Au/TiO2复合物的制备、表征及其增强光催化灭菌活性

Preparation,characterization and enhanced photocatalytic sterilization activity of Au/TiO2 composite

为提升TiO2光催化活性克服其可见光响应能力差的问题,采用沉积-沉淀法制备了Au/TiO2复合物光催化剂,利用X射线衍射(XRD)、傅里叶红外光谱(FTIR)、X射线光电子能谱(XPS)、紫外-可见漫反射光谱(UV-vis DRS)、荧光发射光谱等对样品进行了表征。XRD、FTIR和XPS结果表明,Au/TiO2中TiO2为锐钛矿相且Au成功沉积至TiO2。UV-vis DRS和荧光发射光谱结果表明,适量Au修饰不仅能提高TiO2对可见光的吸收,还可促进TiO2光生电子-空穴对分离,有利于增强其光催化活性。自由基捕获实验证实,形成 OH的数量与光照时间成正比且 OH生成量越多,光催化活性越高。对比考察了Au/TiO2和TiO2在氙灯光源照射下对大肠杆菌的光催化杀灭作用,并探讨了Au负载量、光照时间、光照强度、光催化剂浓度等因素对灭菌性能的影响。结果表明:Au/TiO2的光催化灭菌活性优于TiO2,且与光照时间和光照强度均成正比;Au的适宜负载量为3%(质量分数);3%Au/TiO2在光照时间60min、光照强度7mW/cm^2、光催化剂浓度100μg/mL的条件下,对大肠杆菌的杀灭效率高达91.3%。

To overcome the poor visible light response of TiO2 and improve its photocatalytic activity,Au/TiO2 composite photocatalysts were prepared by deposit-precipitation method.The samples were characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),ultraviolet-visible diffuse reflectance spectroscopy(UV-vis DRS)and fluorescence emission spectrum.The results of XRD,FTIR and XPS showed that TiO2 in Au/TiO2 was anatase phase and zero-valence Au was successfully deposited on TiO2.The results of UV-vis DRS and fluorescence emission spectrum indicated that appropriate amount of Au modification could not only improve the absorption of visible light by TiO2,but also promote the separation of photogenerated electron-hole pairs of TiO2,which was conducive to enhance its photocatalytic activity.Free radical capture experiments confirmed that the amount of·OH formed was proportional to the irradiation time,and the more·OH formed,the higher the photocatalytic activity.The photocatalytic killing effects of Au/TiO2 and TiO2 on Escherichia coli irradiated by xenon lamp were compared.The influences of Au load,illumination time,illumination intensity and photocatalyst concentration on the sterilization performance were discussed.The results showed that the photocatalytic sterilization activity of Au/TiO2 was better than that of TiO2,and it was proportional to the illumination time and illumination intensity.The optimum loading of Au was 3%(mass fraction).Under the conditions of 60min illumination time,7mW/cm^2 illumination intensity and 100μg/mL photocatalyst concentration,the photocatalytic sterilization efficiency of 3%Au/TiO2 reached 91.3%.