Preparation of a microelectrode array using desorption of a self-assembled monolayer of hexadecylthiolate on a gold electrode in cyanide solution

The immersion of an Au electrode coated with a self-assembled monolayer of hexadecylthiolate (HDT\Au) in KCN aqueous solution causes desorption of chemisorbed hexadecylthiolate molecules which depends on the immersion time. The desorption is initiated at pinholes of the HDT\Au electrode through which cyanide ions reach the gold substrate, causing desorption of the adsorbed hexadecylthiolate. Electrochemical deposition of copper onto the HDT\Au electrode after immersing the electrode in KCN solution revealed that the size of holes generated by desorption of the adsorbed hexadecylthiolate became large as the immersion time in the KCN solution increased, and the holes produced were distributed fairly homogeneously over the entire surface of the HDT\Au electrode. Detailed simulations of cyclic voltammograms of the HDT\Au electrode obtained in K-4[Fe(CN)(6)] solutions after immersing the electrode in the KCN solution suggested that the HDT\Au electrodes achieved electrochemical activities characteristics of a microelectrode array with this immersion in the cyanide solution. The average radius of the microelectrodes estimated by the best fitting of the experimentally obtained voltammograms to the simulated ones accorded well with that obtained from the observations of the Cu-deposited electrode. (C) 1997 Elsevier Science S.A.