BURSTING AND MIXED-MODE OSCILLATIONS DURING THE HYDROGEN-PEROXIDE REDUCTION ON A PLATINUM-ELECTRODE

The occurrence of various sequences of complex bursting and mixed-mode oscillations is described during the hydrogen peroxide reduction on a rotating platinum disk from sulphuric acid solution. It is shown that the current and electrode potential oscillations that occur under fix ed applied potential-conditions are caused by a cathodic passivation p rocess related to a hydride-layer formation, in conjunction with the s olution and external ohmic resistance. Impedance measurements reveal t hat the potential oscillations that can be observed under galvanostati c conditions do not find an explanation in terms of negative impedance characteristics, and hence their origin remains unclear.