Kinetically Stabilized Pd@Pt Core–Shell Octahedral Nanoparticles with Thin Pt Layers for Enhanced Catalytic Hydrogenation Performance

This study investigates the structural stability of small Pd@Pt core@shell octahedral nanoparticles (NPs) and their shell thickness dependent catalytic performance for <i>p</i>-chloronitrobenzene hydrogenation with H₂. The 6–8 nm Pd@Pt octahedral NPs are prepared by a sequential reduction method, and the characterization results confirm that Pd@Pt octahedral NPs with one to four atomic Pt layers can be controllably synthesized. The Pd@Pt octahedral NPs with one atomic Pt layer demonstrate excellent structural stability with the maintenance of core–shell structures as well as high catalytic stability during cycle to cycle catalytic <i>p</i>-chloronitrobenzene hydrogenation reactions. The alumina-supported Pd@Pt octahedral NPs illustrate a superior catalytic performance relative to individual Pt and Pd and their physical mixtures. Theoretical calculations by density functional theory suggest that the unexpected structural stability for Pd@Pt octahedral NPs with thin Pt shells and their corresponding catalytic stability during hydrogenation reactions can be ascribed to the strong binding between Pt surfaces and reactants/products in catalytic reactions. The enhanced catalytic performance of Pd@Pt octahedral NPs possibly originates from the core–shell interaction, which adjusts the electronic state of surface Pt atoms to be suitable for selective <i>p</i>-chloronitrobenzene hydrogenation