纳米TiO2/聚氯乙烯共轭衍生物复合材料的制备及可见光催化性能

聚氯乙烯（PVC）在270℃真空环境中经热处理脱除HCl得到具有共轭结构的PVC衍生物（CDPVC）。纳米TiO₂与CDPVC （质量比为2∶1）经高能球磨复合得到纳米TiO₂/CDPVC复合材料。采用TEM、XRD、XPS、FTIR、SEM和Raman等对纳米TiO₂/CDPVC复合材料进行了分析表征，并采用罗丹明B （Rh B）的光催化降解反应和K₂Cr₂O₇的光催化还原反应评价其可见光催化活性及稳定性。结果表明，TiO₂与CDPVC经高能球磨复合后形成了Ti—O—C结构，该结构有利于提高纳米TiO₂/CDPVC复合材料的可见光吸收能力和光生电子/空穴分离效率。与纳米TiO₂和普通研磨的TiO₂-CDPVC相比，纳米TiO₂/CDPVC复合材料具有较高的可见光催化活性和良好的可见光催化稳定性。其可见光催化机制是CDPVC吸收光子产生光生电子-空穴对，并容易将光生电子注入到TiO₂的导带中，CDPVC内光生电子和TiO₂导带上的光生电子（e_CB-）被吸附在材料表面上的氧捕获产生·O₂-自由基，·O₂-自由基可以直接降解RhB分子，直至最后降解生成H₂O和CO₂。 

Preparation and visible-light photocatalytic performances of nano TiO2/polyvinyl chloride conjugated derivative composite

Polyvinyl chloride (PVC) was heat-treated in a vacuum at 270℃ to prepare a partly conjugated derivative (CDPVC) through a reaction of remove HCl. The nano TiO₂/CDPVC composite was prepared by compounding commercial TiO₂ and CDPVC with the mass ratio of 2:1 in a high-energy ball-miller, and was characterized by TEM, XRD, XPS, FTIR, SEM and Raman, et al. The photocatalytic degradation of rhodamine B (Rh B) and the photocatalytic reduction of K₂Cr₂O₇ were used to evaluate the visible photocatalytic activity and stability of the nano TiO₂/CDPVC composite. The results show that the structure of Ti-O-C formed by compounding TiO₂ and CDPVC in a high-energy ball-miller, which is advantageous to the improvement in both visible-light absorption capacity of the nano TiO₂/CDPVC composite and separation efficiency of photogenerated electron/hole pairs. Compared to nano TiO₂ and TiO₂-CDPVC (an ordinary product after grinding TiO₂ and CDPVC), nano TiO₂/CDPVC composite exhibits the higher visible-light photocatalytic activity and excellent stability. The visible-light photocatalytic mechanism can be proposed that CDPVC adsorbs photos to produce photogenerated electron-hole pairs, and the photogenerated electrons can be easily injected into the conduction band of TiO₂. The photogenerated electrons (e_CB^-) in CDPVC and conduction band of TiO₂ can be captured by oxygen on the surface of the TiO₂/CDPVC composite to form·O_-² radicals, and·O_-² radicals can directly degrade rhodamine B molecules even to produce H₂O and CO₂.