Hydrogen bubble growth at micro-electrode under magnetic field

• Micro-MHD restraining effect on the hydrogen bubble growth was analyzed.
• The rotating flow brings lower pressure regions closing to the bubble bottom.
• The magnetic field reduces the bubble growth rate.

The effect of magnetic field, with perpendicular to working electrode surface configuration, on the hydrogen bubble evolution at 0.2 mm diameter micro-electrode was investigated in sulfuric acid solution. This paper analyzed the periodical bubble growth and detachment within the current density range of 15.9–57.3 A/cm2. As the current density increases, the bubble release frequency becomes larger without magnetic field. While the bubble becomes more difficult release, and the larger current density brings smaller release frequency under magnetic field. The further computational fluid dynamics (CFD) analysis found that a pair of lower pressure regions was formed as the rotating flow of fluid around the bubble driven by the Lorentz force. The pressure difference plays the role of stabilizing the bubble at the micro-electrode surface under magnetic field.