A Cathode Is the Key Contributor to the Initial Degradation of Anion Exchange Membrane Water Electrolyzers

Understanding early stage degradation in anion exchange membrane water electrolyzers (AEMWEs) is critical, as the majority of the long-term performance loss arises during the initial phase of operation. In this study, we employed a membrane-extended three-electrode system to investigate the origins of initial degradation under dual electrolyte feeding and dry cathode configurations. Contrary to the commonly held assumption that the anode is the bottleneck, electrochemical analysis revealed that the cathode was the dominant contributor to early performance loss, primarily due to pronounced increases in both kinetic and residual overpotentials. Notably, the degradation rate under dual electrolyte feeding conditions was nearly twice that observed under dry cathode operation, primarily due to accelerated Pt agglomeration, which led to increased overpotentials and loss of active sites, emphasizing the impact of cathodic environments. These findings underscore the central role of cathode stability and highlight that tailoring the cathodic environment is an effective strategy to mitigate initial degradation in AEMWEs.