Understanding the Dynamics of Nanoparticle Formation and Evolution in Functional Oxides via In Situ SAXS/WAXS

ABSTRACT The formation and evolution of nanoparticles on the surface of oxide catalysts are essential for determining their catalytic performance. Establishing a direct relationship between structure and function requires real‐time in situ characterization under operational conditions. Multiple techniques can be used to create catalytically active nanoparticles on catalyst surfaces, including traditional deposition or infiltration methods and novel techniques such as exsolution, which allows the in situ growth of stable particles. In this study, we report the first in situ Small‐Angle and Wide‐Angle X‐ray Scattering (SAXS/WAXS) investigation of Ni nanoparticle formation in La _0.85 Sr _0.15 Cr _0.8 Ni _0.2 O _3‐δ (LSCN), where particles emerge via exsolution, and in a reference La _0.85 Sr _0.15 CrO _3‐δ sample with infiltrated Ni (LSC+5N), at synchrotron facilities. The results reveal early nucleation and thermal evolution with high sensitivity and statistical robustness. By tracking nanoparticle formation and evolution during reduction at increasing temperatures, SAXS provides a complementary tool to conventional techniques such as XRD and electron microscopy for real‐time monitoring. This study establishes SAXS/WAXS as a powerful and innovative tool for investigating nanoscale processes in functional ceramic materials, offering new insights into the design of stable and active nanostructured catalysts.