| Facing with the intractable pollution attributed from the population increase and urbanization expansion, it is an urgency to search green and efficient methods for environmental modification with absence of secondary pollution. The photo catalytic feature of titanium dioxide (TiO2) is amazing for its high oxidizability, eco-friendly and solar energy motivated and these enable the application of TiO2 for the treatment of the industrial organic waste water. However, for the economical consideration, the TiO2 particle must be recycled after utilization and this process is complicated and likely to lead a loss of the particle. Moreover, the utilization efficiency of solar energy is considerably restrained since TiO2 can be only inspired by ultra-violet (UV) light. Besides another influence on the photocatalytic ability of TiO2 is that the recombination rate of the electron hole pair exceeds the separation rate. Aiming at the problems listed above, a developed preparation of T1O2 membrane was studied in this paper. The form of membrane other than particle sets a limitation of the mobility of TiO2 catalyst and the loss in recycle stage can be avoided. Secondly TiO2 can be modified to expand the motivation wavelength range and improve the absorbing efficiency of solar energy. Lastly photocatalytic process was externally assisted by bias technique and this advanced the separation ratio of the electro hole and catalytic efficiency.The TiO2 membrane was prepared by spraying sol-gel onto the FTO glass, and P-type semiconductor Cu2O was loaded on the N-type TiO2 via hydrothermal method to form compounded membrane (Cu2O/TiO2). Subsequently the MB photocatalytic degradation experiment was carried out with Cu2O/TiO2 as positive electrode and Ti film as negative electrode.According to the characterization of SEM, XRD and UV-vis etc., the pure TiO2 film had a clear surface structure that irregular fractures and agminated bulks of TiO2 could be found. And this leads a relatively large specific surface area. The TiO2 is of anatase crystal form with high photocatalytic activity. At the MB degradation experiment, the highest degradation efficiency of 70% was reached with initial MB concentration of 10 ppm and solution pH of 8. For the characterization of Cu2O/TiO2 compounded membrane, massive Cu2O net was confined within the gaps of the bulk TiO2 so that the original structure of TiO2 was retained. And the crystal form of TiO2 maintained still as anatase. The UV-vis results showed that light absorption range of coupled film has a tendency of red shift which caused a wider absorption region and higher solar energy utilization. The highest degradation efficiency of 80% was reached with initial MB concentration of 10 ppm and solution pH of 8. And the highest degradation efficiency at electrically assisted photocatalysis was over 80% under the voltage of 0.8 V and pH of 10 even the film surface was smaller compared to the pure photocatalitic experiment.In this paper we found that the photocatalytic activity of coupled film (Cu2O/TiO2) was higher than pure TiO2 film and it could be enhanced by the external bias field. Thus it comes to the conclusion that the modification of TiO2 and the application of electrically assisted photocatalysis can remarkably improve the photocatalytic activity of TiO2, and this provides valuable information for the practical application of TiO2 material in the field of organic pollutant degradation. |
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