The well-defined rattle-type magnetic silica nanocomposite had been synthesized through a facile sol–gel process accompanied by a hard-template method. Structural characterizations indicated that the fabricated nanocomposite, denoted as γ-Fe2O3@SiO2–@mSiO2, was composed of nonporous silica-coating magnetic iron oxide encapsulated in mesoporous silica hollow sphere. The textural parameters of the nanocomposite are adjustable by controlling the preparation conditions. The unique structure of the prepared nanocomposite showed relatively high methylene blue adsorption capability and can be used for removal of dye from aqueous solution. In addition, some active metallic nanoparticles (such as Pt, Pd) can be introduced into the cavity of γ-Fe2O3@SiO2–@mSiO2 to construct confined integrated catalytic system. The designed Pt-based integrated nanocatalyst exhibited not only high activity and selectivity, but also an excellent reusability for the selective hydrogenation of nitrobenzol to aniline. The existence of magnetic core in the nanocomposite provides a facile separation from liquid solution.

A well-defined core–shell nanocomposite with magnetic iron oxide nanoparticles coated by a hierarchically structured silica shell has been synthesized through a sol–gel process and pseudomorphic transformation. The prepared materials were characterized by means of transmission electron microscopy, small and wide angle X-ray diffraction, Mössbauer spectroscopy and N2 physical adsorption–desorption. It has been shown that the core–shell nanocomposite possesses a magnetic core in the form of Fe3O4 or γ-Fe2O3 and a unique hierarchically structured silica shell consisting of an inner nonporous shell and outer shell with hierarchical pores. As a result, this nanocomposite exhibits high stability (acid resistance) and a large surface area (447 m2 g−1), which will be especially suitable for use as catalyst supports. To demonstrate this point, a functional catalyst consisting of small Pt nanoparticles well-dispersed on the porous surface of the magnetic core–shell nanocomposite was fabricated. In the hydrogenation of nitrobenzene and 2-nitrochlorobenzene to the corresponding aniline compounds, the hierarchically porous catalyst showed superior performances to its counterpart with a monomodal porous structure. In addition, the used catalyst could be separated conveniently from the reaction system with an external magnetic field. Subsequent recycling tests further confirmed the outstanding reusability and regeneration ability of the composite catalyst.

Magnetic resorcinol/formaldehyde resin (RF) and silica/RF nanocomposites with well-defined core–shell architecture and tunable structural parameters had been prepared via the extended Stöber method. The carbon counterparts with similar structure and morphology can be obtained by thermal-treating the polymer precursors under N2 atmosphere. The prepared materials were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Mössbauer spectroscopy, N2 physical adsorption/desorption, and thermogravimetric analysis. The catalytic applications of the synthesized magnetic nanocomposites were also explored. It has been shown that the magnetite core was oxidized to γ-Fe2O3 during polymer coating process and further reduced to original Fe3O4 phase during carbonization. In addition, the iron oxide core can react with the shell when carbonization temperature reaches 700 °C. The structural stability of magnetic silica/RF is superior to magnetic RF because of the existence of an inner silica shell. Through a simple deposition–precipitate method, active platinum nanoparticles can be loaded in high dispersity onto the surface of the nanocomposites. The constructed magnetic catalysts are very active in hydrogenation of nitroarenes to corresponding amines and can be separated facilely with an external magnetic field.

A well-defined core–shell nanocomposite with magnetic iron oxide nanoparticles coated by a hierarchically structured silica shell has been synthesized through a sol–gel process and pseudomorphic transformation. The prepared materials were characterized by means of transmission electron microscopy, small and wide angle X-ray diffraction, Mössbauer spectroscopy and N2 physical adsorption–desorption. It has been shown that the core–shell nanocomposite possesses a magnetic core in the form of Fe3O4 or γ-Fe2O3 and a unique hierarchically structured silica shell consisting of an inner nonporous shell and outer shell with hierarchical pores. As a result, this nanocomposite exhibits high stability (acid resistance) and a large surface area (447 m2 g−1), which will be especially suitable for use as catalyst supports. To demonstrate this point, a functional catalyst consisting of small Pt nanoparticles well-dispersed on the porous surface of the magnetic core–shell nanocomposite was fabricated. In the hydrogenation of nitrobenzene and 2-nitrochlorobenzene to the corresponding aniline compounds, the hierarchically porous catalyst showed superior performances to its counterpart with a monomodal porous structure. In addition, the used catalyst could be separated conveniently from the reaction system with an external magnetic field. Subsequent recycling tests further confirmed the outstanding reusability and regeneration ability of the composite catalyst.