Depletion of conduction band electrons in TiO2 by water chemisorption – IR spectroscopic studies of the independence of Ti–OH frequencies on electron concentration

The chemisorption of water at 300 K onto reduced TiO2 produces both adsorbed Ti–OH groups and chemisorbed water. During the adsorption of H2O, the concentration of conduction band electrons is found to decrease as measured by transmission infrared spectroscopy. The TiO2 electron depletion process occurs predominantly during the first stages of water adsorption, probably due to Ti–OH species formation. It is also found that the infrared spectrum of Ti–OH groups in the ν(OH) region is not influenced by the electronic state of the TiO2 surface, comparing TiO2 containing different concentrations of conduction band electrons.