“In situ” preparation of a TiO2/Eu2O3 composite film upon Ti alloy substrate by micro-arc oxidation and its photo-catalytic property

The TiO2/Eu2O3 composite film was prepared by using a micro-arc oxidation (MAO) technique. The experimental results showed that the photo-catalytic performance of the TiO2/Eu2O3 composite film exhibited twice higher than that of the film without Eu2O3 additive. The reason was that the ion Eu3+ in Eu2O3 had an incomplete 4f orbital track and an empty 5d orbital track, which tended to produce multi-electron configuration, and therefore could effectively inhibit the recombination of photo-generated electrons and holes. In addition, the ground-state energy was close to the excited-state energy in the ion Eu3+, which enhanced the transition of f-electron from the ground-state to the excited-state under the visible light irradiation, and then exhibited a higher absorption in the visible light range.