The Effects of Calcination Conditions on the Properties of TiO2-Al2O3 Composite Materials

TiO2-Al2O3 composite material was prepared by a sol-gel method using a sol mixture derived from tetrabutyl titanate and aluminium isopropoxide. Crystalline structure, surface morphology, composition, BET surface area, and pore size distribution of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Xray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and N2-adsoption and desorption. The composite materials are composed of anatase TiO2 and amorphous Al2O3. There is no apparent difference in surface morphology among the samples calcinated at different temperature. Titanium is in its full oxidation state and there is no reduced titanium state existing in TiO2-Al2O3 composite. The existence of Al2O3 causes binding energies shift to higher energy end for Ti2p3/2, Ti2p1/2, and O1s levels. Specific surface area of the composite samples decreases and TiO2 crystallite size increases with increasing calcination temperature. The TiO2-Al2O3 composite sample calcinated at 500 °C for 3 h shows both the maximum adsorption capacity and photocatalytic activity. Nearly all of the initial methyl orange is removed from TiO2-Al2O3 composite after a certain time period. As compared with pure TiO2, photocatalytic activity and adsorption capacity of TiO2-Al2O3 composite are enhanced obviously.