Oxygen vacancy and Ce ion co-synergize to enhance the photocatalytic degradation performance of FeTiO3: An experimental and DFT study

Abstract

Doping the iron titanate (FeTiO3) with rare earth element is considered as an effective method of enhancing its photocatalytic performance. In this work, the novel FeTiO3 doped with cerium (Ce) (Ce/FeTiO3) photocatalysts were designed and synthesized using the sol–gel method. The 10 mol% Ce/FeTiO3 photocatalyst displays excellent photocatalytic performance for degrading the tetracycline hydrochloride (TCH), methylene blue (MB) and brilliant blue (BB). The degradation efficiencies are 97.50 % (TCH), 95.40 % (MB), and 84.60 % (BB), respectively, and the degradation rate constants (k) are 3.68, 2.91, and 7.12 times that of pure FeTiO3. Density functional theory (DFT) calculations were used to study the photocatalytic degradation mechanism in depth. The results show that the content of oxygen vacancy is increased and the oxygen vacancy formation energy is significantly increased from 2.25 eV to 6.97 eV after doping the Ce ion, which can provide more active sites to degrade pollutants and enhance the photocatalytic performance of the FeTiO3. Furthermore, the Ce 4f orbital can narrow the bandgap and form the impurity level to capture the photoexcited electron, inhibiting the recombination rate of photocarriers in FeTiO3. This work is expected to provide a valuable insight into the Ce doped FeTiO3 photocatalyst, which is conductive to expanding the practical applications of FeTiO3-based photocatalyst.