Fabrication of nanoscale gold disk electrodes using ultrashort pulse etching

A novel method for preparing a nanometer-sized gold disk electrode is described. The electrode was fabricated by electrochemical etching of a gold wire, insulating the etched wire with a varnish with the exception of the apex, and cutting down the apex by applying ultrashort (40 ns) etching pulses in an HCl solution. Cyclic voltammograms of a 0.10 M ferrocyanide solution recorded at the electrode showed that a series of etching pulses gradually reduced the diffusion-limited current at the electrode by etching its apex. Characterization by cyclic voltammetry and scanning electron microscopy revealed the transformation of a cone-shaped apex into a disk-shaped electrode with a radius of typically between 50 and 250 nm.