Formation of Fe₃O₄@C/Ni microtubes for efficient catalysis and protein adsorption

In the recent years, the fabrication of functional nanostructures with multicomponent has received considerable attention due to their exceptional properties. Herein, we report a facile approach for the preparation of Fe₃O₄@C/Ni microtubes, which could be used as both a catalyst and the adsorbents. During the synthetic process, a layer of nickel ion-doped polydopamine (PDA-Ni²⁺) was polymerized in situ on the surface of the MoO₃@FeOOH by an extended stöber method using MoO₃ microrods as the sacrificing templates. Notably, the PDA-Ni²⁺ coating and the removal of the MoO₃ cores were carried out simultaneously during the coating of the PDA-Ni²⁺ in an ammonia solution. Then the prepared FeOOH@PDA-Ni²⁺ microtubes were converted to Fe₃O₄@C/Ni hybrid microtubes through a pyrolysis with a thermochemical reduction process. The resulting Fe₃O₄@C/Ni hybrid microtubes were used as a novel catalyst towards the reduction of 4-nitrophenol (4-NP) in the presence of NaBH₄. Moreover, they also exhibited highly selective adsorption on His-rich proteins (BHb). Moreover, the Fe₃O₄@C/Ni hybrid microtubes can be conveniently separated by an external magnetic field due to the presence of Ni and Fe₃O₄. Furthermore, they show good cyclic stability, which is important for the practical applications.