Synthesis of CaTiO3 and CaTiO3/TiO2 nanoparticulate compounds through Ca2+/TiO2 colloidal sols: Structural and photocatalytic characterization

CaTiO3 and CaTiO3/TiO2 nanocompounds have been synthesized through a colloidal sol-gel route using Ca2+/TiO2 nanoparticulate sols. The peptization time was determined so that as higher is the Ca2+ concentration, shorter is the peptization time. The obtained cryogels from the respective sols were calcined at different temperatures (300-900 °C) and the structural and morphological changes were characterized mainly by X-ray diffraction and transmission electron microscopy. In all cases, the formation of the CaTiO3 phase was observed after calcination at temperatures as low as 500 °C. Mesoporous cryogels with nanoparticles with sizes below 50 nm were obtained and their photocatalytic activity changes as a function of the calcination temperature and the applied wavelength were determined. Quantum yield values revealed that either CaTiO3 or the CaTiO3/TiO2 (0.4 M ratio) compound can be chosen as the most efficient photocatalyst at higher calcination temperatures and longer wavelengths, while TiO2 is more effective at low calcination temperatures and shorter wavelengths.