RESUMO
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.
RESUMO
Using the LabVIEW™ graphical programming language designed by National Instruments®, a digital simulation model has been developed in order to describe electrochemical processes occurring at rotating ring-disk electrodes. The model allows for taking into consideration independent potential control of the two working electrodes, homogeneous electrode reactions, as well as spatial inhomogeneities of the working electrode surfaces. The main programming concepts, as well as the operation of the simulation software is presented. Several test simulations have been carried out in order to evaluate the accuracy of the calculations.