基于煤炭及其衍生产物的荧光碳点制备与应用研究

发布时间：2018-06-12 22:45

本文选题：煤炭 + 煤沥青　；参考：《大连理工大学》2015年博士论文

【摘要】：以荧光碳点为代表的零维纳米材料是目前研究非常广泛的一类新型功能材料,其可控制备是当今纳米材料研究领域的前沿和热点之一。如何选用优质、廉价的碳源前驱体,并在制备过程中实现对荧光碳点结构和组成的准确控制,进而调变其本征性能,对于深入理解物质结构与性质的关联、人工设计合成新型功能材料具有重要意义。本文以煤炭及其衍生产物为碳源,针对不同原料的结构和性质,合理设计工艺路线,制备具有独特荧光性能的煤基碳点,主要研究结果如下：以煤炭为碳源前驱体,采用硝酸氧化法制备了具有蓝色荧光的煤基碳点,系统研究了碳源种类、煤岩结构、预炭化处理和氧化条件对煤基碳点收率、结构和性质的影响。结果表明高煤化度的煤炭和丝质组分有利于提高煤基碳点的量子产率,通过控制预炭化温度,可实现煤基碳点平均粒径从1.9nm到3.1nm范围内的精确调变。煤基碳点表面含氧官能团的种类和数量可通过后续还原处理来调控,经硼氢化钠还原后的煤基碳点的量子产率从1.02%大幅增大到8.80%。还原后的煤基碳点对铜离子具有特异性的荧光响应,可作为荧光探针用来监测水体中的铜离子,检测限可达2.0nM。以煤炭为碳源前驱体,采用电化学法制备了具有蓝色荧光的煤基碳点,考察了碳源种类,以及在电解液体系中引入含氮助剂对煤基碳点收率、结构和荧光性质的影响,并详细研究了煤基碳点在高浓度条件下的聚集状态和荧光变化规律。结果显示煤基碳点的收率远大于石墨基碳点,电解液中引入含氮助剂可实现氮掺杂煤基碳点的制备,煤基碳点在高浓度条件下荧光光谱红移。氮掺杂后的煤基碳点具有优异的催化性能,在电催化氧还原反应时表现出媲美商业Pt/C催化剂的催化活性,并且具有更好的稳定性和更强的抵御甲醇穿透效应的能力。以煤沥青为碳源前驱体,采用模板辅助法制备了具有蓝绿色荧光的煤沥青基碳点。碳点制备过程受到模板剂的纳米反应空间的限域效应影响,所得荧光碳点粒径非常均匀,平均尺寸为2.2nm。采用不同种类的有机修饰剂键连在沥青基碳点表面,不但极大地提高了碳点的量子产率,而且也改善了碳点与周围环境介质之间的相亲互溶性。乙二胺修饰后的碳点可均匀分散在有机玻璃固体介质中,即使在很高的浓度条件下也不易产生团聚,造成荧光猝灭。用这种碳点复合物作为光转化涂层,可成功将InGaN二极管的紫外光转变成蓝光。
[Abstract]:Zero-dimensional nanomaterials, represented by fluorescent carbon dots, are a new type of functional materials which are widely studied at present, and their controllable devices are one of the frontier and hot spots in the research field of nanomaterials. How to select the high quality and cheap carbon precursor, and how to control the structure and composition of the fluorescent carbon point accurately in the preparation process, and then adjust its intrinsic properties, which is helpful to understand the relationship between the structure and properties of the substance. It is of great significance to design and synthesize new functional materials. In this paper, coal and its derived products are used as carbon sources, according to the structure and properties of different raw materials, the technological route is designed rationally to prepare coal-based carbon points with unique fluorescence properties. The main results are as follows: coal is used as precursor of carbon source. Coal based carbon spots with blue fluorescence were prepared by nitric acid oxidation. The effects of carbon source types, coal rock structure, pre-carbonization treatment and oxidation conditions on the yield, structure and properties of coal based carbon points were systematically studied. The results show that the coal and silk components with high coalification degree can improve the quantum yield of coal-based carbon dots. By controlling the precarbonization temperature, the average particle size of coal-based carbon points can be accurately adjusted from 1.9nm to 3.1nm. The types and the number of oxygen-containing functional groups on the surface of coal-based carbon spots can be controlled by subsequent reduction treatment. The quantum yield of coal-based carbon dots reduced by sodium borohydride has been increased from 1.02% to 8.80%. The reduced coal-based carbon spots have a specific fluorescence response to copper ions and can be used as a fluorescence probe to monitor copper ions in water with a detection limit of up to 2.0 nm. Coal based carbon spots with blue fluorescence were prepared by electrochemical method using coal as carbon precursor. The effects of carbon sources and nitrogen-containing additives on the yield, structure and fluorescence properties of coal based carbon spots were investigated. The aggregation state and fluorescence variation of coal-based carbon point at high concentration were studied in detail. The results show that the yield of coal-based carbon point is much higher than that of graphite-based carbon point. The nitrogen-containing additive can be used to prepare the nitrogen-doped coal-based carbon point, and the fluorescence spectrum of coal-based carbon point can shift red under the condition of high concentration. The nitrogen-doped coal-based carbon spots have excellent catalytic performance and exhibit catalytic activity comparable to those of commercial Pt / C catalysts in the electrocatalytic oxygen reduction reaction. They also have better stability and stronger resistance to methanol penetration. Coal pitch based carbon spots with blue-green fluorescence were prepared by template assisted method using coal pitch as carbon precursor. The preparation process of carbon points is affected by the limiting effect of the nano-reaction space of the template. The size of the fluorescent carbon points is very uniform and the average size is 2.2 nm. Using different kinds of organic modifiers to bond on the surface of asphalten-based carbon points not only greatly improves the quantum yield of carbon dots, but also improves the compatibility and solubility between carbon points and surrounding media. The carbon points modified by ethylenediamine can be uniformly dispersed in the solid medium of plexiglass, and it is not easy to produce agglomeration even at very high concentration, which results in fluorescence quenching. The UV light of the InGaN diode can be converted into blue light successfully by using the carbon dot complex as the photoconversion coating.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ127.11;TQ536

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