The motion of electrolytic gas bubbles near electrodes

Several reports in the literature mention oscillatory bubble motions close to, or in contact with electrodes. Such behaviour is obviously related to a time-variable force, but it was not apparent what the origin of this variable force was. Recent advances in understanding of the surfactant behaviour of gases, and in particular the gases liberated during electrolysis, have cast a new light on the underlying mechanism of these oscillations. Other unexpected, but not necessarily oscillatory bubble behaviour is discussed, and the role of electrolytic gas acting as a surfactant illuminates these non-oscillatory motions as well. Finally, the paradox of bubbles remaining attached to electrodes with zero contact angle is resolved. (C) 2002 Elsevier Science Ltd. All rights reserved.