H$_2$ bubble motion reversals during water electrolysis

TL;DR

This study investigates hydrogen bubble dynamics during water electrolysis, revealing motion reversals caused by buoyancy and thermocapillary effects through controlled experiments and optical techniques.

Contribution

It introduces a systematic analysis of bubble interaction scenarios and explains motion reversals using combined electrochemical and optical methods.

Findings

Identified three bubble interaction scenarios.

Documented motion reversal phenomena during bubble detachment.

Attributed reversals to buoyancy and thermocapillary forces.

Abstract

The dynamics of hydrogen bubbles produced by water electrolysis in an acidic electrolyte are studied using electrochemical and optical methods. A defined cyclic modulation of the electric potential is applied at a microelectrode to produce pairs of interacting H$_2$ bubbles in a controlled manner. Three scenarios of interactions are identified and systematically studied. The most prominent one consists in a sudden reversal in the motion of the first detached bubble, its return to the electrode and finally its coalescence with the second bubble. Attested by Toepler's schlieren technique, an explanation of contactless motion reversal is provided by the competition between buoyancy and thermocapillary effects.