Size Effects on Bubble Dynamics during Photoelectrochemical Water Splitting

The rapid bubble removal from electrodes diminishes the reaction resistance within photoelectrochemical water splitting, and the coalescence between bubbles accelerates their detachment. To delve into the size effects on bubble coalescence dynamics, the Marangoni effect is utilized as a noninvasively controlling means of bubble sliding and coalescence. The study reveals that the encounter of capillary waves induces bubble detachment. A quantitative correlation has been established to elucidate the relationship between the oscillation time of coalescence and the capillary wave propagation. Then, the bubbles undergo damping oscillations due to fluid resistance after detaching, characterized by the same dimensionless oscillation periods. Additionally, the detachment velocity of the bubbles follows a power law relationship of 1/2 with the ratio of dimensionless surface energy to the equivalent radius. Considering the viscous dissipation and adhesive effect of the electrode on the bubbles, the critical radius of large bubbles enabling jumping is deduced from the perspective of energy conservation. Our research provides a strategy for the management of bubble dynamic behavior and the practical application of electrolysis technology.