Enhancing hydrogen bubble release from a microelectrode through precise tuning of Marangoni forces with nonionic surfactant

Abstract

Understanding and controlling hydrogen bubble growth and detachment during water electrolysis is crucial for improving its efficiency. This study investigates bubble dynamics for hydrogen evolution on a platinum microelectrode in an acidic electrolyte with different gas/electrolyte surface tensions by adding varying surfactant concentrations. Three hydrogen bubble evolution patterns were observed: periodic detachment of individual bubbles at low surfactant concentrations of 0 and 1 × 10−7 M, respectively; one or two small bubbles are formed at the foot of the bubble during the evolution of single main bubble at intermediate surfactant concentrations of 1 × 10−6 and 1 × 10−5 M; and periodic detachment of large bubbles with aperiodic release of tiny bubbles at higher surfactant concentrations of 1 × 10−4 M. The concentration Marangoni force on individual H2 bubbles decreases significantly with surfactant concentration. This results in shorter evolution cycles from 138.12 to 6.98 s at −0.6 V vs the saturated calomel electrode, reduced detachment radii from 765.95 to 359.54 μm at −0.6 VSCE, and accelerated hydrogen bubble growth. This finding offers a new way to control bubble dynamics during electrochemical bubble formation.