Introduction of peroxo groups into titania: preparation, characterization and properties of the new peroxo-containing phase

Abstract

A new phase, where peroxo groups are incorporated into titania particles, along with anatase and hydrated η-TiO₂ with peroxo groups on the surface of titania nanoparticles were prepared by introduction of H₂O₂ into reaction mixtures while synthesizing TiO₂ from TiOSO₄ or by cold impregnation of pre-synthesized TiO₂. The samples were studied by a range of methods (classical and synchrotron-radiation X-ray powder diffraction, small-angle X-ray scattering, high-resolution scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray absorption spectroscopy, IR and Raman spectroscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance and absorption spectroscopy, DSC). The [TiO_x(O₂)_2−x(H₂O)_m] phase was first structurally characterized and compared to η-TiO₂. Most samples of H₂O₂-sensitized TiO₂ discolor methyl orange under visible light irradiation faster than commercial Hombikat UV100 treated with H₂O₂. The activity of the samples strongly relating to their phase composition was associated with the existence of a large amount of titanium peroxo complexes along with formation of mixed-phase samples.