Facile fabrication of SiO2/Al2O3 composite microspheres with a simple electrostatic attraction strategy

SiO2/Al2O3 composite microspheres with SiO2 core/Al2O3 shell structure and high surface area were prepared by depositing Al2O3 colloid particles on the surface of monodispersed microporous silica microspheres using a simple electrostatic attraction and heterogeneous nucleation strategy, and then calcined at 600 °C for 4 h. The prepared products were characterized with differential thermal analysis and thermogravimetric analysis (DTA/TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption and X-ray photoelectron spectroscopy (XPS). It was found that uniform alumina coating could be deposited on the surface of silica microspheres by adjusting the pH values of the reaction solution to an optimal pH value of about 6.0. The specific surface area and pore volume of the SiO2/Al2O3 composite microspheres calcined at 600 °C were 653 m2 g−1 and 0.34 ml g−1, respectively.