H₂ bubble motion reversals during water electrolysis

Abstract

The dynamics of hydrogen bubbles produced by water electrolysis in an acidic electrolyte is 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 studied systematically. The most prominent one consists of 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.

Mass transport at gas-evolving electrodes

“…2022; Bashkatov et al. 2023). However, thermal Marangoni is likely less of a factor in the present configuration, as our current density does not exceed , which is not sufficient to increase the temperature considerably.…”

Impact of tracer particles on the electrolytic growth of hydrogen bubbles

“…Previous studies already started analyzing the forces acting on a hydrogen bubble attached at an electrode 9,39-42 but did not consider electric force effects that were later found to be essential for completely understanding the different bubble growth regimes. 4,7,28 Recently, Hossain et al 27 accurately took into account all forces by including further geometric and electrochemical details of the experiments. The total force RF on an attached bubble in the vertical direction is given by…”

“…Only recently, it was unveiled that capillary effects and an electric surface charge at the interface may influence the bubble dynamics. [4][5][6][7][8] Most detailed results exist at microelectrodes, where the thermocapillary effect was confirmed to play a major role at large potentials. However, in comparison to measurements and simulations, still considerable differences in the flow pattern and the interfacial velocity profiles in the upper part of the bubble interface persist.…”

Solutal Marangoni force controls lateral motion of electrolytic gas bubbles

“…2,3 An effective management of these interfacial gas bubbles is desirable and requires a better understanding of the multiscale dynamics of bubble nucleation, growth, detachment and transport. [4][5][6][7][8][9][10][11][12] An improved understanding of the motion mechanisms of electrochemically generated gas bubbles is particularly key to design more efficient catalysts and electrochemical devices for various processes.…”