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

Abstract

This study investigates the structural stability of small Pd@Pt core@shell octahedral nanoparticles (NPs) and their shell thickness dependent catalytic performance for p-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 p-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 p-chloronitrobenzene hydrogenation.

Encapsulation of Bimetallic Metal Nanoparticles into Robust Zirconium‐Based Metal–Organic Frameworks: Evaluation of the Catalytic Potential for Size‐Selective Hydrogenation

“…Zhang et al. found similar trends for octahedral core–shell PdPt NPs during the hydrogenation of 4‐chloronitrobenzene . It should be noted that the material Pd 1 Pt 1 @UiO‐66 fully reduces NB quantitatively to aniline within 2 h at room temperature with a metal/substrate ratio of 1:800, which is superior to the previously synthesized Pd@UiO‐67 system.…”

“…This reveals the importance of the shell thickness and composition in general. It is known that thinner shells can give higher shell metal dispersion as well as stronger core–shell interactions, thus resulting in a higher activity . Therefore, it is assumed that the thick Pt shell eliminates or strongly reduces the positive electronic effect of the core metal (Pd) and simultaneously prevents migration of Pd atoms to the surface as it was observed in case of Pd 1 Pt 1 with equimolar ratio of both metals.…”

Core–shell nanoparticles: synthesis and applications in catalysis and electrocatalysis

“…[299][300][301] Nanomaterial-catalyzed hydrogenations of alkynes, alkenes, aromatic nitro compounds and ketones have received much interest in the last decade because of their use in the synthesis of important raw materials along with the remarkable effectiveness of nanomaterials in catalyzing such reactions. [308][309][310][311] 4.1.1. Among such processes, catalytic transfer hydrogenation (CTH) reaction is becoming increasing popular because of its wide usage and versatility.…”

Effects of Pt shell thickness on self-assembly monolayer Pd@Pt core-shell nanocrystals based hydrogen sensing

“…Among the various bimetallic nanostructures, core-shell nanocrystals have attracted considerable interest due to their outstanding interplanar surface interaction, synergetic interplay of the bi-functional configuration, large surface-tovolume ratio, and quantum size, while their use can potentially reduce the consumption of precious metals [13e15]. Moreover, the good distribution of the thin atomic layer of the shell metal promotes preferential core-shell interaction, thus providing evidence for superior specific activity [16].…”