One-pot hydrothermal synthesis of Pd/Fe3O4 nanocomposite in HEPES buffer solution and catalytic activity for Suzuki reaction

Abstract

The Pd/Fe3O4 nanocomposite integrates versatile Pd nanocatalysts with magnetic separation, and has great potential in fine chemical and pharmaceutical synthesis. Its preparation usually involves multi-steps. Herein it was prepared via a facile one-pot hydrothermal synthesis in 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer solution with the assistant of polyvinylpyrrolidone (PVP). HEPES plays multi-functions, particularly as a ligand to enhance the oxidation of Fe2+ to Fe3+ and as a buffer to control the pH value at slightly basic conditions (ca. 7.4) for the formation of crystalline Fe3O4 phase via Fe2+/Fe3+ co-precipitation. PVP works as a dispersant to prevent the particle from aggregation. The obtained Pd/Fe3O4 nanocomposite comprised uniform Pd nanoparticles (ca. 5nm) deposited on Fe3O4 nanocrystals (ca. 15nm). It exhibited excellent catalytic activity and stability for various Suzuki coupling reactions, and could be efficiently recovered with a magnet and recycled for at least 10 cycles without losing catalytic activity.