STUDY OF THE RELATIONSHIP BETWEEN VOLTAMMETRIC BEHAVIOR AND ELECTROCATALYTIC ACTIVITY IN THE REDUCTION OF CLO4(-) IONS AT PLATINIZED PLATINUM-ELECTRODES

Cyclic voltammetric measurements were carried out with various Pt/Pt electrodes in 3 mol dm-3 HClO4 and 0.5 mol dm-3 H2SO4 electrolytes in order to find a relationship between their voltammetric behaviour in H2SO4 and their activity for the electrocatalytic reduction of ClO4- ions. It was found that the catalytic activity of a platinized electrode, in the reaction studied, depends strongly on the parameters of the platinization method used in its preparation. However, this behaviour cannot be correlated with the height or position of the hydrogen adsorption peaks observed in H2SO4 solution as very different catalytic activity was found in the case of almost similar voltammetric behaviour. It was shown that alternating anodic-cathodic treatments (between 0.05 and 1.4 V) of the various electrodes ''equalize'' their voltammetric behaviour and at the same time minimize their electrocatalytic activity. This phenomenon explains why the electrocatalytic reduction of ClO4- ions escaped the attention of many workers.