Operando Monitoring of Solid-Liquid Interfaces at Atomic Scale Using Pattern-Enhanced Resonant Soft X-Ray Scattering

Unveiling interfaces at the atomic scale is critical for advancing fundamental understanding of chemical reactions such as water electrolysis. However, probing these interfaces with high spatial and temporal resolution has been challenging. Herein, we apply a novel operando approach, pattern-enhanced resonant soft X-ray scattering (PE-RSoXS), to study solid-liquid interfaces during electrolysis. PE-RSoXS deploys well-ordered line-grating nanopatterns, enhancing the scattering signal and enabling sub-nanometer sensitivity to monitor structural and chemical dynamics at reaction fronts. To demonstrate the capability of this new methodology, we selected electrochemical water oxidation system and utilized the Ni line-grating pattern electrode as a testing platform. Finite-element-method based calculations were conducted to simulate the PE-RSoXS results by varying the interfacial structures and chemical compositions. Furthermore, operando measurements reveal interfacial structural dynamics and chemical transitions of Ni species with millisecond exposure to soft X-rays. These results elucidate PE-RSoXS offers a non-destructive, sensitive approach to probe real-time dynamics at solid-liquid interfaces, facilitating mechanistic insights into chemical transformations.