Evaluating the Effect of Electrode-normal Magnetic Field on the Bubbles Grown on Horizontal Microelectrodes

Water electrolysis is the most feasible way to product super-pure hydrogen. Relatively low efficiency is the greatest obstacle to the popularization of water electrolysis. It was found that imposing magnetic field can increase hydrogen production efficiency, but the detailed mechanism of the enhancement is still lacking an insight understanding regarding to the micro vicinity of the bubbles. To further this research, an alkaline water electrolysis experiment using microelectrodes is performed under the influence of a magnetic field. The bubbles generated on the microelectrodes can be divided into two groups according to their size, and a force analysis of these bubbles was processed. The quantified forces acting on bubbles shows that magnetic field has little impact on the relatively large bubble, but the rotating flow around the large bubble has a considerable impact on the micron-sized bubbles generated at the foot of the big bubble according to the experimental observation. The rotational flow can take micron bubbles away before they converge with large bubbles. This phenomenon may responsible for slower bubble detachment and longer bubble growth cycle in alkaline electrolyte when a magnetic field imposed. The results indicate that probably we should not only focus on the big bubble but the micro bubbles below it, whether magnetic field apply to plate electrodes or other types of electrodes.