Controllable synthesis of core–satellite Fe3O4@polypyrrole/Pd nanoarchitectures with aggregation-free Pd nanocrystals confined into polypyrrole satellites as magnetically recoverable and highly efficient heterogeneous catalysts

Abstract

A soft template-assisted simultaneous redox strategy has been developed to fabricate Fe₃O₄@polypyrrole/Pd (Fe₃O₄@PPy/Pd) nanocomposites with a single Fe₃O₄ core and multiple PPy satellites, into each of which multiple tiny Pd nanocrystals are uniformly confined. The dispersion of Pd nanocrystals into PPy satellites and the Pd loading of the nanocatalyst could be finely tuned by tailoring the polarity of the reaction medium and by changing the molar ratio of pyrrole monomer to Pd precursor, respectively. The Pd-based catalyst shows high activity, robust stability and magnetic recyclability for the reduction of nitroaromatic compounds. Superior activity could be attributed to the short transport route toward the active Pd nanocrystals within the small PPy satellite for the outer substitutes. Meanwhile, high stability could be ascribed to the confinement of Pd nanocrystals uniformly into PPy satellites against aggregation and even loss of active sites during catalytic transformations.