A facile template method to fabricate one-dimensional Fe3O4@SiO2@C/Ni microtubes with efficient catalytic and adsorption performance

Abstract

Herein, we report a facile approach for preparing Fe₃O₄@SiO₂@C/Ni microtubes, which could be used as both a catalyst and adsorbent. During the synthetic process, two coating layers (SiO₂ and PDA-Ni²⁺ layers) are polymerized on the surface of MoO₃@FeOOH in turn with an extended Stöber method using MoO₃ microrods as sacrificing templates. Notably, the coating of inorganic SiO₂ and organic PDA-Ni²⁺ layers and the removal of MoO₃ cores are easily achieved simultaneously in ammonia solution with a one-step reaction. Interestingly, the coated silica not only protects the Fe₃O₄ nanoparticles, but also suppresses the reverse electron transfer from PDA to Fe₃O₄ in a calcination process, which leads to the in situ reduction of Ni²⁺ that enhances the dispersibility and density of the Ni nanoparticles. The resulting Fe₃O₄@SiO₂@C/Ni hybrid microtubes can be used as a catalyst towards the reduction of 4-nitrophenol (4-NP) in the presence of NaBH₄. Meanwhile, they also exhibit highly selective adsorption on His-rich proteins (BHb). Moreover, the hybrid microtubes can be conveniently separated with an extra magnetic field due to the presence of Ni and Fe₃O₄, and they show good cyclic stability, which is important for practical applications.