Advanced in-situ analysis of anion-exchange membrane water electrolysis to correlate structure-reactivity-stability with performance

• Recent advances in anion-exchange membrane water electrolysis (AEMWE) analysis • In situ analyses of the structure, reactivity, and stability of AEMWE systems • Single-cell-level in situ imaging of gas evolution and operando analyses • Crucial role of in situ diagnostics in AEMWE commercialization Anion-exchange membrane water electrolysis (AEMWE) is gaining recognition as a promising approach for sustainable hydrogen production that combines the advantages of both alkaline and proton-exchange membrane technologies. Nonetheless, the performance and durability of AEMWE are significantly influenced by real-time structural and chemical transformations of the catalysts, ionomers, and membranes during operation. Traditional ex-situ techniques fail to capture these dynamic changes, thereby hindering the design of robust materials. In contrast, in-situ and operando methods enable the direct observation of catalyst reconstruction, degradation paths, and interfacial phenomena during electrolysis. This review highlights recent advances in various in-situ techniques, including transmission electron microscopy, Raman spectroscopy, X-ray absorption spectroscopy, and scanning electrochemical microscopy, which aid in elucidating the relationships between the structure, reactivity, and stability of AEMWE systems. It also discusses the in-situ imaging of gas evolution and operando analyses at the unit-cell level, providing vital insights into mass transport and failure mechanisms. Systems that are both durable and exhibit high performance can be developed through the integration of these methods. Finally, this review underscores the importance of in-situ diagnostics, which are crucial for the commercialization of AEMWE.