Preparation And Photocatalytic Performance Of CuCrO₂/TiO₂ Composite Photocatalysts

Photocatalytic technology is a new practical technology, which can degradate organic and toxic substance by absorbing solar energy directly. It is a kind of green treatment technology which can both protect environment and save energy. Ti O2 is proven a champion in the photocatalyst industry because of its high efficiency and earlier research. However, it still need much improvement due to its wide band gap and low quantum efficiency. As a result, it is of great significance to improve the photocatalytic performance by the method of modifying TiO2.The idea here is based on the theory that compound of different semiconductors can improve the performance of photocatalysts. We intend to employ the p-n heterojunction structure to guide the flow of elentrons and holes, strength the separation efficiency of electron-hole pairs and quantum efficiency, enhance the photocatalytic performance of TiO2 greatly in the end. CuCrO2 nanocrystals and TiO2 nanorod-array film were both synthesized by facile hydrothermal method by different raw materials. We also optimized the synthesis condition of TiO2 film. CuCrO2/TiO2 photocatalysts were fabricated by simple spin-coating method and soaking method for the first time. By the characterization of XRD,SEM,TEM,XPS,PL, photocurrent and experiment of degradation of methylene blue aqueous solution, we found that the modification of TiO2 is positive and effective. The discuss about synthesis condition such as spin-coating, soaking and heat treatment make it more clear that the deposit amount and heat treatment system play important roles on the photocatalytic performance. For spin-coating, the sample fabricated at speed of 5000r/min for 5 times(20s each time) using 0.50g/L CuCrO2 suspension own the best photocatalytic activity, the efficiency and reaction rate is 85.3% and 0.236h-1, about 1.14 times and 1.39 times higher than that of pure TiO2. As for soaking method, the best performance is 82.2% and 0.216h-1, 1.10 times and 1.27 times higher than that of pure TiO2, appear at the condition of using 0.50g/L CuCrO2 suspension and soak for 32 h. The analysis of test and characterization identify the improvement come from the p-n heterojunction structure between CuCrO2 nanocrystals and TiO2 nanorods. Because the inner electric field can guide electrons flow to conduction band of TiO2 and holes flow to valence band of CuCrO2. The result is that electron-hole pairs were separated more effectively through this way.Our experiments have confirmed the availability of p-n heterojunctions to improve the photocatalytic activity of TiO2. When the preparation method is more accurate and CuCrO2 content can be controlled quantificationally, higher photocatalytic perfoamance can be achieved. It is expected the strategy of p-n heterojunction for enhancing photocatalytic activity can have considerable impact to promote the development of high efficient photocatalyst and industrial application for degrading pollutant, treating waste water and other environmental protection fields.