Renewable Intermittency Redistributes Catalyst Recovery and Membrane Degradation in Anion Exchange Membrane Water Electrolysis

ABSTRACT Renewable intermittency is widely regarded as a durability stressor in water electrolysis, yet its impact on competing degradation and recovery processes within the cell remains unclear. Here, we show that realistic intermittent operation redistributes catalyst recovery and membrane degradation in anion exchange membrane water electrolysis (AEMWE). A Ni–Fe‐based AEMWE single‐cell was operated under high‐resolution, solar‐mimicking load profiles that reproduce day–night intermittency without external buffering. Electrochemical diagnostics reveal reversible changes in activation, Ohmic, and mass‐transport losses, indicating partial performance recovery during zero‐current intervals. In situ X‐ray absorption spectroscopy attributes this behavior to reversible oxidation‐state and coordination changes of Ni and Fe, associated with the reversible formation and relaxation of amorphous (oxy)hydroxide surface layers. In contrast, hydrogen crossover measurements reveal increased crossover under low‐current operation, while post‐mortem membrane analyses provide independent evidence of membrane deterioration, identifying a critical system‐level limitation. These results show that intermittency does not uniformly mitigate degradation but redistributes it across cell components, enabling catalyst self‐restoration while exacerbating membrane vulnerability. This work establishes intermittency as a double‐edged operational parameter and provides a framework for designing materials and operating strategies for durable, battery‐free AEM water electrolysis.