the charged TEPCM nanopores.