In Situ Observation and Electrical Signal Analysis of Different Bubble Detachment Modes on Microelectrode Surface

Abstract

The deactivation of the reaction surface caused by bubble covering is an important factor that causes the decrease in the efficiency of water electrolysis. By combining an electrochemical workstation with a high-speed camera, the evolutionary properties of hydrogen bubble and potential were obtained on a horizontal microelectrode with a diameter of 100 μm. During the electrolysis, individual bubbles evolved periodically on the electrode surface. Under the influence of electrode adsorption, the detachment diameter of the bubble is independent of current density, but with the increase of current density, the bubble detachment frequency increases. With the increase of ethylene glycol (EG) concentration, the bubble detachment frequency increased. When the concentration of EG is greater than 7.5 g l−1, the surface tension of the solution is lower than that of water, at which time the detachment mode of the bubble changes. Separating the resistance caused by the bubbles from the total resistance, it was found that the additional resistance caused by the bubbles rapidly became smaller as the EG concentration increased until the EG concentration reached 7.5 g l−1. The total resistance decreases first and then increases when the EG concentration is greater than 3 g l−1.