Rapid detachment of hydrogen bubbles for electrolytic water splitting driven by combined effects of Marangoni force and the electrostatic repulsion

Abstract

Electrolysis efficiency is significantly hindered by the bubbles on the electrode surface. Therefore, understanding the bubble evolution process is vital to achieve faster detachment at smaller radii. This study experimentally investigates the impact of surface tension and cathodic potential on hydrogen bubble evolution. The findings indicate that adding a small amount (1 × 10−7 M) of anionic surfactant to the acidic solution (1 M H2SO4) results in a 10% reduction in the bubble detachment radius and a substantial decrease in the bubble growth time by approximately 89%. Additionally, further increasing the surfactant concentration has minimal effect on the growth time but continues to lead to the detachment radius decrease which is assumed to be due to the decreased Marangoni force. This study also identifies three distinct bubble growth modes at different surfactant concentrations, linked to varying levels of surfactant adsorption. Furthermore, a force balance model has been developed to describe the bubble growth process. The study concludes that the solutal Marangoni force decreases while electrostatic repulsion increases with rising surfactant concentration. A reduced solutal Marangoni force and increased electrostatic repulsion – are likely the key factors contributing to the accelerated bubble detachment.