ELECTROCHEMICAL AND MIRAGE DETECTION STUDIES OF SPUTTERED IRIDIUM OXIDE-FILMS

The present paper describes electrochemical measurements and ion flux detection performed on sputtered iridum oxide films (SIROFs) in contac t with aqueous solutions of variable pH or neutral alkali electrolytes . These experiments show that the shape of the voltammograms is highly dependent on the electrolyte, varying from a capacitive response to a double-peak shape. The SIROF electrode charge, however, does not depe nd on whether the film shows a capacitive or a peak-shaped voltammogra m. The Probe Beam Deflection technique (mirage effect) shows that capa citive voltammograms correspond to an H+ or HO- exchange while peak-sh aped voltammograms exhibit a complex double ion flux. It is concluded that the charge of the iridium oxide films is mainly faradaic, whateve r the shape of the voltammogram, capacitive or not.