A hierarchical flow field design enabling enhanced mass transfer and performance in PEM water electrolysis

Proton exchange membrane water electrolysis (PEMWE) has emerged as a promising technology for hydrogen production. As a critical component of PEMWE systems, the flow field significantly impacts cell performance and two-phase flow dynamics. In this study, a novel double-layer flow field (DFF) structural design is introduced based on conventional interdigitated anode flow field configurations, with subsequent investigation of its effects on electrochemical performance and two-phase mass transfer characteristics. Electrochemical characterization reveals that the DFF configuration outperforms both serpentine and interdigitated flow fields through reduced ohmic and mass transfer overpotentials. Interface contact resistance measurements demonstrate reduced ohmic losses via improved interfacial electrical contact between the flow field and porous transport layer (PTL). In-situ visualization indicates that the unique architecture of DFF promotes bubble detachment and enhances water supply to the PTL, thereby optimizing two-phase flow mass transfer. Numerical simulations further confirm that the DFF structure accelerates bubble expulsion in flow channels, ensuring uninterrupted water supply to the PTL, thereby enhancing two-phase flow dynamics. These findings provide valuable insights for flow field optimization and mass transfer enhancement in PEMWE systems.