Construction of a thermo-responsive copolymer-stabilized Fe3O4@CD@PdNP hybrid and its application in catalytic reduction

Abstract

A novel and convenient method for fabricating homogeneous nanocatalysts with high catalytic activity and controllable reusability is promising for catalytic reduction. In this study, a high-efficiency magnetic recyclable nanocatalyst (PFe₃O₄@CD@PdNPs) was successfully prepared via depositing highly dispersed palladium nanoparticles (Pd NPs) on a thermo-responsive copolymer support functionalized with superparamagnetic Fe₃O₄ nanoparticles (NPs) with carbon dots (CDs) as both a stabilizing and reducing agent. The thermo-responsive copolymers with catechol end groups could be facilely anchored onto Fe₃O₄ NPs (PFe₃O₄) through a mussel-inspired chemistry strategy. The well-dispersed ultrafine Pd NPs were located on Fe₃O₄ NPs decorated with copolymer brushes using an episulfide ligand-containing copolymer as a costabilizer. Fourier transform infrared spectroscopy, thermogravimetric analysis and other tests proved that the copolymer brushes were successfully grafted on the surface of the Fe₃O₄ NPs. Moreover, transmission electron microscopy and X-ray photoelectron spectroscopy confirmed the presence of CDs in the nanohybrids. In addition, the PFe₃O₄@CD@PdNPs showed interesting thermo-responsive catalytic behaviour because of the presence of thermo-responsive polymer chains on the catalyst surface. Finally, owing to good water dispersibility and the synergistic effect of the Pd NPs with CDs, the PFe₃O₄@CD@PdNP nanocatalyst possessed higher catalytic activity for the catalytic reduction of different dyes and nitrophenols compared with PdNP@PFe₃O₄ without CD modification.