羧甲基纤维素复合石墨相氮化碳增强光催化合成过氧化氢的研究

Production of H_(2)O_(2) by Photocatalysis Enhanced by Graphitic Carbon Nitride Compositing with Carboxymethyl Cellulose

以三聚氰胺和三聚氰酸为双前驱体,通过水热、热缩合两步法合成石墨相氮化碳(g-C_(3)N_(4),CN),与羧甲基纤维素(CMC)通过多重氢键作用进行自组装结合,构建新型CN/CMC复合光催化材料。分别采用扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)、紫外可见漫反射光谱(UV-Vis DRS)和电子顺磁共振(EPR)等方法对CN/CMC复合光催化材料的微观形貌、晶体结构、化学组成、光电性质进行了测试分析,结果表明:CN中引入CMC后,CMC比较均匀地复合于CN表面,提高了复合材料的热稳定性,增加了其中C、N元素的电子密度,而未对CN的晶体及能带结构造成影响,但有助于氮化碳光生电子的快速迁移,在氙灯模拟太阳光(可见光)的照射下CN/CMC的光电流可达0.08μA/cm^(2),相比CN提升了约33%。对不同CMC用量复合材料的光催化性能的探讨中,当CMC用量为10%(以CN的质量计)时,可见光下,未添加任何牺牲剂时,CN/CMC的光催化合成H_(2)O_(2)的产量高达42μmol/(L·h),约是单纯CN的4倍。

Graphitic carbon nitride(g-C_(3)N_(4),CN)was prepared by a two-step hydrothermal and thermal polycondensation using melamine and cyanuric acid as dual precursors.Then,carboxymethyl cellulose(CMC)was self-assembled on CN via multiple hydrogen bonds to construct a novel CN/CMC composite photocatalyst.Scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),UV-Vis diffuse reflectance spectroscopy(UV-Vis DRS),and electron paramagnetic resonance(EPR)were applied to analyze the microstructure,crystal structure,chemical composition,and photoelectric properties of the catalysts.The results showed that after the introduction of CMC into CN,CMC was more uniformly compounded on the surface of CN,enhancing the thermal stability and the electron density of C and N elements in CN.However,it had not affected the crystal and energy band structure of CN,while contributing to the rapid migration of photogenerated electrons of carbon nitride.Under Xenon lamp-simulated solar light(visible light)irradiation,the photocurrent of CN/CMC could reach 0.08μA/cm^(2),which was approximately 33%higher than that of CN.In the investigation of the photocatalytic performance of composite materials with different amounts of CMC,when the amount of CMC was 10%(based on the mass of CN),the photocatalytic synthesis of H_(2)O_(2)by CN/CMC was 42μmol/(L·h)without adding any sacrificial agent under visible light,which was 4 times than that of CN alone.