Physicochemical and Photocatalytic Properties of Nanosized Titanium Dioxide Deposited on Silicon Dioxide Microspheres

摘要

The synthesis of SiO_2 core–TiO_2 shell composites from a titanium dioxide sol and a suspension of microspherical silicon dioxide is described. The main factors ensuring the formation of a composite with a preset morphology are the size and charge of the TiO_2 sol particles (10–45 nm) and silicon dioxide core particles (300–700 nm), the pH values of the suspensions of the starting components and the resulting composite, and the proportions and way of mixing of the silicon- and titaniumcontaining components. The SiO_2 core–TiO_2 shell composites show high photocatalytic activity in the degradation of Rhodamine FL-BM dye (rate constant of k = 0.0813 min~(–1)) and are much more active than precipitated TiO_2 powder (k = 0.0022 min~(–1)). The activity of the composite is determined by the calcination temperature (700–800℃), by the proportion and accessibility of the active component (TiO_2), and by the presence of a dopant (P_2O_5).