THE HYDRODYNAMICALLY SQUARE-WAVE MODULATED ROTATING-RING-DISK ELECTRODE - THEORETICAL BASIS AND ITS EXPERIMENTAL-VERIFICATION

The hydrodynamically square wave modulated rotating ring-disk electrode can be used for the investigation of electrochemical processes even under conditions for which the ring current is normally masked by a large background current. After stepping of the rotation speed, relatively large changes of the ring current (spikes) are observed. An analytical expression was found to describe the maximum of the change of the collection efficiency when the ring current is independent of the angular velocity of the electrode for stationary (steady-state) conditions. Investigations are made to show the influence of electrode acceleration on this maximum. Experiments with a corroding iron disk and analysis of the dissolution products at the ring in sulfuric acid showed good agreement with the theoretical calculations.