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Abstract:
The removal of microbubbles from substrates is crucial for the efficiency of many catalytic and
electrochemical gas evolution reactions in liquids. The current work investigates the coalescence and
detachment of bubbles generated from catalytic decomposition of hydrogen peroxide. Self-propelled
detachment, induced by the coalescence of two bubbles, is observed at sizes much smaller than those
determined by buoyancy. Upon coalescence, the released surface energy is partly dissipated by the bubble
oscillations, working against viscous drag. The remaining energy is converted to the kinetic energy of the
out-of-plane jumping motion of the merged bubble. The critical ratio of the parent bubble sizes for the
jumping to occur is theoretically derived from an energy balance argument and found to be in agreement
with the experimental results. The present results provide both physical insight for the bubble interactions
and practical strategies for applications in chemical engineering and renewable energy technologies like
electrolysis.
