The Thermocapillary Effect on Gas Bubbles Growing on Electrodes of Different Sizes

Recently, the strongly inhomogeneous current density occuring near a microelectrode was identified as driving a thermocapillary electrolyte flow near gas bubbles growing during electrolysis [Massing et.al. Electrochim. Acta 297, 929 (2019) ]. The present paper is investigating this effect in more detail under various operating conditions. Furthermore, by simplified modeling, the question is answered of whether this effect is also of importance at large planar electrodes. The direction of the thermocapillary force on the bubble is found to change from retarding to advancing the bubble release when the size of the electrode is increased. Conclusions are drawn on how the thermocapillary effect at planar electrodes depends on the electrode coverage and the bubble departure size, also considering industrially relevant values of the current density.