铒掺杂g-C3N4催化剂的合成及其红光催化降解活性的研究

石墨相氮化碳(g-C₃N₄)的研究已成为光催化领域热点。本文以三聚氰氨为前驱体,采用甲醇回流法制备Er掺杂的g-C₃N₄催化剂。利用扫描电镜(SEM)、X射线光电子能谱(XPS)、X射线衍射仪(XRD)、紫外-可见-近红外分光光度计(UV-Vis-NIR DRS)、傅里叶红外光谱仪(IR)、荧光光谱(PL)、物理吸附(N₂-physisorption)及共聚焦显微镜(CLSM)等手段对Er/g-C₃N₄催化剂进行系统表征。结果表明,稀土金属Er高分散于g-C₃N₄上,促使氮化碳表面氮空穴的产生。Er掺杂优化了氮化碳的能带结构,增强了其对可见光的吸收,提升电子-空穴对的分离效率,此外还发现Er/g-C₃N₄具有较强的上转换能力。在660 nm红光LED照射下,对罗丹明B的水溶液进行光催化降解,发现Er/g-C₃N₄的降解速率是g-C₃N₄的2.0倍,且发现超氧自由基为该体系中的主要活性物种。

Synthesis of Erbium Doped g-C3N4 Catalyst and Its Photocatalytic Degradation Activity under Red Light

Graphite carbon nitride (g-C₃N₄) has become the hot research material in the field of photocatalysis. In this study, Er-doped g-C₃N₄ was synthesized by methanol-refluxing method using melamine as precursor. The resulting composite photocatalysts were characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), ultraviolet-visible-near infrared reflection spectrophotometer (UV-Vis-NIR Spectrophotometer), infrared spectrum (IR), photoluminescence spectroscopy (PL), N₂-physisorption and confocal laser scanning microscopy (CLMS). Results indicate that the rare-earth metal Er is highly disperse on g-C₃N₄ and it is favor for the introduction of nitrogen vacancies. The addition of Er optimize the energy band structure of g-C₃N₄, enhance the absorption of visible light, improve the electron-hole separation rate, furthermore, it is also found that Er/g-C₃N₄ photocatalyst process strong upconversion ability. The photocatalytic degradation of rhodamine B solution is performed under 660 nm LED red-light irradiation, and the rate constant of the Er/g-C₃N₄ is 2.0 times as high as that of pure g-C₃N₄. It is also found that the superoxide radical is the main active species for catalytic reaction in this system.