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.