In situ Fenton reagent generated from TiO2/Cu2O composite film:: A new way to utilize TiO2 under visible light irradiation

TiO2/CU2O composite is prepared by a simple electrochemical method and coated on glass matrix through a spraying method. The obtained composite is characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of TiO2/CU2O composite films with different ratio of TiO2 and Cu2O on photodegradation of the dye methylene blue under visible light is investigated in detail. It is found that the photocatalytic activity of TiO2/C2O composite film with the presence of FeSO4 and EDTA is much higher than that for the similar system with only TiO2 and Cu2O film respectively. Without the presence of FeSO4 and EDTA, there is no degradation for methylene blue. The exploration of the optimized parameters for the degradation of methylene blue by using TiO2/Cu2O composite film as catalyst under visible light was also carried out. The most significant factor is the amount of TiO2 in the composite, and the second significant factor is the concentration of FeSO4. During the degradation of methylene blue under visible light, TiO2/Cu2O composite film generates H2O2, and Fenton regent is formed with Fe2+ and EDTA, which is detected in this study. The mechanism for the great improvement of photocatalytic activity of TiO2/Cu2O composite film under visible light is proposed by the valence band theory. Electrons excitated from TiO2/Cu2O composite under visible light are transferred from the conduction band Of Cu2O to that of TiO2. The formed intermediate state of Ti3+ ion is observed by X-ray photoelectron spectroscopy (XPS) on the TiO2/Cu2O composite film. Additionally, the accumulated electrons in the conduction band of TiO2 are transferred to oxygen on the 2TiO(2) surface for the formation of O2- or O-2(2-), which combines with H+ to form H2O2. The evolved H2O2 with FeSO4 and EDTA forms Fenton reagent to degrade methylene blue. Compared to the traditional Fenton reagent, this new kind of in situ Fenton reagent generated from TiO2/Cu2O composite film does not need to supply H2O2. It is expected to be easily recycled, which may reduce second pollution and the cost of wastewater treatment. Moreover, this TiO2/CU2O composite film with FeSO4 and EDTA provides a new way to take advantage of TiO2 under visible light.