荧光碳点掺杂三氧化钨复合材料的制备、表征及光催化降解亚甲基蓝研究

发布时间：2018-07-07 23:18

本文选题：荧光碳点 + 三氧化钨　；参考：《辽宁大学》2017年硕士论文

【摘要】：随社会的快速发展,环境污染问题和能源危机越来越受到关注。作为一种可再生的清洁能源,如何利用太阳能光催化降解有机污染物已成为研究热点之一。三氧化钨可以用作光催化剂利用太阳能光催化降解水中的污染物,已成为一种解决污染问题的有效方法之一。但是,WO_3存在着可见光利用率较低问题。荧光碳点(CDs)除具有良好的光学性能外,还是良好的电子供体和受体,常用于改进一些光催化剂的光催化性能。本研究分别采用简单的溶剂热和微波法,先成功的制备出两种CDs,随后制备出CDs掺杂的WO_3复合材料(CDs-WO_3),并分别研究了复合光催化剂在可见光照射下的光催化性能。具体内容如下:1、以柠檬酸为碳源和甘氨酸为修饰剂,无水乙醇作为溶剂,采用溶剂热法一步合成发射黄色荧光的CDs。利用XRD、TEM、荧光光谱、紫外-可见吸收光谱和FT-IR光谱等技术对所得到的CDs的形貌、结构、光学性质和表面官能团等进行表征。并对反应温度、反应时间和甘氨酸的用量等实验条件进行了优化,研究了pH值和盐浓度对荧光强度的影响。研究结果表明:该方法合成的碳点属于无定形碳结构,颗粒大小约为10nm左右;碳点的荧光量产子率为26.0%,其表面含有大量的羟基和羧基等含氧官能团,增强了碳点的水溶性;用不同波长激发光照射,碳点表现出激发波长依赖性行为。此外还发现,所制备碳点还具有良好的耐光漂白和抗高盐能力。在溶剂热一步合成CDs的过程中,再加入WO_3,制备出CDs-WO_3复合材料,并研究其在可见光照射下对亚甲基蓝的光催化降解能力。使用XRD、SEM、EDS、Raman光谱、紫外-可见光漫反射光谱和红外光谱等技术对复合材料的形貌、结构和光学特性等进行了表征。此外,考察了光照时间、催化剂用量、pH值和制备过程中WO_3加入量等因素对CDs-WO_3的光催化降解活性影响。实验表明,在可见光照射下,片状的CDs掺杂的WO_3复合材料对亚甲基蓝具有良好的光催化降解性能。亚甲基蓝的初始浓度为10mg/L,复合材料用量为0.75g时,两小时内的光降解率达到60.0%。2、采用微波法,以酒石酸为碳源和甘氨酸为钝化剂,超纯水作为溶剂,一步合成发射绿色荧光的CDs。利用XRD、TEM、荧光分光光度计、紫外吸收光谱和FT-IR等技术对所得到的CDs的形貌、结构、光学性质和表面官能团进行了表征。研究中,对微波功率、加热时间、甘氨酸用量等实验条件进行了优化,并进一步讨论了pH值、无机盐浓度对CDs荧光发光强度的影响。研究结果表明:此方法制备的CDs具有无定形态的特征峰;其颗粒大小约为10nm;其表面含有大量的羟基和羧基等官能团,使水溶性增强;该CDs在不同激发光条件下,其发射峰发生Stokes shift位移,表现出波长依赖性行为;其量子产率为11.5%,并表现出良好的耐光漂白性;在较高盐浓度存在下,其荧光强度几乎不变,即具有较强的耐盐性。将制备好的CDs和WO_3放在水热反应釜内,在90℃下加热90min,制备出CDs-WO_3复合材料,并研究其在可见光照射下对亚甲基蓝的光催化降解能力。使用XRD、SEM、EDS、Raman、紫外-可见光漫反射光谱和红外光谱等技术对复合材料的形貌、结构、元素种类、光学特性和具有官能团进行表征。探究光照时间、催化剂用量、pH值和制备过程中WO_3加入量等因素对光催化降解活性的影响。实验表明:在可见光照射下,CDs-WO_3复合材料对亚甲基蓝具有良好的光催化降解性能。亚甲基蓝的初始浓度为10mg/L,加入6mLCDs溶液制备出的CDs-WO_3复合材料用量为25mg,两小时内的光降解率达到55.0%。3、本文用制备的两种CDs掺杂WO_3得到复合材料,光催化性能显著提高,表明掺杂CDs提高催化性能,成为可行的方法。
[Abstract]:With the rapid development of society, environmental pollution and energy crisis have attracted more and more attention. As a renewable clean energy, how to use solar energy to photocatalytic degradation of organic pollutants has become one of the hot spots. Tungsten trioxide can be used as a photocatalyst to degrade pollutants in water using solar energy, and it has become a solution. It is one of the effective methods to solve the problem of pollution. However, WO_3 has a low utilization rate of visible light. The fluorescent carbon point (CDs), in addition to good optical properties, is still a good electron donor and receptor. It is commonly used to improve the photocatalytic performance of some photocatalysts. This study was successfully prepared by a simple solvent heat and microwave method. Two kinds of CDs were produced and CDs doped WO_3 composites (CDs-WO_3) were prepared, and the photocatalytic properties of the composite photocatalyst under visible light were studied. The content of the photocatalyst was as follows: 1, using citric acid as carbon source and glycine as modifier and anhydrous ethanol as solvent, CDs. used XRD to synthesize CDs. using XRD for emitting yellow fluorescence. The morphology, structure, optical properties and surface functional groups of the obtained CDs were characterized by TEM, fluorescence spectra, UV visible absorption spectroscopy and FT-IR spectroscopy. The experimental conditions of the reaction temperature, reaction time and the dosage of glycine were optimized. The effects of pH and salt concentration on the fluorescence intensity were studied. The carbon dots synthesized by this method belong to the amorphous carbon structure, the size of the particles is about 10nm, the fluorescence yield of the carbon point is 26%, and the surface contains a large number of hydroxyl and carboxyl groups, which can enhance the water solubility of the carbon point. The carbon preparation points also have good photobleaching and high salt resistance. In the process of one step synthesis of CDs in solvent heat, the CDs-WO_3 composite is prepared by adding WO_3, and the photocatalytic degradation ability of methylene blue under visible light is studied. XRD, SEM, EDS, Raman spectroscopy, UV visible diffuse reflectance spectroscopy and infrared spectroscopy are used. The morphology, structure and optical properties of the composites were characterized. In addition, the effects of light time, amount of catalyst, pH value and WO_3 addition on the photocatalytic degradation activity of CDs-WO_3 were investigated. The experimental results showed that the WO_3 composites of WO_3 doped CDs were good for methylene blue under visible light irradiation. The initial concentration of methylene blue is 10mg/L, when the content of the composite is 0.75g, the photodegradation rate is 60.0%.2 within two hours. The microwave method is used to use the tartaric acid as the carbon source and the glycine as passivating agent and the ultra pure water as the solvent. The CDs. using XRD, TEM, fluorescence spectrophotometer and UV absorption is used in one step. The morphology, structure, optical properties and surface functional groups of the obtained CDs were characterized by spectral and FT-IR techniques. In the study, the microwave power, the heating time, the dosage of glycine and other experimental conditions were optimized, and the effect of the pH value and the concentration of inorganic salt on the fluorescence intensity of CDs was further discussed. The CDs has an amorphous characteristic peak, its particle size is about 10nm, and its surface contains a large number of hydroxyl and carboxyl groups and other functional groups, which can enhance the solubility of water. The emission peak of the CDs has a Stokes shift displacement and a wavelength dependent behavior under different stimulated luminescence conditions, and its quantum yield is 11.5%, and it shows good photobleaching resistance. In the presence of high salt concentration, the fluorescence intensity is almost constant, that is, it has strong salt tolerance. The prepared CDs and WO_3 are placed in a hydrothermal reactor, and the CDs-WO_3 composite is prepared by heating 90min at 90 C, and the photocatalytic degradation ability of methylene blue under visible light is studied. XRD, SEM, EDS, Raman, UV visible using XRD, SEM, Raman, and UV visible. The morphology, structure, element species, optical properties and functional groups of the composites were characterized by optical diffuse reflectance spectroscopy and infrared spectroscopy. The effects of light time, catalyst amount, pH value and WO_3 addition on the photocatalytic degradation activity were investigated. The experiment showed that the CDs-WO_3 composite was irradiated by visible light. The methylene blue has a good photocatalytic degradation performance. The initial concentration of methylene blue is 10mg/L, the amount of CDs-WO_3 composites prepared by adding 6mLCDs solution is 25mg and the photodegradation rate is 55.0%.3 within two hours. In this paper, two kinds of CDs doped WO_3 are used to get the composite, the photocatalytic performance is greatly improved, indicating that the doping CDs is improved. Catalytic performance is a feasible method.
【学位授予单位】：辽宁大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;O644.1

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