Finite-Element Computer Simulations on Cyclic Voltammograms Measured at Recessed Nanodisk-Array Electrodes

The characteristics of cyclic voltammograms (CVs) at recessed nanodisk-array electrodes (RNEs) were investigated using finite-element computer simulations. Simulations were performed for RNEs based on planar electrodes coated with electrically-insulating films comprising hexagonally-distributed, vertically-oriented cylindrical nanopores (12 nm in radius, 30 nm deep). CVs and concentration profiles of redox species were simulated by varying electrode spacing (2s) and the diffusion coefficient of a redox species within the nanopores (Dpore). For nm-scale s and large Dpore, peak-shaped CVs with currents very similar to those at a film-free electrode were obtained due to the overlapping of diffusion layers extended from multiple electrodes. However, larger s and smaller Dpore gave smaller peak currents, as the nanoscale electrodes limited the number of redox species to be reacted. Further increase in s offered sigmoidal CVs though s was small enough for the overlapping of diffusion layers. These trends were consistent with experimental CVs measured at RNEs.