煤基石墨烯的制备、修饰及应用研究

发布时间：2018-06-11 22:23

本文选题：煤 + 石墨烯　；参考：《西安科技大学》2015年博士论文

【摘要】：石墨烯作为一种新型二维碳材料,具有独特的结构特征和优异的电学、力学、光学以及热学性质,在储能、催化、传感器等领域有着良好的应用前景,引起了世界的广泛关注。廉价、可控制备石墨烯以及石墨烯材料的功能化修饰是影响石墨烯材料发展和应用的关键。煤炭是自然界富存的以多环芳烃结构单元为主的含碳有机物,在新型碳材料制备中扮演着重要角色。本论文以煤炭为原料,针对煤基石墨烯的可控制备及其在光催化和电化学领域的应用进行了研究。在石墨烯制备方面重点研究了煤结构对煤石墨化过程的影响,探讨了影响煤基石墨烯结构和性能的主要因素;在应用方面重点考察了煤基氧化石墨烯复合材料在CO_2光催化过程中的催化特性以及煤基石墨烯复合材料的电化学性能。相关研究结果对于开拓煤炭材料化利用的新途径,阐明影响煤基石墨烯结构和性能的因素具有重要的理论和应用价值。首先,在煤基石墨烯制备方面,论文探讨了煤基石墨和煤基石墨烯制备的方法,以及影响石墨烯光催化特性和电化学性能的关键因素。煤经过不同石墨化工艺进行结构调变之后,进一步采用氧化法和低温等离子体还原技术实现了煤基石墨烯的制备。研究结果表明:在2500℃及1500℃条件下,催化石墨化均可以实现煤有机大分子结构的有序化调变,所得煤基石墨的石墨化度均可达到65%以上;当煤中加入氯化铁/硼酸复合催化剂,经过1500℃热处理后,所得煤基石墨的石墨化度可以提高到71.63%。此外,不同变质程度的煤经催化石墨化作用后,其产物的石墨化程度也有差异,无烟煤因其有机大分子基本结构单元中芳香层片更大,因此更易石墨化。催化石墨化机理表现为硼元素削弱煤炭有机大分子结构中芳香层片之间桥键的交联作用,铁元素与分解得到的芳香层片相结合形成相应的碳化物,当催化剂中无序排列的炭达到饱和时,部分炭以低能级的石墨化碳结晶形态沉积下来形成煤基石墨。其次,研究了ZnO/煤基氧化石墨烯复合材料在CO_2光催化还原过程中的应用。本研究以煤基氧化石墨烯为基材,通过共沉淀法制备了ZnO/煤基氧化石墨烯复合材料,考察了煤基氧化石墨的结构及ZnO负载量对复合材料光催化CO_2还原过程的影响。研究结果表明:不同负载量的ZnO/煤基氧化石墨烯复合材料对CO_2的光催化还原均具有一定光催化作用,其在可见光区的催化活性和选择性明显优于紫外光区,煤基氧化石墨烯结构及特性是影响ZnO/煤基氧化石墨烯复合材料光催化活性和选择性的关键因素;在可见光作用下,ZnO/煤基氧化石墨烯复合材料的光催化活性表现为ZnO/KCGO复合材料ZnO/TXGO复合材料ZnO/JCGO复合材料(复合比为7:3,添加量为1g/L),并且对甲酸有较高的选择性,产物中甲酸产率与甲醇产率之比最高可达35.36。这主要是由于煤基氧化石墨烯的加入,其自身较大的间隙能,增强了该复合材料在可见光区的吸收能力,同时有助于促进光生电子的还原能力。最后,本论文研究了煤基石墨烯及MnO_2/煤基石墨烯复合材料在超级电容器电极材料中的应用,分析了煤基石墨烯片层大小和结构缺陷对煤基石墨烯及其复合材料电化学性能的影响。当煤基石墨烯材料用作超级电容器正极材料时,其首次充放电比电容量的高低顺序为:KCGTXGJCG;当MnO_2/煤基石墨烯复合材料用作超级电容器正极材料时,首次充放电的比电容量值相较于煤基石墨烯有了很大提高,这是因为石墨烯片层结构与线性二氧化锰复合时产生了强烈的协同效应,使复合材料展现出优异的导电性能;煤基石墨烯的结构不同,其与二氧化锰协同效应的大小也有差异,其中,MnO_2/TXG复合材料的电化学性能提高最明显,首次充放电的比电容量可以达到159.05 F/g,是TXG比电容量的3倍多。这主要归因于TXG具有更大的石墨烯层片结构,使二氧化锰纳米棒更易均匀分散在煤基石墨烯层片间,从而形成通畅的电子传输通道,提高了复合材料导电性能。
[Abstract]:Graphene, as a new type of new two-dimensional carbon material, has unique structural characteristics and excellent electrical, mechanical, optical and thermal properties. It has a good application prospect in the fields of energy storage, catalysis, sensor and so on. It has aroused wide attention in the world. The key to the development and application of alkene materials. Coal is a carbon containing organic substance, which is rich in the structure unit of polycyclic aromatic hydrocarbons in nature. It plays an important role in the preparation of new carbon materials. In this paper, the controllable preparation of coal and its application in the field of photocatalysis and electrochemistry are studied with coal as the raw material. In Shi Moxi, the paper has been studied in this paper. The effect of coal structure on the process of coal graphitization is studied, and the main factors affecting the structure and properties of the coal cornerstone are discussed. In the application, the catalytic properties of the coal based graphene oxide composite in the CO_2 photocatalytic process and the electrochemical performance of the coal based graphene composite are investigated. It has important theoretical and application value for developing new ways of coal material utilization and clarifying the factors affecting the structure and properties of coal cornerstone's graphene. First, the preparation of coal based graphite and coal based graphene, as well as the key to the photocatalytic and electrochemical properties of the cornerstone are discussed in the preparation of the cornerstone alkene. Factors. After structural modification of coal through different graphitization processes, the preparation of coal cornerstone methenes is further prepared by oxidation and low temperature plasma reduction technology. The results show that under the conditions of 2500 and 1500 C, catalytic graphitization can realize the orderly modulation of coal organic large sub structure and the obtained coal based graphite stone. The graphitization degree of the coal based graphite can be increased to 71.63%. after the addition of iron chloride / boric acid composite catalyst and heat treatment at 1500 C. The degree of graphitization of the products with different metamorphic degrees is also different after the catalytic graphitization, and the anthracite coal is based on the organic macromolecules. The mechanism of the catalytic graphitization is that boron elements weaken the crosslinking of the bridge bonds between the aromatic layers in the organic large molecular structure of coal, and the iron elements are combined with the decomposed aromatic layers to form the corresponding carbides. When the disordered charcoal is saturated, some carbon is obtained. Coal based graphite was deposited at low energy crystalline carbon crystalline form. Secondly, the application of ZnO/ coal based graphene oxide composite in the process of CO_2 photocatalytic reduction was studied. The ZnO/ coal based graphite oxide composite was prepared by co precipitation method. The coal based graphite oxide composite was prepared by co precipitation method. The coal based graphite oxide graphite was investigated. The effect of the structure and ZnO load on the photocatalytic CO_2 reduction process of the composite material. The results show that the ZnO/ coal based graphite oxide composite with different loads has a certain photocatalytic effect on the photocatalytic reduction of CO_2, and its catalytic activity and selectivity in the visible region are obviously superior to the UV light zone, and the coal based graphite oxide fines The structure and characteristics are the key factors affecting the photocatalytic activity and selectivity of the ZnO/ based graphite oxide composite. The photocatalytic activity of the ZnO/ coal based graphene oxide composite material under the visible light is ZnO/KCGO composite material ZnO/TXGO composite material ZnO/JCGO composite (composite ratio 7:3, adding amount 1g/L) and formic acid With high selectivity, the ratio of formic acid yield to methanol yield is up to 35.36., which is mainly due to the addition of coal based graphene oxide, its own larger gap energy, enhanced absorptive capacity of the composite in visible light area, and help to promote the reduction of photoelectron. Finally, this paper has studied the cornerstone of coal. The application of alkene and MnO_2/ cornerstone composite material in supercapacitor electrode materials, the influence of the size and structural defects of the cornerstone lamellar layer on the electrochemical performance of the coal cornerstone and its composites was analyzed. When the coal cornerstone material was used as the cathode material for the supercapacitor, the initial charge discharge specific capacity of the material was high and low. The order is: KCGTXGJCG; when the MnO_2/ cornerstone lamene composite is used as a supercapacitor cathode material, the specific capacity of the first charge and discharge is greatly improved than that of the cornerstone ink. This is due to the strong synergistic effect of the composition of the graphene lamellar structure with the linear manganese dioxide, which makes the composite exhibit excellent guidance. Electrical properties, the structure of the coal based alkene is different, and the size of the synergistic effect of manganese dioxide is also different. Among them, the electrochemical performance of MnO_2/TXG composites is increased most obviously. The specific capacity of the first charge discharge can reach 159.05 F/g, which is more than 3 times more than the capacitance of TXG. This is mainly due to the larger graphene layer structure of TXG. MnO2 nanorods are more easily dispersed among the coal base graphene lamellae, thus forming a smooth electron transport channel and improving the electrical conductivity of the composites.
【学位授予单位】：西安科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ127.11

【相似文献】