Facile Hydrogen-Bond-Assisted Polymerization and Immobilization Method to Synthesize Hierarchical Fe_3O_4@Poly(4-vinylpyridine-co-divinylbenzene)@Au Nanostructures and Their Catalytic Applications

摘要

Hierarchical Fe_3O_4@poly(4-vinylpyridine-co-divinylbenzene)@Au (Fe_3O_4@P(4-VP-DVB)@Au) nanostructures were fabricated successfully by means of a facile two-step synthesis process. In this study, well-defined core-shell Fe_3O_4@P(4-VP-DVB) microspheres were first prepared with a simple polymerization method, in which 4-VP was easily polymerized on the surface of Fe_3O_4 nanoparticles by means of strong hydrogen-bond interactions between -COOH groups on poly(acrylic acid)-modified Fe_3O_4 nanoparticles and a 4-VP monomer. HAuCl_4 was adsorbed on the chains of a P(4-VP) shell and then reduced to Au nanoparticles by NaBH_4, which were embedded into the P(4-VP) shell of the composite microspheres to finally form the Fe_3O_4@P(4-VP-DVB)@Au nanostructures. The obtained Fe_3O_4@P-(4-VP-DVB)@Au catalysts with different Au loadings were applied in the reduction of 4-nitrophenol (4-NP) and exhibited excellent catalytic activity (up to 3025 h~(-1) of turnover frequency), facile magnetic separation (up to 31.9 emug~(-1) of specific saturation magnetization), and good durability (over 98% of conversion of 4-NP after ten runs of recyclable catalysis and almost negligible leaching of Au).