氰基增强氮化碳光生载流子的有效分离

Cyano Groups Enhance the Effective Separation of Carbon Nitride Photogenerated Carriers

本文以碳酸锶(SrCO3)和三聚氰胺(C3H6N6)为原料,采用直接煅烧法制得了一系列m-SCCN复合光催化材料。研究了不同原料配比、不同煅烧温度以及不同煅烧时间制备的m-SCCN复合材料在可见光下对结晶紫溶液的光催化降解效果,并利用扫描电镜(SEM)、X射线粉末衍射仪(XRD)、紫外-可见吸收光谱(UV-Vis)等对该材料进行表征。结果表明,在SrCO3∶C3H6N6为7%(w/w),煅烧温度为600℃,煅烧时间为4 h时对结晶紫处理效果最佳。光照120 min后去除率可达到89.70%,是纯g-C3N4(17.70%)的5倍。分析机理可能是SrCO3破坏了g-C3N4平面内的部分氢键使得七嗪单元开环生成了强吸电子基团—氰基(-C≡N),从而改变了光生电子的传输途径,提高了光生电子和空穴的分离效率,优化了m-SCCN的光催化活性。

In this paper,a series of m-SCCN composite photocatalytic materials were prepared by direct calcination using strontium carbonate(SrCO3)and melamine(C3H6N6)as raw materials.The photocatalytic degradation effect of m-SCCN composites prepared by different raw material ratios,different calcination temperatures and different calcination time on crystal violet solution under visible light was studied.The materials were characterized by SEM,XRD,UV-Vis and so on.The results show that the treatment effect of crystal violet is best when SrCO3∶C3H6N6 is 7%(w/w),calcination temperature is 600℃,and calcination time is 4 h.The removal rate can reach 89.70%after 120 min of light,which is 5 times that of pure g-C3N4(17.70%).The analysis mechanism may be that SrCO3 destroys part of the hydrogen bonds in the g-C3N4 plane,resulting in the ring opening of the hepazine unit to generate a strong electron-withdrawing group-cyano group(-C≡N),which changs the transmission path of photogenerated electrons.The separation efficiency of photogenerated electrons and holes optimizes the photocatalytic activity of m-SCCN.