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研究报告

Chiral TiO₂-based photocatalysts with visible light response and their photo-degradation of organic pollutants

摘要：通过空穴和自由基捕获剂的加入,首先研究了可见光激发下手性TiO₂复合光催化剂降解罗丹明B和四环素的机理. 结果表明,可见光激发TiO₂光催化剂降解罗丹明B和四环素的机理是相同的,其形成的光生空穴是降解有机物的关键影响因素.利用D型手性表面活性剂在低温时可以构建右旋非对称手性堆积结构的D-TiO₂. 这种非对称结构在介孔TiO₂内部引入氧空穴和Ti-N键,使D-TiO₂也具有显著的可见光响应和可见光降解活性. La³⁺ 或者Fe³⁺的掺杂几乎不影响催化剂的形貌及其TiO₂的结晶过程, 但可以在催化剂中形成光生空穴和电子的捕获中心,显著提升可见光激发下TiO₂催化剂中光生空穴和电子的分离率,从而增强催化剂对四环素的光降解活性.

Abstract：Via the addition of hole and free radical scavengers, the photo-degradation mechanism for rhodamine B and tetracycline by the chiral TiO₂ mesoporous composite photocatalysts was studied under the excitation of visible light. It was found that the chiral TiO₂ mesoporous photocatalyst can degrade rhodamine B and tetracycline under the same mechanism irradiated by visible light. And the photo-generated holes during light irradiation were the key factors that affecting the degradation for organic pollutants. The D-type chiral surfactant could be used to construct D-TiO₂ with a right-handed asymmetric chiral stacking structure at low temperature. This asymmetric structure introduced oxygen holes and Ti-N bonds into the mesoporous TiO₂, so that D-TiO₂ also had significant visible light response and good photo-degradation activity excited by visible light. The La³⁺ or Fe³⁺ doping hardly affected the morphology and the TiO₂ crystallization of the chiral TiO₂ mesoporous catalyst. However, the trapping center for the photo-generated holes and electrons could be formed in the catalyst, and the separation rate of photo-generated holes and electrons in the chiral TiO₂ mesoporous catalyst irradiated by visible light could be significantly improved, thereby enhancing the photo-degradation activity for tetracycline.