Doping and transformation mechanisms of Fe3+ ions in Fe-doped TiO2

Abstract

A series of Fe-doped TiO₂ samples with different concentrations of Fe³⁺ ions annealed at different temperatures were prepared using a sol–gel method. For Fe-doped TiO₂, the existing states of Fe³⁺, the transformation of these existing states and the phase transition are investigated. It is revealed that the existing states of Fe³⁺ and the transformation of these existing states (substitutional Fe³⁺, α-Fe₂O₃ and Fe₂TiO₅) are closely related to the annealing temperature and the concentration of Fe³⁺. The anatase–rutile (A–R) transition is promoted by the substitutionally doped Fe in the TiO₂ lattice. In addition, the Fe-doped TiO₂ with a high calcination temperature (800 °C) and high doping concentration (x > 20) shows obvious ultrasonic piezoelectric catalytic activity for the reduction of CO₂ to CH₄. This work may be useful in understanding the doping mechanisms of Fe-doped TiO₂, and the fabrication of new catalytic materials.