Morphology, Surface Structure and Water Adsorption Properties of TiO Nanoparticles: A Comparison of Different Commercial Samples.

Water is a molecule always present in the reaction environment in photocatalytic and biomedical applications of TiO and a better understanding of its interaction with the surface of TiO nanoparticles is crucial to develop materials with improved performance. In this contribution, we first studied the nature and the surface structure of the exposed facets of three commercial TiO samples (i.e., TiO P25, SX001, and PC105) by electron microscopy and IR spectroscopy of adsorbed CO. The morphological information was then correlated with the water adsorption properties, investigated at the molecular level, moving from multilayers of adsorbed HO to the monolayer, combining medium- and near-IR spectroscopies. Finally, we assessed in a quantitative way the surface hydration state at different water equilibrium pressures by microgravimetric measurements.