石墨相氮化碳纳米管的合成及光催化产氢性能

Graphitic Carbon Nitride Nanotubes:Synthesis and Photocatalytic Activity for Hydrogen Evolution

通过硬模板法,采用氰胺前驱物和二氧化硅纳米管(SiO2-NTs)模板,合成石墨相氮化碳纳米管(CN-NTs)光催化剂。采用扫描电镜(SEM)、透射电镜(TEM)、X射线粉末衍射(XRD)、傅立叶变换红外光谱(FT-IR)、氮气吸附/脱附测试、紫外可见漫反射光谱(UV-Vis DRS)、荧光光谱、热重分析(TGA)等手段对CN-NTs催化剂的结构与性能进行表征。结果表明,CN-NTs的化学组成是石墨相氮化碳(g-C3N4),形貌为均匀的纳米管,且是介孔材料。与体相氮化碳(B-CN)和介孔石墨相氮化碳(mpg-CN)相比,CN-NTs的光吸收带边蓝移到440nm,荧光发射谱的峰强减弱。在可见光(λ﹥420nm)照射下,CN-NTs具有较高的光催化分解水活性,产氢速率为58μmol/h,且表现出良好的光催化活性稳定性和化学结构稳定性。研究结果表明纳米管状结构能有效促进g-C3N4半导体激子解离,提高光生电子-空穴的分离效率,进而显著优化g-C3N4的光催化产氢性能。

Graphitic carbon nitride nanotubes（CN-NTs）photocatalyst has been synthesized by a hard-template method by using cyanamide as a precursor and silica nanotubes（SiO2-NTs）as a hard template.The structure and properties of CN-NTs catalyst are characterized by the techniques of scanning electron microscope（SEM）,transmission electron microscope（TEM）,X-ray powder diffraction（XRD）,Fourier transform infrared spectroscopy（FT-IR）,nitrogen absorption/desorption experiment,ultraviolet visible diffuse reflectance spectroscopy（UV-Vis DRS）,fluorescence spectra and thermogravimetric analysis（TGA）.As demonstrated by the experimental results,CN-NTs possess the chemical structure of graphitic carbon nitride（g-C3N4）and the morphology of uniform nanotubes,and belong to mesoporous materials.Compared with the bulk carbon nitride（B-CN）and the mesoporous graphitic carbon nitride（mpg-CN）,the optical absorption band edge of CN-NTs blue-shifts to 440 nm,and the peak intensity of the fluorescence emission spectra for CN-NTs reduces.With the visible light irradiation（λ420nm）,CN-NTs show an outstanding photocatalytic water splitting activity with the hydrogen evolution rate of 58μmol/h,and also demonstrate excellent stability in photocatalytic activity and chemical structure.The investigation results indicate that the nanotube structure effectively promotes the exciton separation of g-C3N4 semiconductor,and improves the separation efficiency of photogenerated electrons and holes,thus remarkably optimizing the photocatalytic activity of g-C3N4 toward hydrogen evolution.