LASER DEPASSIVATION OF A CHANNEL FLOW DOUBLE-ELECTRODE - A NEW TECHNIQUE IN REPASSIVATION STUDIES

A powerful tool for distinguishing between the different electrochemical steps involved during a depassivation-repassivation sequence was developed by combining the pulsed laser depassivation technique with an hydrodynamic electrochemical method: the channel flow double-electrode (CFDE). This experiment consisted of transporting the chemical species (Fe2+) released by a depassivated iron electrode to a collecting electrode where these species were oxidized. A qualitative idea of the relative contribution of the anodic dissolution to the repassivation behavior was obtained. For a passive iron in acidic solution it was found that about 15% of the total charge is related to anodic dissolution.