氮缺陷石墨相氮化碳的制备及其光催化降解环境有机污染物性能

通过在三聚氰胺热分解过程中加入NaHCO₃制备出具有氮缺陷的石墨相氮化碳（g-C₃N₄），利用X射线衍射（XRD）、傅里叶变换红外光谱（FT-IR）、N₂吸附-脱附、X射线光电子能谱（XPS）、紫外-可见漫反射光谱（UV-vis DRS）和固体荧光光谱（PL）等方法对其进行表征，并在可见光（λ> 420nm）照射下，以水相中罗丹明B（RhB）的降解为模型反应，研究了该氮缺陷g-C₃N₄对有机污染物降解的光催化活性。结果表明，引入氮缺陷可以提高g-C₃N₄对可见光的吸收以及电子-空穴对的分离效率，进而提高g-C₃N₄的可见光催化活性。催化剂CNK0.005、CNK0.01和CNK0.05在30min内对RhB的降解率分别为79.8%、100.0%和87.6%；而在相同条件下，没有氮缺陷的g-C₃N₄对RhB的降解率仅为59.8%。

Preparation of graphitic carbon nitride with nitrogen-defects and its photocatalytic performance in the degradation of organic pollutants under visible light

Various graphitic carbon nitride (g-C₃N₄) materials having nitrogen defects were synthesized by adding NaHCO₃ during the thermal polymerization of melamine. The as-prepared g-C₃N₄ samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), nitrogen adsorption-desorption, X-ray photoelectron spectroscopy (XPS), UV-visual diffuse reflectance spectroscopy (UV-vis DRS) and photoluminescence spectroscopy (PL); their photocatalytic activity in the degradation of Rhodamine B (RhB) under visible light irradiation was investigated. The results demonstrated that the unique nitrogen defects in g-C₃N₄ play an important role in broadening the absorption of visible light and enhancing the separation of electron-hole pairs. The photocatalytic activity of g-C₃N₄ with nitrogen defects is enhanced greatly; the RhB removal rates over the CNK0.005, CNK0.01, and CNK0.05 photocatalysts in 30 min reach 79.8%, 100.0% and 87.6%, respectively. In contrast, the pristine g-C₃N₄ free of nitrogen defects only gives an RhB degradation rate of 59.8% under the same reaction conditions.