Anode catalyst layer with hierarchical pore size distribution for highly efficient proton exchange membrane water electrolysis

Anode catalytic layer (ACL) plays a vital role in developing a highly efficient proton exchange membrane water electrolyzer, yet its reaction activity and mass transfer at high operating current density remain a challenge. To address this issue, an innovative configuration design of ACL with three sub-layers is constructed in the form of hierarchical pore size distribution. The hierarchical structure of ACL with increasing pore size away from the membrane exhibits superior electrochemical performance (2.043 V @ 3 A cm−2), which is 163 mV lower than that of ACL without pore-forming treatment. The mercury intrusion porosimetry results demonstrate that the porosity increases from 38.8% to 52.3% after the pore-forming treatment. Electrochemical characterization analyses further indicate that the hierarchical structure of ACL enhances active site amount, kinetics, and mass transfer. Therefore, the pore-forming treatment for the anode catalytic layer is a simple and efficient approach to achieving superior electrolysis performance.