One-Step Fabrication of Core–Shell-Structured Pd@NH2–UiO-66(Zr) with “Clean” Pd NPs for Synergistic Catalysis

Abstract

Rational design of MNPs@MOF (MNPs = metal nanoparticles and MOFs = metal–organic frameworks) nanocomposites is crucial for harnessing their synergistic effects as multifunctional catalysts. Herein, a one-pot reaction between a MOF precursor and Pd(NO3)2 in N,N-dimethylformamide (DMF), acting both as the solvent for MOF synthesis and an agent for reduction of Pd2+ to Pd NPs, led to the formation of a core–shell-structured Pd@NH2–UiO-66(Zr) nanocomposite, where surfactant-free Pd NPs of ca. 3 nm were encapsulated within the matrix of NH2–UiO-66(Zr), ascribable to the simultaneously formed MOF protective layer for inhibiting the Pd NPs from growth and aggregation. With unoccupied MOF cavities to facilitate the mass diffusion as well as an efficient charge transfer from the MOFs to “clean” Pd NPs for collaborative catalysis, the as-obtained Pd@NH2–UiO-66(Zr) nanocomposite demonstrated outstanding performance in the reaction between amine compounds and benzyl alcohols to yield secondary amines, especially for large substrate molecules. This study underscores the significance of a rational strategy in constructing MNP/MOF nanocomposites for their application as multifunctional catalysts in light-initiated one-pot tandem/cascade reactions.