炭包覆TiO_2复合物对低浓度苯的光催化降解(英文)

Carbon-coated TiO_2 composites for the photocatalytic degradation of low concentration benzene

通过将TiO2粉末和聚乙二醇混合,随后在氮气气氛下热处理合成了炭包覆TiO2。利用粉末X射线衍射、紫外-可见漫反射光谱、透射电子显微镜和氮吸附对炭包覆TiO2复合物样品进行了表征,并研究了其对浓度为～1.2×10-5苯的光催化活性。结果表明:炭包覆量受热处理温度和聚乙二醇用量的影响,随着温度的升高和聚乙二醇量的减少而减少;TiO2的结晶度随着温度的升高而提高,但是炭包覆对TiO2晶体的生长有抑制作用。炭包覆锐钛矿样品比纯TiO2表现出对苯更高的光催化活性,这是由于炭吸附作用导致锐钛矿颗粒周围的苯浓度增加以及包覆炭可导致电荷的有效分离;另一个原因是锐钛矿相结晶度的提高。因此,要获得对苯具有高光催化活性的炭包覆TiO2需要综合考虑碳含量和锐钛矿晶体结构。

Carbon-coated TiO2 was synthesized by mixing TiO2 powders and polyethylene glycol,followed by heat treatment in nitrogen atmosphere.All samples were characterized by powder X-ray diffraction,UV diffuse reflectance spectroscopy,high-resolution transmission electron microscopy,and nitrogen adsorption.The photocatalytic activity of carbon-coated TiO2 for benzene degradation was investigated with a benzene concentration of ~1.2×10-5.Results showed that the residual carbon content was influenced greatly by heat treatment temperature（HTT）and the amount of PEG,which decreased and increased with increasing the temperature and the amount of PEG,respectively.The crystallinity of TiO2 was improved when the HTT increased.However,the carbon residue had an inhibition effect on the crystal growth of TiO2.The carbon-coated anatase samples were shown to exhibit higher photocatalytic activities than the pristine TiO2 because of the adsorption enrichment of benzene by carbon around the anatase particles and of the effective charge separation due to the electronic conduction of carbon.Another important factor affecting photocatalytic activity was the crystallinity of the anatase phase.High photocatalytic activity for benzene requires a balance between the carbon content and the anatase crystalline structure.