Electronic Origin of the Surface Reactivity of Transition-Metal-Doped TiO₂(110)

Abstract

We investigate the surface reactivity of doped rutile M-TiO₂(110) (M = V, Cr, Mo, W, Mn, Fe, Ru, Co, Ir, and Ni) using density functional theory (DFT) and Hubbard-<i>U</i> corrected DFT calculations (DFT+<i>U</i> method). The oxygen adsorption bond, used as the surface reactivity measure, is stronger on the doped TiO₂ surfaces as compared with that on the undoped TiO₂ surface. We relate this increase in reactivity of the doped TiO₂ surfaces to the presence of localized surface resonances and surface states in the vicinity of the Fermi level. We find that the center of these localized states on doped TiO₂ is a good descriptor for the oxygen adsorption energy. The inclusion of the Hubbard-<i>U</i> correction to DFT barely modifies the oxygen adsorption energy on undoped TiO₂, whereas it destabilizes the oxygen adsorption energies on doped TiO₂ when compared with results from standard DFT. Nevertheless, we find that the oxygen adsorption energy trends predicted by a standard GGA-DFT functional are reproduced when the Hubbard-<i>U</i> correction is applied