Design of honeycomb pattern on catalyst layer for bubble management in PEM water electrolysis

Oxygen bubble accumulation on the anode catalyst layer in proton exchange membrane water electrolysis (PEMWE) can block active sites, leading to increased mass transport losses and performance degradation. To address this issue, the honeycomb pattern catalyst layer was developed to facilitate the rapid detachment of oxygen bubbles and enhance reactant accessibility. First, we experimentally evaluated the performance of the honeycomb pattern catalyst layer compared to the reference catalyst layer. Experimental evaluations demonstrated that the honeycomb pattern catalyst layer reduced the cell voltage by 0.15 V at 1.18 A/cm² compared to the reference catalyst layer. As a result of analyzing each overpotential, the honeycomb pattern catalyst layer exhibited lower ohmic and mass transport overpotentials, indicating improved reactant accessibility. Secondly, we performed numerical simulations to analyze the exposure time of the activated region during oxygen bubble growth. Simulations of bubble behavior revealed that the honeycomb structure accelerated the exposure of active areas by controlling bubble growth and detachment. Further investigation into the pitch effect revealed that a 1.12 mm pitch separated oxygen bubbles up to 23.1 % faster. However, when the PTL porosity decreases, the active area is secured more quickly at a pitch of 1.68 mm. This is because lower porosity suppresses the growth of oxygen bubbles, causing the oxygen bubble neck to shrink more slowly. Through this study, it was observed that PTL porosity influences oxygen bubble growth, whereas pitch affects oxygen bubble detachment. This study highlights the importance of catalyst layer design in mitigating bubble-induced losses and improving PEMWE performance.