Aggregation- and Leaching-Resistant, Reusable, and Multifunctional Pd@CeO2 as a Robust Nanocatalyst Achieved by a Hollow Core-Shell Strategy

To develop various strategies to prevent the aggregation, sintering, or leaching of noble metal nanoparticles (NPs) represents a crucial issue for efficient synthesis and utilization of supported noble metal NPs with highly active and stable catalytic performance. Here, we report a facile synthesis approach to obtain a Pd@hCeO(2) hollow core shell nanocomposite that is composed of tiny Pd nanoparticles cores encapsulated within CeO2 hollow shells. The core shell strategy efficiently prevents the aggregation of Pd NPs in the high temperature calcination process and the leaching of Pd NPs for the catalytic reaction in a liquid phase. This anti aggregation and anti leaching behavior is not able to be achieved for traditional supported Pd/CeO2 catalyst. Such a Pd@hCeO(2) composite can serve as an efficient multifunctional nanocatalyst in both heterogeneous thermocatalytic and photocatalytic selective reduction of aromatic nitro compounds in water under ambient conditions. Each component, namely Pd metal core or semiconductor CeO2 shell, makes a necessary but totally dissimilar reactive contribution to achieving the same end product during these two different catalytic processes. Importantly, Pd@hCeO(2) exhibits an excellent reusable and much higher catalytic performance than supported Pd/CeO2. This work provides a generic concept example on inhibiting aggregation of noble metal NPs during high temperature calcination and leaching of noble metal nanoparticles into solution via a hollow core shell strategy, and, more significantly, on sufficiently harnessing the specific metal core or semiconductor shell function integrated in a core shell nanoarchitecture toward a multifunctional catalytic use in both thermocatalytic and photocatalytic selective green transformation in water.