  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.
