文摘
The geometrical, electronic and energetic properties of the dissociative (1×2) adsorption of H2O on the rutile TiO2(110) surface are calculated by applying the full potential linearized plane wave method within the local density approximation. Two possible (1×2) adsorption geometries are investigated. We find a general reduction of the bond lengths at the surface and an inwards relaxation of the surface plane. Whereas the O–H bond lengths are very similar for both geometries and comparable to that of the free H2O molecule, the corresponding Ti–O bond lengths differ by 0.25 Å, expressing the amphoteric character of the OH groups. Concerning their ground-state energies, both adsorption geometries are practically equal. Additional OH surface peaks appear in the density of states, lowered by about −2 eV from the main parts of the O s and p bands of the clean surface. Upon adsorption, the lowest Ti d-like states of the conduction band of the clean surface become occupied. Compared with the clean surface, the work function is strongly reduced by about 3 eV.
