Effect of electrode diameter on H2 bubble dynamics at platinum microelectrodes

Understanding and regulating bubble generation and motion during water electrolysis is crucial for promoting bubble detachment and enhancing electrolytic performance. Electrode diameter is a key intrinsic parameter governing bubble behavior, yet its quantitative impact on bubble evolution regimes and oscillatory dynamics remains unclear. This study investigated the influence of platinum microelectrode dimensions on H 2 bubble dynamics by varying electrode diameter and cathode potential, combined with high-speed imaging and in-situ electrochemical measurements. Findings revealed that as electrode diameter decreased, bubble detachment cycles significantly lengthened, while the average detachment radius and current simultaneously decreased. A critical threshold diameter of approximately 400 μm is identified: beyond this value, the bubble evolution regime transitions from periodic single-bubble detachment to multi-bubble detachment. The oscillation frequency of bubbles decreases with increasing electrode diameter, while larger electrodes require higher cathode potentials to induce oscillatory behavior. The larger the electrode diameter, the higher the cathode potential required to trigger bubble oscillation; if the diameter increases further, the bubbles will be released in a multi-bubble form. • Revealed the effect of electrode diameter on bubble evolution parameters. • Determined that bubble evolution regime is regulated by electrode size and potential. • Electric field force increases with increasing electrode geometric scale. • Elucidated the influence of electrode diameter on bubble oscillation behavior.