Controlled Fabrication of Iron Oxide/Mesoporous Silica Core-Shell Nanostructures

A simple and reproducible method for the preparation of well-defined iron oxide/mesoporous silica core-shell nanostructure is provided. Iron oxide nanocubes with a narrow size distribution were synthesized through a novel ethanol/acetic acid system using Fe(NO3)center dot 9H(2)O as an iron source and polyvinylpyrrolidone as a capping agent under mild solvothermal conditions (200 degrees C). These monodisperse nanoparticles were used directly as the core for the deposition of a mesoporous silica shell via a sol-gel process, resulting in uniform core-shell Fe2O3@SiO2 composites with tailored silica shell thickness and controllable core morphology. In addition, composition as well as magnetization of the reduced core-shell composites could easily be controlled by a reduction process. Furthermore, the iron oxide core in Fe2O3@SiO2 could be completely etched to produce hollow SiO2 nanospheres. The mechanism of formation of the core-shell structure was also proposed by the aid of IR spectrum analysis.