Preparation And Photoelectric Properties Of Nano-CeO₂ Composites

TiO2 is an excellent semiconductor material that has a wide applications in solar cell, photocatalysis, and air purification. As well known, rare earth element has a unique 4f sub-layer electronic structure that can improve the performance of semiconductor composites. Recently the photocatalysis of the rare earth doped semiconductor materials has mainly been studied, but their electrochemical properties have rarely been reported.In this paper, various CeO2 composites were prepared by using sol-gel method, and the structure and composition of the products were characterized by Scanning Electron Microscope (SEM), X-ray Diffraction (XRD), Infrared Spectrometer (FT-IR), and X ultraviolet-visible Spectroscopy (UV-vis). The formation mechanism of the composites was discussed, and the electrochemical luminescence property and photocatalysis of the products were studied.Our main work as follows:1. The preparation and electrochemical property of TiO2/CeO2 composite filmsFirst, the TiO2 sol-gel prepared by using the sol-gel process was doped with a certain amnount of Ce (NO3) 3·6H2O. Then, the TiO2/CeO2 composite films were prepared by dipping lifting method and calcining. The morphology and crystal structure of films as-obtained were characterized by SEM, XRD, UV and FTIR. The electrochemical luminescence (ECL) of the composite films was studied by cyclic voltammetry (CV), and the effect of the electrolyte solution with different pH on ECL was discussed. The results show that the ECL property of the TiO2/CeO2 composite films has been greatly improved, comparing to the pure films. The calcining temperature affected the morphology and electrochemical property of composite films. When calcinated at 200℃for 1h and then at 450℃for 1h, the composite film as-obtained has a excellent ECL property. 2. The preparation and electrochemical property of TiO2/CeO2 composite powderWith Ce (NO3) 3·6H2O as cerium source, the CeO2 yellow powder was first obtained through the ammonia precipitation method. Then, the TiO2 sol formed by sol-gel process was added a certain amount of the CeO2 powder. Finally, the TiO2/CeO2 composite powder was obtained by drying and calcining the sol. The products as-prepared were characterized by SEM and XRD, and their ECL property was studied by cyclic voltammetry. The effect of scanning range, the pH of electrolytic solution and adhesive nafion on ECL was discussed. The results show that the different ECL curves was obtained in different scanning range or with different pH solution. With appropriate amount nafion, the powder can be solidly fixed on the surface of glassy carbon electrode. Significantly, the ECL1 and ECL2 peaks produced by TiO2/CeO2 composite powder were studied by controlling potential exerted on the work electrode. The result shows that the ECL1 is electrochemical luminescence peak and ECL2 involves some chemiluminescence component.3. The preparation and photocatalysis of CeO2/GO composite powderWith Ce (NO3)3·6H2O as cerium source, the CeO2 yellow powder was first obtained through the ammonia precipitation method. Then, the CeO2/GO composite powder was prepared by mixing graphene oxide and CeO2 powder. The structure and composition of the products were characterized by SEM, XRD and UV-vis. The photocatalytic activity of the CeO2/GO composite power was studied by photodegradating organic methylene blue with sun light. The results show that the GO can enhance the photocatalysis of the composite powder.