Nature of the excited states of the rutile TiO2(110) surface with adsorbed water

We present an ab initio embedded cluster study of the ground and excited states for the rutile (1 1 0) surface with adsorbed water molecule. The calculated adsorption energies and geometries are compared with available experimental data. Upon photoexcitation, an electron–hole pair is created. We found that the electron is localized in the subsurface and thus cannot be directly involved in surface processes whereas the hole is localized on the surface oxygen atoms and enhances the radical character of the hydroxyl group. Our results support experimental suggestions that OH radical is the active species in photocatalysis on TiO2 surface. 2001 Elsevier Science B.V. All rights reserved.