Influence of Fe-Doping on the Structural and Electronic Properties of the TiO<sub>2</sub> Anatase:Rutile
Ericson H. N. S. Thaines, Aline C. Oliveira, Leandro Aparecido Pocrifka, Hélio A. Duarte, Renato G. Freitas
Abstract
The Fe-doped anatase and rutile TiO 2 phases were investigated by using a combined experimental and theoretical approach. The Fe-doped phases were characterized by X-ray diffraction with Rietveld refinement. The band structure and projected density of state (PDOS) were fully characterized using DFT/plane-wave calculations on a supercell model with 48 atoms. The band gaps of 3.17 and 2.95 eV were estimated for the pure anatase and rutile TiO 2 phases. The band gap values decreased to 3.00 and 2.13 eV with Fe doping for anatase and rutile TiO 2 –Fe phases, respectively. The water-splitting reaction on the anatase (0 1 0) TiO 2 and TiO 2 –Fe surfaces was investigated. The quantum efficiency assessed by the transfer rate of electrons and holes increased with the presence of Fe in the TiO 2 structure. The initial steps of the reaction mechanism and the transition states were determined using the NEB (nudged elastic band) method considering the species involved H 2 O, OH •, and H + on the (0 1 0) TiO 2 surface. The activation energies of 0.29 and 0.08 eV were estimated for pure anatase TiO 2 and anatase TiO 2 –Fe structures. The DFT/plane-wave calculations on the synthesized Fe-doped material are predicted to improve its photocatalytic properties toward water splitting.