Scanning electrochemical microscopy (SECM) was used to deposit and visually characterize localized precipitate microarrays of copper hexacyanoferrate and iron hexacyanoferrate on glassy carbon electrode (GCE), respectively. Dissolution of a sacrificial Cu microelectrode and stripping of Fe pre-deposited on a platinum microelectrode generated relevant metal cations in the gap between the microelectrode and the GCE, which precipitated some [Fe(CN)₆]^4－ anions that were generated simultaneously by reduction of [Fe(CN)₆]^3－ at the GCE. By moving the microelectrode in the “skip-dip deposition” mode, precipitate-dot microarrays of copper hexacyanoferrate (CuHCF) and iron hexacyanoferrate (FeHCF), typically of about 25 μm diameter for each dot, was fabricated, respectively. The diameter and thickness of disk-shaped precipitate dot could be modified by changing the concentration of K₃[Fe(CN)₆] or the deposition time. The deposited metal hexacyanoferrate microstructures showed catalytic activity for the oxidation of dopamine and the reduction of hydrogen peroxide, respectively, which were characterized visually by SECM.

Key words: scanning electrochemical microscopy, microarray, hexacyanoferrate, dopamine, hydrogen peroxide, imaging