Highly Stable and Magnetically Recyclable Mesoporous Silica Spheres Embedded with FeCo/Graphitic Shell Nanocrystals for Supported Catalysts

We have synthesized highly stable and magnetically recyclable mesoporous silica spheres embedded with FeCo-graphitic carbon shell nanocrystals (FeCo/GC@MSS) by a simple one-step chemical vapor deposition (CVD) method. Solid core-mesoporous shell silica spheres with an average diameter of ∼400 nm are used as supports not only for the synthesis of the FeCo/GC nanocrystals but also for catalysts after the synthesis of the FeCo/GC@MSS. The FeCo/GC nanocrystals in the mesoporous silica spheres exhibit superparamagnetism with ultrahigh saturation magnetization up to 215 e.m.u./metal g at room temperature. The FeCo/GC@MSS is chemically stable against acid etching and oxidation, which enable the FeCo/GC@MSS to be used as a support for an acid catalyst, phosphomolybdic acid (PMA). We have shown that PMA-loaded FeCo/GC@MSS works as an excellent recyclable reagent system that catalyzes propargylation of 1,3-diphenyl-2-propyn-1-ol with phenol.