Supercritical CO2-assisted preparation of catalytically-active Pd/Ni nanoparticle-embedded carbon from a metal-organic framework

Abstract

A metal nanoparticle (NP)-carbon composite derived from metal-organic frameworks (MOFs) has garnered significant attention for its high catalytic activity. This study develops a simple method for preparing Pd/Ni NP-embedded carbon from MOFs. Palladium(Ⅱ) acetate (Pd(OAc)2) is used as the precursor for Pd NPs and is loaded into the pores of Ni-MOF-74 using supercritical carbon dioxide (scCO₂) assisted immobilization. Pd/Ni NPs are prepared by reduction and pyrosis of Pd(OAc)2-loaded Ni-MOF-74. Scanning transmission electron microscopy (STEM) clearly reveals that the Pd/Ni NPs are successfully immobilized in the carbon (Pd/Ni@C) and dispersed with sizes around 10 nm. Pd/Ni@C demonstrates high catalytic activity and high durability in Suzuki–Miyaura coupling reactions, despite having lower Pd content (4.7 wt%) than commercially available Pd@C (10 wt%). The active palladium species Pd(0) on Pd/Ni@C accelerated the Suzuki-Miyaura coupling reactions, because the Ni in Pd/Ni NPs played the sacrificial role to resist Pd-oxidation.