Smart construction of palladium@polypyrrole nanocomposite coating on a magnetic support as a highly efficient and recyclable catalyst

Abstract

This work presents a facile and straightforward method for fabricating multifunctional nanocomposite particles, which consist of polystyrene (PS) particles decorated with Fe₃O₄ nanoparticles (NPs) as a magnetic core and palladium (Pd) NP-embedded polypyrrole (PPy) as a nanocomposite shell. In detail, the PS/Fe₃O₄ nanocomposite particles were first prepared through an electrostatic self-assembly between the positively charged Fe₃O₄ NPs and negatively charged PS particles; then, the nanocomposite shell containing PPy and Pd NPs (Pd@PPy) on the as-prepared PS/Fe₃O₄ nanocomposite particles was readily formed in one-step by means of the “Swelling–Diffusion–Interfacial Polymerization Method” (SDIPM). The formation of the Pd@PPy nanocomposite shell was directly achieved using PdCl₂ as the oxidant for pyrrole. As a result, the synthetic approach in this work for such a multifunctional nanostructure has several remarkable advantages, including: (1) greatly simplified synthetic protocols, independent of any surface pretreatments of the prepared PS particles, Fe₃O₄ NPs, or PS/Fe₃O₄ nanocomposite particles; (2) the judicious use of pyrrole and PdCl₂, leading to a simple one-step preparation of the functional Pd@PPy nanocomposite shell on the magnetic support; (3) easy modulation of the thickness of the Pd@PPy nanocomposite shell and the mass loading of Pd NPs inside the PPy matrix by tuning the feed amount of pyrrole and PdCl₂. More importantly, the as-synthesized PS/Fe₃O₄/Pd@PPy nanocomposite particles showed high catalytic activity in the degradation of methylene blue, a typical dye pollutant, with NaBH₄ and can be reused for several cycles with high stability through convenient magnetic separation.