A spectroscopic study of anatase properties. I. Characterization of a via-chloride preparation

TiO2 anatase, prepd. via a chloride process, was characterized by IR transmittance and UV, visible near IR diffuse reflectance spectroscopy. The IR spectrum of surface OH groups and that of coordinated, undissociated, water is not characteristic of the anatase phase. Nor are they characteristic of the prepn. itself, but vary on passing from the virgin to the rehydrated material. These features are ascribed to a variable termination of crystallites. Redox properties are quite variable, as shown by the spectral features of 3 absorptions in the visible-IR range. Traces of Cl impurity strongly participate in the redn. processes, but the via-chloride prepn. is quite reducible even in the absence of residual Cl ions. The absorption caused by sample redn. are affected to a variable extent by various adsorbates.