Ti基底的预处理对TiO2光催化膜长期稳定性的影响

研究了Ti基底的预处理方法对其负载的TiO2薄膜光催化活性和长期稳定性的影响.分别采用扫描电子显微镜、X射线光电子能谱、X射线衍射和电化学交流阻抗谱对样品进行了表征,并考察了Ti基底负载的TiO2膜光催化降解模型污染物苯甲酰胺和活性艳红X-3B的活性.结果表明,采用普通Na2CO3预处理Ti基底时制得的TiO2膜层较疏松,并且由于Ti基底自身生成的TiO2钝化膜层不断生长而导致其负载的TiO2光催化膜层明显脱落流失,该TiO2膜在水中浸泡60 d后即完全失活.而在乙二酸活化法预处理的Ti基底上能制备出致密的TiO2光催化膜,可抑制Ti基底自钝化膜的生长,从而显著提高了负载TiO2光催化膜的抗脱落流失能力,在水中浸泡280 d后,其光催化活性仍不低于新制备样品活性的70%;而且在35 d的活性艳红完全脱色连续流实验中,该TiO2光催化膜基本未发生失活现象.

Influence of Pretreatment of Titanium Substrate on Long-Term Stability of TiO2 Film

TiO2 films coated on titanium substrates pretreated using different methods were prepared and characterized by scanning electron microscopy,atomic force microscopy,X-ray diffraction,and electrochemical impedance spectroscopy.The results indicated that the TiO2 film coated on the substrate pretreated with oxalic acid(TiO2/Ti-OC) was tightly,whereas the film coated on the substrate pretreated with sodium carbonate solution(TiO2/Ti-SC) was loose.The catalytic activity of the TiO2/Ti-OC film for the degradation of benzamide remained up to 70% even after dipping in deionized water for 280 d,whereas the TiO2/Ti-SC film lost its photoactivity after dipping in water for 60 d.The deactivation of the catalyst was attributed to the flaking of the coated TiO2,which was caused by the continuous growth of the passive film between the substrate and coated catalyst.Oxalic acid pretreatment could largely prevent the passive film from growing on the substrate and therefore greatly increased the stability of the catalyst during a long-term running.In a 35 day test of continuous declorization of aqueous reactive brilliant red X-3B solution,TiO2/Ti-SC exhibited very high photocatalytic activity and stability.