Mixed Dissociative and Molecular Water Adsorption on Anatase TiO₂(101)

Abstract

The adsorption properties of water on the stoichiometric (101) surface of anatase TiO 2 in the temperature range 160–400 K has been studied by synchrotron radiation core level photoelectron spectroscopy. O 1s spectra give clear evidence for the formation of a first layer of water that comprises both H 2 O and OH. The composition is 0.77 ± 0.05 ML H 2 O and 0.47 ± 0.05 ML OH. Decreasing the coverage by heating leads to a decreased H 2 O/OH ratio. The results are very similar to those recently reported for water on rutile TiO 2 (110) and show that the previously proposed model of molecular adsorption only on anatase TiO 2 (101) must be revised.