Effect of Fe Doping Concentration on Photocatalytic Performance of CeO2 from DFT Insight into Analysis

A series of CeO2 based materials are analyzed using first-principles calculation. After geometry optimization, the calculated parameter of Ce32O64 is in good agreement with the experimental and theoretical results. The lattice constant of doped materials becomes increasingly smaller with the introduction of more Fe doping into the lattice owing to the small radii of impurity atoms. Other data relate to increase or decrease to some extent. As for electronic property, the energy band structure and partial density of states are explored and discussed. Due to the enhancement of the degree of hybridization between O atoms and metal atoms, there is a narrower band gap in Fe doped materials, indicating that lower energy can promote and achieve electronic transition from the valence band to the conduction band. Through the complex dielectric function composed of the real part and the imaginary part, the extinction coefficient, it is observed that they are responsive to light and electronic transition under visible light irradiation. On the other hand, we predict the photocatalytic behavior by discussing the extinction coefficient. Besides, the optical absorption spectrum and optical band gap are analyzed to further observe performance in photocatalysis. It is found that doping causes first the red shift of the absorption edge and then results in the red shift and enhancement of photocatalytic performance, which is consistent with our prediction. In addition, E-opt indicates that Fe is beneficial for the activity of CeO2. The atomic number ratio of 3:1 (Fe:Ce) shows superior behavior compared to other materials.