Coalescence Induced Self-Propelled Detachment of Surface Bubbles

The dynamics of nucleation, growth, and detachment of gas bubbles has important implications for many catalytic and electrochemical gas evolution reactions in liquids. In the current work, we experimentally and theoretically examine the growth and detachment dynamics of oxygen bubbles from hydrogen peroxide decomposition catalyzed by gold. Bubbles are demonstrated to grow from an oxygen-oversaturated environment. The dynamical evolution of bubbles is influenced by comprehensive effects combining chemical catalysis and physical mass transfer. Self-propelled detachment is visualized and demonstrated to be induced by the coalescence of two bubbles, where the released surface energy upon coalescence is converted to the kinetic energy of the out-of-plane jumping motion of the merged bubble. A scaling dependence of the critical parent bubble size for the jumping behavior is theoretically derived and found to be in agreement with the experimental results. Energy balances reveal that the parent size inequality not only influences the critical size for jumping, but determines how much energy can be provided for the jumping motion. The current results provide both physical insight for the bubble interactions and practical strategies for applications in chemical engineering.