A novel magnetic mesoporous core–shell nanocomposite Fe3O4@nSiO2@mSiO2@Ni–Co–B was prepared by the combination of a modified Stöber sol–gel process, a surfactant-templating method and self-assembly. It has a multi-shell structure with ferroferric oxide as core, dense nonporous silica and mesoporous silica as middle layers in sequence and an Ni–Co–B amorphous alloy as outer layer, as confirmed by transmission electron microscopy and nitrogen adsorption–desorption. This nanocomposite showed high activity and good selectivity in the selective hydrogenation of cinnamic acid to hydrocinnamic acid. Notably, it can be easily separated by a magnet after reaction due to its high magnetism and recycled effectively five times.
