Electrochemical Reduction of Perchlorate Ions on Ruthenium

The reduction of perchlorate ions at ruthenium electrodes was investigated by voltammetry, chronoamperometry, impedance spectroscopy, and by measuring changes of interfacial stress changes using the cantilever bending method as functions of electrode potential, and concentrations of perchloric acid and HCl. The cyclic voltammograms recorded at a rotating (Ru) disc electrode were highly asymmetric with respect to the electrode potential axis, and a negative current could be observed even during the positive sweep. Chloride ions decrease the interfacial stress and exert an inhibiting effect on the reduction process indicating the role of competitive adsorption. The desorption rate of Cl depends strongly on the hydrodynamic conditions, probably through desorption/diffusion coupling. These results serve as a warning that in perchlorate-containing solutions in contact with Ru the adsorption of chloride ions may also influence the rate of other electrochemical processes.