Synthesis, Characterization, and Nitrogen Concentration Depended Visible-Light Photoactivity of Nitrogen-Doped TiO2 Nanosheets with Dominant (001) Facets

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 °C 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.

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.

The visible-light photocatalytic activity of N doped TiO2 nanosheets depends on the (001) facets and N doped level which affects the photogenerated h+-e( recombination rate and ·OH generation ability.Figure optionsDownload as PowerPoint slide