A facile template method to fabricate one-dimensional Fe 3 O 4 @SiO 2 @C/Ni microtubes with efficient catalytic and adsorption performance

Herein, we report a facile approach for preparing Fe 3 O 4 @SiO 2 @C/Ni microtubes, which could be used as both a catalyst and adsorbent. During the synthetic process, two coating layers (SiO 2 and PDA-Ni 2+ layers) are polymerized on the surface of MoO 3 @FeOOH in turn with an extended Stöber method using MoO 3 microrods as sacrificing templates. Notably, the coating of inorganic SiO 2 and organic PDA-Ni 2+ layers and the removal of MoO 3 cores are easily achieved simultaneously in ammonia solution with a one-step reaction. Interestingly, the coated silica not only protects the Fe 3 O 4 nanoparticles, but also suppresses the reverse electron transfer from PDA to Fe 3 O 4 in a calcination process, which leads to the in situ reduction of Ni 2+ that enhances the dispersibility and density of the Ni nanoparticles. The resulting Fe 3 O 4 @SiO 2 @C/Ni hybrid microtubes can be used as a catalyst towards the reduction of 4-nitrophenol (4-NP) in the presence of NaBH 4 . 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 Fe 3 O 4 , and they show good cyclic stability, which is important for practical applications.