γ-Al(2)O(3) supported Pd@CeO(2) core@shell nanospheres: salting-out assisted growth and self-assembly, and their catalytic performance in CO oxidation

In this paper, we have successfully demonstrated the clean synthesis of high-quality Pd@CeO(2) core@shell nanospheres with tunable Pd core sizes in water, and furthermore loaded the as-obtained Pd@CeO(2) products on commercial γ-Al(2)O(3)via electrostatic interaction. KBr here plays two key roles in inducing the growth and self-assembly of Pd@CeO(2) core@shell nanospheres. First, Br(–) ions can retard the reduction of Pd(2+) ions via the formation of the more stable complex of [PdBr(4)](2–) so as to tune the size of Pd cores. Second, it greatly decreases the colloidal stability, and hence the surface polarity-weakened Pd and CeO(2) NPs have to spontaneously self-assemble into more stable and ordered structures. Among different-sized Pd samples, the as-obtained 8 nm-Pd@CeO(2)/Al(2)O(3) one exhibits the best performance in catalytic CO oxidation, which can catalyze 100% CO conversion into CO(2) at 95 °C, which is much lower than the previously reported CeO(2)-encapsulated Pd samples.