Experimental and mathematical modeling of mass transfer dynamics of hydrogen bubbles on textured electrodes during electrochemical water splitting

The interplay between bubble release dynamics and surface wettability profoundly influences the performance of water dissociation systems; a topic not well understood. To systematically study the effect of electrode geometry and wettability, we have employed additive manufacturing to fabricate textured 316L-stainless steel electrodes composed of well-arranged pillars with different geometries and hydrophilicity. Through combined experimental and simulation approaches using bubbly flow models, we demonstrate that geometrically-induced wettability significantly affects hydrogen bubble dynamics, transitioning from gas-filled to liquid-filled states, and modulates bubble growth and detachment mechanisms. It is shown that the kinetics of bubble release and the surface coverage on hemispherical-topped pillars can finely be tuned to reduce the transport overpotential by 68.8 % and to increase the Faradaic efficiency (FE) by 191.5 % at -300 mA cm-2 relative to untextured electrodes. These findings delineate a pragmatic approach toward the design of textured electrodes for efficient gas-evolving reactions.