Facile fabrication of SiO 2/Al 2O 3 composite microspheres with a simple electrostatic attraction strategy

Abstract

SiO 2/Al 2O 3 composite microspheres with SiO 2 core/Al 2O 3 shell structure and high surface area were prepared by depositing Al 2O 3 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 SiO 2/Al 2O 3 composite microspheres calcined at 600 °C were 653 m 2 g −1 and 0.34 ml g −1, respectively.