Within an ab initio study, based on the application of Many-Body Perturbation Theory approaches on top of ground-state Density Functional Theory calculations, we study the optical behavior of the TiO${}_2$ anatase (001) surface. We focus on the (1 $\times$ 1) and the (1 $\times$ 4) reconstructions, both experimentally observed, which reveal a different optical response and an anisotropy, in the (001) plane, not present in the bulk phase. The determination of the spatial behavior of the electron-hole photoexcited couple provides a possible explanation of the observed enhanced photocatalytic activity of TiO${}_2$ anatase nanostructures with a high percentage of (001)-(1 $\times$ 1) exposed facets.

• Received 27 June 2011

DOI:https://doi.org/10.1103/PhysRevB.84.073404