Monodisperse α-Fe2O3@SiO2@Au core/shell nanocomposite spheres:: synthesis, characterization and properties

A new hybrid spherical structure alpha-Fe2O3@SiO2@Au with a size of about 141 nm was designed, with a hematite cubic core surrounded by a thick silica shell and further decorated with gold nanoparticles. The monodisperse alpha-Fe2O3@ SiO2 spheres were first prepared by a sol - gel process based on the modified Stober method. Subsequently, the surface of the alpha-Fe2O3@SiO2 particles was functionalized by -NH2 functional groups. The electrostatic attraction of -NH2 groups will attach the negatively charged Au nanoparticles to the amino-functionalized alpha-Fe2O3@SiO2 nanospheres in order to prepare alpha-Fe2O3@SiO2 monodisperse hybrid spheres. The M( H) hysteresis loop for alpha-Fe2O3@SiO2 and alpha-Fe2O3@SiO2 Au spheres indicates that the nanocomposite spheres exhibit superparamagnetic characteristics at room temperature. The optical properties and the application of these hybrid nanocomposites as catalysts for the conversion of CO to CO2 have also been studied.