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 [email protected] 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 [email protected] Furthermore, the redispersion of palladium in ceria is accompanied by a change in oxidation state and coordination that inhibits the growth of ceria crystallites in the shell, thereby producing sites that better access the reducibility of the ceria shell support. Together, these effects result in a decrease in the temperature required for 90% conversion (T₉₀) of carbon monoxide. Our findings demonstrate that thermally induced restructuring of [email protected] morphologies under controlled conditions provides a strategy for enhancing low-temperature catalytic activity.

中文翻译：

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热诱导重组[受电子邮件保护的] ₂和[受电子邮件保护的] ₂纳米颗粒作为增强低温催化活性的策略

在暴露于高温下之后保持高催化活性仍然是诸如汽车排放控制之类的应用中的关键挑战。尽管催化剂通常会在高温下烧结并在高温下老化后失去活性，但在这里我们说明了[受电子邮件保护]形态的钯的反应截然不同。在氧气中800°C老化后，钯会重新分散到封装壳中。与不可还原的二氧化硅相反，当钯被可还原的二氧化铈包封时，再分散更明显且几乎完成。这种差异可能是由于晶格氧的可用性。通过与表面装饰有Pd的多晶二氧化铈纳米颗粒进行比较，我们表明，在我们简单的老化条件下，为了进行有利的重组，此过程必须从特定的初始配置开始，并受[电子邮件保护]。此外，钯在二氧化铈中的重新分散伴随着氧化态的变化和配位变化，从而抑制了二氧化铈微晶在壳中的生长，从而产生了更易于进入的位置二氧化铈壳载体的还原性。这些效应共同导致90％转化所需的温度降低（一氧化碳的T ₉₀）。我们的发现表明，在受控条件下热诱导的[受电子邮件保护的]形态的重组提供了增强低温催化活性的策略。