N掺杂富含(001)晶面TiO2纳米片的制备及N掺杂浓度对可见光催化活性的影响

摘要

采用水热法制备了富含(001)晶面的锐钛矿型TiO2纳米片,并通过改变热处理过程中NH3流速制备不同N掺杂浓度的TiO2纳米片.运用X射线衍射、场发射扫描电镜、高分辨率透射电子显微镜、紫外-可见漫反射光谱、X射线光电子能谱和荧光光谱对光催化剂进行了结构和性能表征,并以罗丹明B为目标降解物,考察了N掺杂浓度对TiO2纳米片可见光催化活性的影响.结果表明,NH3流速为40 ml/min时制备的N掺杂TiO2纳米片具有最低的光生电子-空穴复合速率,最高的·OH产生能力并表现出最高的光催化活性.同时,讨论了N掺杂浓度对TiO2纳米片可见光催化活性影响的机理.%Anatase TiO2 nanosheets with dominant (001) facets were prepared by a simple hydrothermal method.Nitrogen-doped TiO2 nanosheets (TiO2-N) with different nitrogen concentration were successfully synthesized by annealing TiO2 nanosheets in NH3 atmosphere with different NH3 flow rate at 400 ℃ for 3 h.The morphology,nanostructures,and properties of TiO2-N were characterized by X-ray diffraction,field emission scanning electron microscopy,high resolution transmission electron microscopy,ultraviolet-visible diffuse reflection spectroscopy,X-ray photoelectron spectroscopy,and photoluminescence.The effects of NH3 flow rate on the nanostructures,properties,and visible-light photoactivity in the degradation of rhodamine B (RhB) aqueous solution under visible light (λ ＞ 400 nm) irradiation of the prepared photocatalysts were investigated.Among all the prepared photocatalysts including nitrogen modified P25 (Degussa),TiO2-N prepared with a NH3 flow rate of 40 ml/min gave the highest visible-light photoactivity because of the dominant (001) facets,visible light responsibility,the slowest photogenerated electron (e-) and hole (h+) pairs recombination rate,and the highest hydroxyl radicle (·OH) generation ability.Based on these experiments and analysis,the mechanisms of how the nitrogen concentration affects the visible-light photoactivity of TiO2-N were proposed.