Synthesis and optical properties of mesoporous MCM-41 containing doped TiO2 nanoparticles

Nanosized TiO2 is a kind of high-performance and functional inorganic material, the widespread use of TiO2 is impaired by some defects of its structure, wide band gap (3.2 eV), and agglomeration easily occurred during the synthesis process. Uniform ordered channels of mesoporous materials, such as MCM-41, can control the particle size of TiO2 and efficiently prevent particles from agglomeration. Tetraethylorthosilicate (TEOS) and tetrabutyl titanate were used as the silica source and Ti source respectively to synthesize the TiO2/MCM-41 (TM) doped with different ions. MCM-41 was synthesized using a hydrothermal route; metal ions were incorporated into the pore channels of MCM-41 via a sol–gel method. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), ultraviolet–visible (UV–vis) spectrophotometry, N2 adsorption–desorption measurements and X-ray photoelectron spectroscopy (XPS) confirmed the incorporation of TiO2 nanoparticles inside the pores of the mesoporous MCM-41 host without destroying its integrity. Specific surface area of TM composites increased, but the pore size and the pore volume decreased compared with that of pure MCM-41. The UV–vis spectra demonstrate that all the absorbance peaks of TM composites have a blue shift. The absorbance peaks of TM composites doped with different metal ions shift again. Ce-doped TM shows red shift markedly, which provides the possibility for preparing visible-light reactive photocatalyst.