Coating Fe3O4 spheres with polypyrrole-Pd composites and their application as recyclable catalysts

•Fe3O4@SiO2-SO3H spheres were obtained by a facile coating process.•Fe3O4@SiO2-SO3H spheres provided an effective platform to load Pd2+ ions for oxidative polymerization of pyrrole.•The as-prepared Fe3O4@SiO2-SO3H@PPy-Pd nanocomposites exhibited excellent catalytic activity.

In this work, we reported one-step deposition of the 3-(mercaptopropyl)trimethoxysilane on magnetic Fe3O4 spheres to form well-defined core-shell Fe3O4@SiO2-SH spheres. The thiol (SH) groups could be converted easily to sulfonic acid (SO3H) groups with H2O2 and the as-obtained Fe3O4@SiO2-SO3H spheres were used as a platform for loading Pd2+ ions. The Pd2+ ions anchored on the Fe3O4@SiO2-SO3H spheres acted both as an oxidant for pyrrole monomer and as a source of palladium atoms, yielded polypyrrole(PPy)-Pd composites around the Fe3O4@SiO2-SO3H spheres. This strategy is very facile for fabricating magnetic conducting polymer-noble metal composites and the as-prepared Fe3O4@SiO2-SO3H@PPy-Pd composite spheres could act as efficient catalysts in reduction of 4-nitrophenol and Suzuki coupling reaction due to their high activity, ease of separation, and excellent reusability.

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