蓝、绿两种荧光碳点的合成、表征及其光催化降解性能研究

发布时间：2018-04-25 17:20

本文选题：荧光碳点 + 制备　；参考：《辽宁大学》2015年硕士论文

【摘要】：目前,有关荧光碳点(C-dots)制备和应用研究受到越来越多科学人员的关注。主要原因是:1)分子量、粒径尺寸都很小,毒性也较低,具有较强的穿透能力,易于实现细胞内标记和成像。2)荧光性能稳定,经过紫外灯多次激发数小时,其光致发光强度几乎不变。3)在光源激发下是优良的电子供体和受体,表现出光诱导电子转移的性质。本研究采用简单方便的一步水热法,成功地制备出发蓝、绿两种颜色的荧光碳点,同时又分别探究了它们在光催化降解有机染料方面的特性,为光催化剂的设计与催化机理研究提供了新的选择和思路。主要研究内容、结果和结论如下:1、以葡萄糖为碳源和L-半胱氨酸作为修饰剂,采用水热法一步合成出发射蓝色荧光的C-dots。利用XRD、TEM、荧光光谱、紫外吸收光谱和红外光谱等技术对所得到的C-dots的形貌结构、光学性质和表面基团等进行了表征。研究中,优化了反应时间、反应温度和L-半胱氨酸用量等实验条件,并探讨了p H值、钠离子、Cu2+对C-dots的光致发光性能影响。结果表明:该方法合成的C-dots含有碳的无定形态结构的特征峰;其粒径在12.5nm左右;羟基和羧基等含氧基团被引入到C-dots表面,增强了其水溶性;该纳米粒子表现出激发波长依赖的发光性能,其量子产率为5.2%;另外其有较好的光稳定性。在较高浓度的Na Cl存在下,其荧光强度变动不大,即具有较强的耐盐性,但在一定的Cu2+共存下,C-dots的荧光强度明显降低。以C-dots作为光催化剂,研究其在模拟可见光照下对甲基绿的光催化降解性能。考察了光照时间、甲基绿初始浓度、催化剂用量等因素对光催化降解的影响。实验表明:在过氧化氢存在下,C-dots对甲基绿具有良好的光催化降解性能。当甲基绿初始浓度为40mg/L,碳纳米粒子用量为2ml时,3小时内甲基绿的降解率达到90%以上。2、采用溶剂热法,以抗坏血酸和甘氨酸为碳源,在无水乙醇和磷酸介质中,一步合成发射绿色荧光的C-dots。利用XRD、TEM、荧光光谱、紫外吸收光谱和红外光谱技术等对所得到的C-dots的形貌结构、光学性质和表面基团等进行了表征。研究中,对反应温度、实验时间、甘氨酸用量等实验条件进行了优化,并探讨了p H值、无机盐离子、Cu2+对C-dots光致发光性能的影响。结果表明:该方法所制备的C-dots具有碳的无定形态的特征峰;其粒径在9.8nm左右;含氧的羟基和羧基等被引入到C-dots表面,增强了其水溶性;该纳米粒子也表现出在不同激发光条件下,其发射峰位不变,荧光强度有所改变的性质,其量子产率为8.3%,并表现较好的光稳定性;在较高浓度的Na Cl存在下,其荧光强度变化不大,即具有较强的耐盐性,但在一定的Cu2+共存下,其荧光强度明显降低。以C-dots作为光催化剂,研究其在模拟太阳光照下对酸性品红的光催化降解性能。实验探讨了光照、降解物初始浓度、催化剂用量等因素对光催化降解酸性品红的影响。实验结果表明:在过氧化氢存在下,C-dots对酸性品红具有良好的光催化降解性能。对于初始浓度为20mg/L的酸性品红溶液,1小时内的降解率可达98%以上。
[Abstract]:At present, more and more scientists have attracted more and more attention on the preparation and application of fluorescent carbon dots (C-dots). The main reasons are: 1) molecular weight, small size of particle size, low toxicity, strong penetration ability, easy realization of intracellular labeling and imaging.2) with stable fluorescence performance, photoluminescence after several hours of ultraviolet lamp excitation. Under the excitation of light source, it is an excellent electron donor and receptor, showing the properties of light induced electron transfer. In this study, a simple and convenient one step hydrothermal method was used to successfully prepare two colors of blue and green fluorescent carbon points. At the same time, the characteristics of their photocatalytic degradation of organic dyes were investigated. The main research content, results and conclusions are as follows: 1, using glucose as the carbon source and L- cysteine as a modifier, the blue fluorescent C-dots. is synthesized by hydrothermal method, and the technology of XRD, TEM, fluorescein, UV absorption and infrared spectroscopy is used. The morphology, optical properties and surface groups of the C-dots were characterized. In the study, the reaction time, reaction temperature and L- cysteine dosage were optimized, and the effects of P H value, sodium ion and Cu2+ on the photoluminescence properties of C-dots were investigated. The results showed that the synthesized C-dots contains amorphous form of carbon. The particle size of the structure is about 12.5nm, and the hydroxyl and carboxyl groups are introduced to the surface of C-dots to enhance their water solubility; the nanoparticles exhibit a luminescent property of excitation wavelength dependence, with a quantum yield of 5.2%, and a better light stability. The fluorescence intensity changes little in the presence of a high concentration of Na Cl, that is, It has strong salt tolerance, but under certain Cu2+ coexistence, the fluorescence intensity of C-dots is obviously reduced. The photocatalytic degradation performance of methyl green under the simulated visible light is studied with C-dots as a photocatalyst. The effects of light time, initial concentration of methyl green and the amount of catalyst on the photocatalytic degradation are investigated. In the presence of hydrogen peroxide, C-dots has a good photocatalytic degradation performance for methyl green. When the initial concentration of methyl green is 40mg/L and the amount of carbon nanoparticles is 2ml, the degradation rate of methyl green within 3 hours is over 90%.2, and a solvent thermal method is used to synthesize ascorbic acid and glycine as carbon source and one step is synthesized in anhydrous ethanol and phosphoric acid medium. The green fluorescence C-dots. uses XRD, TEM, fluorescence spectrum, UV absorption spectrum and infrared spectroscopy to characterize the morphology, optical properties and surface groups of the obtained C-dots. In the study, the reaction temperature, the time of experiment, the dosage of glycine and so on were optimized, and the P H value, the inorganic salt ion, and the Cu2+ were discussed. The effect on the photoluminescence properties of C-dots shows that the C-dots prepared by this method has the characteristic peak of amorphous carbon, and its particle size is about 9.8nm, and the hydroxyl and carboxyl group containing oxygen are introduced to the surface of C-dots, and the water solubility is enhanced, and the nanoparticles also show that the emission peak is constant and the fluorescence intensity is strong under the unexcited luminescence condition. The quantum yield is 8.3%, and the light stability is better. In the presence of high concentration of Na Cl, the fluorescence intensity changes little, that is, it has strong salt tolerance, but the fluorescence intensity is obviously reduced under the coexistence of a certain Cu2+. C-dots is used as a photocatalyst to study the acid products under the simulated sunlight. The effects of light, initial concentration of degrading substances and amount of catalyst on the degradation of acid fuchsin were investigated. The experimental results showed that C-dots had good photocatalytic degradation performance for acid fuchsin in the presence of hydrogen peroxide. For 1 hours, an acid fuchsin solution with initial concentration of 20mg/L was in the presence of hydrogen peroxide. The degradation rate can reach more than 98%.

【学位授予单位】：辽宁大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ422;TQ127.11

【参考文献】