Dynamics of hydrogen bubble movement and oscillation on platinum microelectrodes during water electrolysis

Abstract

Insight into the evolution and movement of bubbles during water electrolysis is crucial to promoting bubble detachment. Here, we investigate the dynamics of hydrogen bubble oscillation on a platinum microelectrode by varying electrolyte species and concentration. The electrolyte series favorable for bubble oscillation is identified as H2SO4 > HCl ≈ HNO3 > HClO4. This series exhibits different bubble evolution modes, from bubble oscillation in sulfuric acid to monotonous growth in perchloric acid. Using the positive feedback relationship between displacement and current, differential equations for bubble motion are established, accurately predicting experimental bubble displacement and oscillation. In the growth controlled by the electrochemical reaction rate, buoyancy drives a linear increase in the oscillation equilibrium position over time. The exponential increase in amplitude arises from the negative damping mechanism induced by the bubble motion and reaction rate. The critical period for bubble oscillation is determined, enabling quantification of the oscillation propensity.