How the porous transport layer/catalyst layer interface affects the performance of PEM electrolyzers

The interfacial structure between the porous transport layer (PTL) and catalyst layer (CL) plays a critical role in determining the performance of PEM water electrolyzers. This study investigates three titanium PTLs—Ti felt, Ti woven mesh, and Ti mesh—focusing on their contact area, contact edge length. Results show that a larger contact area enhances catalyst activation at low current densities, while longer edge length supports uniform reaction distribution and improved transport under high current loads. Excessively wide land regions were found to hinder water accessibility and reduce effective reactive area. A current-dependent transition was observed in the dominant structural factor affecting catalyst utilization, further validated by an equivalent resistance model. These findings highlight that optimizing PTL/CL interfacial geometry is key to enhancing electrolyzer performance beyond material selection alone.