No abstract

Retaining high catalytic activity after exposure to elevated temperatures remains a crucial challenge for applications such as automotive emissions control. While catalysts generally sinter and lose activity after aging at high temperature, here we illustrate that palladium in a core@shell morphology responds very differently. After 800 °C aging in oxygen, palladium redisperses into the encapsulating shell. The redispersion is more pronounced, and nearly complete, when palladium is encapsulated by reducible ceria, as opposed to nonreducible silica. This difference is likely due to the availability of lattice oxygen. Through comparisons with polycrystalline ceria nanoparticles, surface decorated with Pd, we show that for favorable restructuring to occur under our simple aging conditions, the process must start from a particular initial configuration, the

The catalytic activity is enhanced by Ce but inhibited by La dopant. The catalysts have been characterized in light of structural properties, reducibility, mobility of adsorbed oxygen and lattice oxygen, and surface reaction intermediates.