Facet Engineering of a Metal–Organic Framework Support Modulates the Microenvironment of Palladium Nanoparticles for Selective Hydrogenation

Abstract The exposed facets of supported catalysts play a crucial role in catalysis; however, they are usually ignored and related studies remain rare. Herein, we have fabricated a series of sandwich‐structured metal–organic framework composites, denoted ZIF‐8 X @Pd@ZIF‐8 (x represents the morphology of ZIF‐8 core, i.e., ZIF‐8 C exposing (100) facet, ZIF‐8 RD exposing (110) facet, and ZIF‐8 TRD exposing mixed (100) and (110) facets), featuring Pd nanoparticles deposited on the specific crystal facets of ZIF‐8 core, for hydrogenation of p ‐chloronitrobenzene. The Pd electronic state is tailored by the ZIF‐8 core, where more electron‐deficient Pd is found in ZIF‐8 C @Pd@ZIF‐8 than that in ZIF‐8 RD @Pd@ZIF‐8, leading to discriminative adsorption of the −NO 2 and −Cl groups of p ‐chloronitrobenzene. Consequently, ZIF‐8 C @Pd@ZIF‐8 exhibits excellent activity (97.6 %) and selectivity (98.1 %) to p ‐chloroaniline. This work highlights crystal facet engineering of supports to modulate the microenvironment and electronic state of supported metal nanoparticles, offering a promising avenue to enhanced catalysis.