不同结构TiO_2-ZnO异质复合膜光催化活性的研究

Study on Photocatalytic Activity of TiO_2-ZnO Heterojunction Composite Films with Different Structure

采用多靶磁控溅射离子镀技术制备TiO2-ZnO和(TiO2-ZnO)/TiO2两种不同结构的复合薄膜。研究薄膜在pH值分别为5、7和9时对甲基橙的降解,并结合薄膜光催化实验后的透光率、表面形貌和电化学腐蚀性能,探讨TiO2顶层对TiO2-ZnO异质复合薄膜光催化活性的影响。结果表明:两种薄膜的光催化活性均在酸性中最好,依次为碱性和中性,但(TiO2-ZnO)/TiO2薄膜的降解率和降解速率始终高于TiO2-ZnO薄膜,且酸、碱性环境下更明显。光催化实验后,(TiO2-ZnO)/TiO2薄膜表面无变化,TiO2-ZnO薄膜出现明显的腐蚀、溶解形貌,且薄膜透光率在不同环境中的变化相差4～5倍。在不同pH值的3.5wt%NaCl溶液中,(TiO2-ZnO)/TiO2复合薄膜的腐蚀电位和腐蚀电流均优于TiO2-ZnO薄膜。由于TiO2顶层良好的耐酸碱腐蚀性能,(TiO2-ZnO)/TiO2薄膜在pH值较大范围的溶液中表现出更好的光催化活性。

Two different structure composite films of TiO2-ZnO and （TiO2-ZnO）/TiO2 were prepared by multi- target magnetron sputtering ion plating technique. The photocatalytic activity were analyzed in methyl orange solution at pH 5, 7 and 9, respectively. The effect of top TiO2 layer on the photocatalytic activity of TiO2-ZnO heterojunction composite film were discussed with the light transmittance, surface morphology, and the electrochemical corrosion property. The results show that the photocatalytic activity of two different structure films were all the best in the acidic methyl orange solution, and followed by alkaline and neutral. The discoloration rate P and degradation rate K of （TiO2-ZnO）/TiO2 film were greater than TiO2-ZnO film all the time, and the difference was more distinct in acidic or alkaline solution. After the photocatalytic test, there was almost no change on the （TiO2-ZnO）/TiO2 film surface, but the corrosion and dissolving morphology emerged on TiO2-ZnO film clearly. The change in light transmittance differed 4-5 times between the two different films. In the 3.5wt% NaCI solution of different pH values, the corrosion potential and corrosion current of （TiO2-ZnO）/TiO2 film were all superior to TiO2-ZnO film. Due to the good resistance to acidic and alkaline of TiO2, the （TiO2-ZnO）/TiO2 film showed a better photocatalytic property in a wide range of pH.