Force balance of hydrogen bubbles growing and oscillating on a microelectrode.

Hydrogen evolution in acidic aqueous electrolytes was recently found to be characterized by a carpet of microbubbles covering the microelectrode and feeding the growth of the main bubbles by coalescence. Besides this, oscillatory behavior of the main bubbles was observed prior to departure. Extending earlier studies, this work delivers the forces acting on the main bubble more accurately by taking into account further geometric and electrochemical details measured during experiments. Combining simulation work and measurements makes it possible to confirm the role of an attractive electrical (Coulomb) force caused by the adsorption of hydrogen ions at the bubble interface and to obtain a better understanding of the bubble dynamics observed.