Extended Stöber method to synthesize core-shell magnetic composite catalyst Fe3O4@C-Pd for Suzuki coupling reactions

Fe3O4@C core-shell microspheres have been synthesized by the carbonization of Fe3O4@resorcinol-formaldehyde which was obtained with an extended Stöber method. Without additional reducing agents, Pd nanoparticles were successfully immobilized in the shell of microspheres during the carbonization. The size of Pd nanoparticles could be controlled from 3 nm to 10 nm through adjusting the carbonization temperature from 350 °C to 550 °C. Fe3O4@C-Pd core-shell catalyst carbonized at 550 °C shows the highest catalytic performance in Suzuki coupling reaction of iodobenzene and phenylboronic acid. The yield of biphenyl could reach 100% in 30 min and kept over 90% even after ten-times recycling. The magnetic composite catalysts possess high saturation magnetization (54.90 emu·g−1) and can be easily recovered by the aid of an external magnetic field.