First-principles study of the adsorption of CO onTiO2(110)

Abstract

The adsorption of CO on ${\mathrm{TiO}}_{2}(110)$ is investigated using the full-potential linearized-augmented-plane-wave method. The equilibrium structures of the clean and adsorbed ${\mathrm{TiO}}_{2}(110)$ surfaces are optimized through total-energy and atomic force calculations. Two geometries of CO absorption, namely, OC-Ti and CO-Ti, were considered. It is found that the former orientation is preferred. The calculated adsorption energy and redshift of the CO stretch frequency based on the local-density approximation are 0.79 eV/molecule and 23 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$, respectively. The gradient corrections reduce the ${\mathrm{C}\mathrm{O}\ensuremath{-}\mathrm{T}\mathrm{i}\mathrm{O}}_{2}$ binding energy to 0.25 eV/molecule. CO interacts with the ${\mathrm{TiO}}_{2}(110)$ substrate mainly via its 5\ensuremath{\sigma} state. Significant charge redistribution is involved in the ${\mathrm{C}\mathrm{O}/\mathrm{T}\mathrm{i}\mathrm{O}}_{2}(110)$ interaction, which changes the Coulomb potential and subsequently causes large shifts in the core and valence states of the CO adsorbate.