碳量子点修饰石墨相氮化碳光催化降解罗丹明B的研究

Photocatalytic degradation of rhodamine B by carbon quantum dot modified graphite phase carbon nitride

利用抗坏血酸(AA)对石墨相氮化碳(g-C3N4)进行改性,制备出表面含有碳量子点(CQDs)的催化剂CQDs/g-C3N4.通过X射线衍射(XRD)、紫外可见光漫反射(UV-Vis DRS)、透射电镜(TEM)、光致发光光谱(PL)、X射线光电子能谱(XPS)对催化剂进行结构、形貌、光学性能测试.发现CQDs很好的负载到了g-C3N4表面,增加了催化剂表面活性位点.UV-Vis DRS表明碳量子点能够使催化剂的吸收光谱发生红移,同时缩小了催化剂的带隙宽度,增强了对光的吸收能力.光致发光光谱则显示了碳量子点的修饰能够有效的抑制光生电子空穴对的复合,从而提高光催化性能.通过光降解实验表明0.01g CQDs/g-C3N4催化剂在80℃下,3h对罗丹明B(RhB)的降解率为57.2%.捕获剂实验则说明了超氧自由基(·O2^-)在光降解体系中起到了促进反应速率的作用.

In this study,CQDs/g-C3N4 was prepared by using ascorbic acid and urea as precursors.The characterizations of CQDs/g-C3N4 were carried out by X-ray diffraction(XRD),ultraviolet visible light diffuse reflection(UV-vis),transmission electron microscopy(TEM),fluorescence spectrum(PL),X-ray photoelectron spectroscopy(XPS).The results showed that carbon quantum dots were well loaded onto the surface of graphite phase carbon nitride bringring about the active sites of g-C3N4 increase.The CQDs modification could effectively improve the visible light absorbance of g-C3N4,as well as decrease its band gap.At the same time,the addition of carbon quantum dots could inhibit the recombination of photogenerated electron-hole pair in catalyst.Under simulated light irradiation,the RhB photodegradation ability of CQDs/g-C3N4 was significantly higher than that of single g-C3N4.56.7% of RhB could be degraded over 0.01g of CQDs/g-C3N4 at 80℃ in 3h.Capture agent experiment result showed that superoxide radical played a major role in the photodegradation reaction system.