In recent years, noble metals atomically dispersed on solid oxide supports have become a frontier of heterogeneous catalysis. In pursuit of an ultimate atom efficiency, the stability of single-atom catalysts is pivotal. Here we compare two Pd/CeO₂ single-atom catalysts that are active in low-temperature CO oxidation and display drastically different structural dynamics under the reaction conditions. These catalysts were obtained by conventional impregnation on hydrothermally synthesized CeO₂ and one-step flame spray pyrolysis. The oxidized Pd atoms in the impregnated catalyst were prone to reduction and sintering during CO oxidation, whereas they remained intact on the surface of the Pd-doped CeO₂ derived by flame spray pyrolysis. A detailed in situ characterization linked the stability of the Pd single atoms to the reducibility of the Pd–CeO₂ interface and the extent of reverse oxygen spillover. To understand the chemical phenomena that underlie the metal–support interactions is crucial to the rational design of stable single-atom catalysts.

近年来，以原子形式分散在固体氧化物载体上的贵金属已成为多相催化的前沿。为了追求最终的原子效率，单原子催化剂的稳定性至关重要。在这里，我们比较了两种 Pd/CeO ₂单原子催化剂，它们在低温 CO 氧化中具有活性，并在反应条件下显示出截然不同的结构动力学。这些催化剂是通过常规浸渍水热合成的CeO ₂和一步火焰喷射热解获得的。浸渍催化剂中被氧化的Pd原子在CO氧化过程中易于还原和烧结，而它们在Pd掺杂的CeO _{2表面上保持完整}由火焰喷射热解而得。详细的原位表征将 Pd 单原子的稳定性与 Pd-CeO ₂界面的还原性和反向氧溢出的程度联系起来。了解构成金属-载体相互作用的化学现象对于合理设计稳定的单原子催化剂至关重要。