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.