Shock Synthesis of N-Doped Titania and Its Photocatalytic Activity under Visible Irradiation
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摘要: 冲击相变及冲击诱导化学反应可导致材料的物理、化学性能发生显著改变。采用炸药爆轰驱动飞片高速碰撞产生冲击波的方法，对富氮掺杂物双氰胺（C2N4H4）与P25 TiO2或偏钛酸（H2TiO3）的粉末混合物进行冲击加载，对回收产物进行X射线粉末衍射、透射电子显微镜、X光电子能谱、比表面积及紫外-可见漫反射光谱表征，通过亚甲基蓝和罗丹明B评价了回收产物的可见光催化降解活性。结果表明：以P25 TiO2为原料的冲击氮掺杂浓度可达8.88%，掺杂样品具有明显的可见光吸收，能带宽度减小到1.75 eV，样品中形成了少量Srilankite高压相；而以偏钛酸为原料的冲击氮掺杂浓度为3%～4%，能带宽度变化较小，但是由于其独特的冲击脱水膨胀机理，比表面积剧增。冲击氮掺杂样品对亚甲基蓝和罗丹明B染料有较好的吸附和可见光催化降解作用，其中高飞片速度处理的样品有更高的光催化降解活性。Abstract: Shock transformation and shock-induced chemical reaction in materials can lead to their obvious changes of physical and chemical properties. In this paper, the powder mixtures of nitrogen-rich of C2N4H4 and P25 TiO2 or metatitanic acid were shocked by the impact of flyer plates driven by explosive detonation, and the recovered samples were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis and UV-Vis spectra and evaluated by the photocatalytic degradation of methylene blue and Rhodamine B. The results indicate that the doping level of nitrogen-doped TiO2 reaches 8.88% (atom fraction) using the P25 TiO2 as raw materials which exhibits obvious absorption in visible region. Its energy gap decreases to 1.75 eV together with the formation of srilankite high-pressure phase. The doping level is 3%-4% (atom fraction) corresponding to the small variation of the energy gap using the metatitanic acid as raw materials. The specific surface area of the sample increases dramatically due to the unique shock dehydration-expansion mechanism. The nitrogen-doped TiO2 have better adsorption capability and photocatalytic activity under visible irradiation for the degradation of methylene blue and Rhodamine B, among which treated at higher impact velocity shows the higher photocatalytic activity.
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Key words:
- titania /
- shock synthesis /
- nitrogen doping /
- photocatalytic degradation
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