The three-phase transport polarization and structural design status of PEM electrolyzer electrodes

Water electrolysis for hydrogen production is recognized as a vital method for addressing the climate dependence of renewable energy sources. The proton exchange membrane water electrolyzer excels in high current densities and rapid response times, yet its reliance on precious metal catalysts poses challenges for large-scale application due to harsh operational conditions. Low-loading precious metal membrane electrode assemblies can negatively impact both long-term stability and dynamic performance, particularly at elevated current densities due to pronounced three-phase transport polarization losses. To improve energy conversion efficiency, enhanced mass transport is essential, which can be achieved by optimizing channel structures and interfacial properties. This review explores three-phase transport processes, focusing on resistance issues within the proton exchange membrane and catalytic layers while proposing innovative concepts for phase and interlayer interfaces that could advance low precious metal loading electrodes. We summarize structural optimization strategies and field-flow synergy approaches to minimize transport resistances. Overall, we provide insights into the three-phase transport polarization process, address key challenges, and offer conclusions and future directions for improving PEMWE performance.