Thus, the main objective to prepare such nanoscale systems is aimed at controlling their surface composition and particle morphology. Therefore, much attention has been focused on development of binary or ternary metal oxides as heterogeneous catalysts. The nature of active sites of solid acid catalysts is defined by mobile surface protons generating Brønsted acid sites and coordinately unsaturated cationic centers as Lewis acid sites. Combination of dissimilar oxides allows to create surface active sites, which are absent in individual components. Highly disperse (nanoparticulate) oxide composites are of great interest for individual applications not only as heterogeneous catalysts with an adjustable set and strength of surface active sites but also as a part of organic–inorganic composites and polymer fillers. The particle size distributions in aqueous media showed a tendency of increasing particle size with increasing TiO 2 content in the composites. Textural analysis shows that initial silica is mainly meso/macroporous, but composites are mainly macroporous. According to XPS data, Zr and Ti are in the highest oxidation state (+4). According to the Raman spectra, the bands specific for anatase are observed in TiZrSi2.
The samples calcined at 550 °С were amorphous as it was found from XRD data. Composites TiZrSi1 (TiO 2:ZrO 2:SiO 2 = 3:10:87) and TiZrSi2 (10:10:80) calcined at 1100 °С demonstrate the presence of t-ZrO 2 crystallites in TiZrSi1 and ZrTiO 4 phase in TiZrSi2.
It was revealed that the component ratio and calcination temperature affect the phase composition of nanocomposites.
#Casa xps peak fitting double intensity of one peak series
A series of TiO 2–ZrO 2/SiO 2 nanocomposites were synthesized using a liquid-phase method and characterized by various techniques, namely, nitrogen adsorption–desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, high-resolution transmission electron microscopy, and photon correlation spectroscopy (PCS).