Mussel-Inspired Catechol–Formaldehyde Resin-Coated Fe3O4 Core–Shell Magnetic Nanospheres: An Effective Catalyst Support for Highly Active Palladium Nanoparticles

Magnetic Fe3O4@catechol–formaldehyde resin (CFR) core–shell nanospheres were fabricated via a controllable hydrothermal method. The shell thickness of Fe3O4@CFR nanospheres can be effectively regulated in the range of 10–170 nm via adjusting reaction parameters. In particular, catechol groups on the surface of nanospheres also play a significant role in mussel-inspired chemistry to further combine with graphene oxide (GO) to wrap the Fe3O4@CFR spheres. The obtained Fe3O4@CFR and Fe3O4@[email protected] nanospheres can be used as the effective catalyst supports of small Pd nanoparticles (PdNPs, <10 nm) formed via an in situ synthesis route. The as-fabricated nanohybrid catalysts of Fe3O4@[email protected] and Fe3O4@[email protected]@PdNPs with excellent dispersibility and stability are reusable after magnetic separation from catalytic systems. In particular, a super active performance was demonstrated for the catalytic reduction of methylene blue dye with highest turnover frequency (5260 min–1) yet reported in the literature using a very low dosage of the Fe3O4@[email protected]@PdNP catalyst. In addition, the Fe3O4@[email protected]@PdNP catalyst also exhibits a highly catalytic efficiency for the Suzuki coupling reaction using pure water as a green solvent at room temperature