Improving the water electrolysis performance by manipulating the generated nano/micro-bubbles using surfactants

The impeded mass transfer rate by on-site-generated gas bubbles at both cathode and anode dramatically reduces the energy conversion efficiency of the proton exchange membrane water electrolyzer (PEMWE). Herein, we report a surfactant-assistant method to accelerate the nano/micro-bubble detachment and the mass transfer rate by reducing the surface tension, resulting in an increase in overall efficiency. Four kinds of surfactants are studied in this work. Only potassium perfluorobutyl sulfonate (PPFBS), which has the structural similarity to Nafion, shows a significant promotion of activity and stability for both hygrogen evolution reaction (HER) and oxygen evolution reaction (OER) in the acidic medium at the high current density region. The HER overpotential at 0.1 A.cm(-2) decreased 22%, and the current density at -0.4 V increased 31% by adding PPFBS. The promotion of overall efficiency by PPFBS on a homemade PEMWE was also proven. The reduced surface tension and electrostatic repulsion were the probable origins of the accelerated bubble detachment.

Automated summary

The impeded mass transfer rate by gas bubbles generated on-site significantly reduces the energy conversion efficiency of the proton exchange membrane water electrolyzer. This study demonstrates that a surfactant-assistant method can accelerate the detachment of nano/micro-bubbles and the mass transfer rate, leading to an increase in overall efficiency. One specific surfactant, potassium perfluorobutyl sulfonate, shows significant promotion of activity and stability for hydrogen evolution reaction and oxygen evolution reaction in acidic medium, especially at high current density region.