Unraveling the Evolution and Regulation Mechanisms of Reversible Exsolution in Perovskite‐Based Nanoparticles

Abstract Nanoparticles (NPs) supported on oxide‐metal catalytic interfaces and formed via the exsolution of metal oxide support enhance various chemical and energy conversion processes. However, the lack of reliable material design principles and precise control methods for NPs still hinders the commercialization of the exsolution technique. Here, a comprehensive mechanistic study is presented on the growth kinetics and redox reversibility of in situ exsolved multimetallic NPs using medium‐entropy perovskite Sr 1.95 Fe 1.2 Cu 0.2 Ru 0.2 Mo 0.4 O 6−δ as a model system. The size, density, and reversibility of exsolved CuRuFe NPs are quantified by regulating the gradient oxygen partial pressure, ambient temperature, and reduction time. The results clarify that environmental factors exhibit a significant volcano‐type effect on the exsolution degree and NP morphology. These factors show distinct dependencies: prolonged reduction duration leads to NP agglomeration, while elevated temperatures promote reversible oxidation. Theoretical calculations further reveal the promoting effect of flexible sites provided by multiple NPs on the C─O bond cleavage process in the CO 2 reduction reaction and the migration mechanism of metal and oxygen species during reversible regeneration. This approach highlights the crucial role of precisely regulating the operating environment in tailoring the dynamic microstructure of the active interface, guiding smart NPs to extend catalyst lifetime.