Metal–Support Interaction Tuned by Oxygen Chemical Potential Governs Coarsening of Metal Nanoparticles Exsolved from Perovskite Oxides

Metal exsolution from perovskite oxides is a promising strategy for fabricating durable catalysts of uniformly dispersed nanoparticles that are anchored to an oxide matrix. However, recent studies have shown that exsolved nanoparticles may still undergo coarsening over extended operating periods, posing challenges for long-term stability. In this work, we show that the strength of the metal-support interaction (MSI) between exsolved metal nanoparticles and the oxide matrix, tuned by the oxygen chemical potential, governs the dominant coarsening pathways of exsolved nanoparticles. We found a volcano-like relationship between MSI strength and the coarsening or growth rate of nanoparticles subjected to long-time annealing. We further reveal that weak MSI induced by a high surface oxygen vacancy concentration can accelerate particle migration and coalescence, while strong MSI led by a higher oxygen chemical potential favors Ostwald ripening, while both can cause instability of exsolved nanoparticles. These insights can inform the design of durable nanocatalysts by offering a mechanistic understanding of particle growth in metal exsolution.