A spectroscopic study of anatase properties. II. Characterization of a via-sulfate preparation

TiO2 (anatase), prepd. via a sulfate process was characterized by IR transmittance and UV, visible, and near-IR diffuse reflectance spectroscopy. The spectrum of surface OH groups and of undissociated coordinated water is quite different from that of a via chloride prepn. and from that of most TiO2 prepns. reported in the literature. The redox properties are also different from those of the via chloride prepn. S-contg. impurities, which are quite abundant in samples taken in the early stages of prepn., occur mainly in the form of surface sulfates. These possess variable structure and are highly sensitive to the surface hydration degree and, more in general, to the overall polarity of the surface layer