Oxygen vacancy related distortions in rutile TiO2 nanoparticles: A combined experimental and theoretical study

The effects of doubly ionized oxygen vacancies (V-O(2+)) on the electronic structure and charge distribution in rutile TiO2 are studied by combining first-principles calculations based on density functional theory and experimental results from x-ray photoelectron and x-ray absorption measurements carried out in synchrotron facilities on rutile TiO2 nanoparticles. The generalized gradient approximation of the Perdew-Burke-Ernzerhof functional has demonstrated its suitability for the analysis of the V-O(2+) defects in rutile TiO2. It has been found that the presence of empty electronic states at the conduction band shifted similar to 1 eV from l(2g) and e(g) states can be associated with local distortions induced by V-O(2+) defects, in good agreement with Gauss-Lorentzian band deconvolution of experimental O K-edge spectra. The asymmetry of t(2g) and e(g) bands at the O-K edge has been associated with V-O(2+), which can enrich the understanding of studies where the presence of these defects plays a key role, as in the case of doped TiO2.