碳量子点/g-C3N4复合光催化剂的制备及光催化降解四环素性能

Synthesis of carbon quantum dots/g-C3N4 and its photocatalytic degradation properties of tetracycline

通过一步煅烧法制备了碳量子点修饰氮化碳(CQDs/g-C3N4)复合光催化剂,采用TEM、XPS、UV-vis、FT-IR、稳态荧光光谱(PL)及电化学阻抗等对催化剂进行了表征,考察了可见光下催化剂对水中四环素(TC)的光降解活性.结果表明,少量CQDs的沉积不仅增加了g-C3N4的活性位点,而且加快了g-C3N4表面电荷的转移,抑制了载流子的复合,进而提升了其光催化降解活性.在优化条件下,1 mL CQDs溶液(1 g/L)修饰的g-C3N4(1CCN)对TC的光催化降解效率为纯相g-C3N4的1.5倍;通过探究其活性增强原因发现,光催化活性的提升主要归因于CQDs在复合体系中的沉积,及其可作为电子储存器加快g-C3N4光激发所产生的电子转移,有效地抑制电子-空穴对的重组.

A carbon quantum dot modified carbon nitride(CQDs/g-C3N4)composite photocatalyst was synthesized via a one-step calcination method for degradation of tetracycline(TC)under visible-light irradiation.A series of characterizations by means of TEM,XPS,UV-vis,FT-IR,PL,electrochemical means and so on,were carried to analysis the as-prepared samples.The results show that the load of a small amount of CQDs not only enriches the active sites of g-C3N4,but also accelerates the transfer of g-C3N4 surface charge and inhibits the recombination of carriers,enhancing its photocatalytic degradation activity.The photocatalytic degradation efficiency of g-C3N4 modified with 1mL CQDs solution(1g/L)(1CCN)to TC is 1.5 times that of the pristine g-C3N4.Meanwhile,the reasons for its enhanced activity are explored.The results reveal that the increased photocatalytic activity is mainly attributed to the two effects of CQDs in the composite system:the load of CQDs which greatly enhances the absorption of visible-light by g-C3N4,and CQDs can be used as the electron reservoirs to accelerate the transfer of electrons generated by g-C3N4 photoexcitation,effectively suppressing the recombination of electron-hole pairs.