碱木质素基碳量子点/TiO2复合光催化剂的制备

以碱木质素热解炭为碳源,采用酸回流法制备荧光水溶性纳米碳量子点,并通过扫描电子显微镜、透射电子显微镜、红外光谱和荧光分光光度法对其形貌、粒径分布、表面官能团以及荧光性质进行表征分析。结果表明:所制备的碳量子点粒径集中分布在1.5～2.5 nm之间,为均匀的类球状,且表面呈现有序的晶格结构; 红外光谱分析显示碳量子点表面存在―OH等大量的含氧官能团; 荧光光谱分析显示碳量子点在355 nm和442 nm处有特征激发和发射波长。当改变激发波长,发射波长产生红移,产物在可见光区域有较好的响应。在特定激发波长下随着pH的增大,碳量子点的光谱峰值呈现递减的趋势,当pH＞7,光谱发生蓝移现象。而且,制备出的碳量子点/TiO2复合光催化剂在可见光下表现出较好的降解性能,对苯酚的降解率达91%。
In this paper, we introduced the method of preparing carbon quantum dots(CQDs)by alkaline lignin pyrolytic carbon. The carbon quantum dots were prepared by acid reflux method. Carbon quantum dots/TiO2 composite photocatalyst were prepared by using blending method which combined carbon quantum dots and TiO2 together. Phenol was used as pollutant model for the visible light catalytic activity. Hydrosoluble carbon quantum dots were prepared by using acid reflux method from lignin pyrolytic carbon. SEM, TEM, FT-IR and fluorescence spectrophotometer were used to characterize the particle size distribution, structure and fluorescence properties. The results showed that the carbon quantum dots were uniform spheres in size with a diameter of 1.5-2.5 nm. FT-IR analysis showed that the surface of carbon quantum dots contained ―OH functional groups. Emission spectra around 400-600 nm with a peak at 442 nm were observed upon excitation at 355 nm. A peak centered at 355 nm in the excitation spectrum was present with an emission wavelength of 442 nm. Photoluminescence spectra also showed that the maximum emission and intensity had a direct relationship with the excitation wavelength. The fluorescence spectrum analysis showed that when the excitation wavelength was changed, the emission wavelength was red-shifted, and the product had a good response in the visible region. With the increase of pH at specific excitation wavelength, the peak of the carbon quantum dots showed a decreasing trend. When pH＞7, the spectrum of the spectrum was blue-shifted. The CQDs/TiO2 system was found to be an effective photocatalyst, and the CQDs on the surface of TiO2 acted as a photosensitizer. They had the wide spectral response range of TiO2 in the UV region, in addition to spectral response in the visible-light region. CQDs/TiO2 composite photocatalyst showed excellent catalytic activity with the phenol degradation percentage of 91%