Highly regenerable carbon-Fe3O4 core–satellite nanospheres as oxygen reduction electrocatalyst and magnetic adsorbent

Abstract We present the synthesis and multifunctional utilization of core-satellite carbon-Fe 3 O 4 nanoparticles to serve as the enabling platform for a range of applications including oxygen reduction reaction (ORR) and magnetic adsorbent. Starting from polydopamine (PDA) nanoparticles and Fe(NO 3 ) 3 , carbon-Fe 3 O 4 core–satellite nanospheres are synthesized through successive steps of impregnation, ammoniation and carbonization. The synergistic combination of Fe 3 O 4 and N-doped carbon endows the nanocomposite with high electrochemical activity in ORR and mainly four electrons transferred in reaction process. Furthermore, carbon-Fe 3 O 4 nanoparticles used as magnetic adsorbent exhibit the efficient removal of Rhodamine B from an aqueous solution. The recovery and reuse of the adsorbent is demonstrated 5 times without any detectible loss in activity.