纳米石墨相氮化碳的可控制备及在储能和光催化领域的应用

发布时间：2018-07-04 19:01

本文选题：氮化碳管状 + 纤维微串　；参考：《北京理工大学》2015年博士论文

【摘要】：石墨相氮化碳(CCN)具有优越的机械性能、独特的电子结构和优异的化学稳定性,近年来不仅被作为有机合成反应的催化剂,还被应用于开光电转换器、气敏传感器和荧光传感器、场发射器、燃料电池电极和储氢材料等领域,是一种极有前途的材料。本文研究石墨相氮化碳的制备、表征、生长机理及其性能.本文使用新的化学方法合成该材料,通过场发射扫描电子显微镜(FESEM)、X射线衍射(XRD)、光电子能谱(XPS)、X光能谱散布分析仪(EDX)、透射电子显微镜(TEM)、高分辨率透射电子显微镜(HRTEM)及选区电子衍射(SAED)等测试手段对获得的新形貌的GCN样品进行表征,这种材料潜在的性能包括光催化剂、超级电容器、氧还原,析氧和析氢反应等。首先,使用一种简单、高效、绿色环保的化学方法,将三聚氰胺粉末放在浓硝酸中低温下预处理,合成了具有高比表面积、微串状独特形貌的石墨相C3N4(ms-GCN)材料。ms-GCN在可见光下可以催化降解罗丹明B、甲基蓝和甲基橙。由于高比表面积和合适的禁带宽度,表现出较高的光降解效率。ms-GCN的一级降解速率常数高于已报道的其它材料,例如GCN, Fe2O3/GCN and TiO2纳米管。因此,这种合成方法可以获得高的表面积和独特的形态,使材料具有更高光降解活性。其次,我们建立了一种简单的可规模化的制备管状石墨相C3N4 (TGCN)的方法。独特的管状形貌的构建是基于用浓硝酸预处理三聚氰胺。本文首次将管状TGCN作为超级电容器的电极材料并测试其电化学储能性能,在6摩尔的氢氧化钾溶液、0.2A/g电流密度下的电容为233 F/g,优良的性能归功于高表面积(182.61 m2/g)和氮元素的存在。另外,1000次循环后电容保持率仍然高达90%。,在可见光下测试了TGCN光催化降解有机染料亚甲蓝(MB)和亚甲基橙(MO)的性能,相比于体相GCN, TGCN显示出良好的光催化活性和稳定性。TGCN材料的高催化活性来源于高表面积可以提供更多的活性位点。TGCN在超级电容器和光催化方面的良好性能使其成为能源存储和清洁环境领域充满前景的材料。然后,我们开发出一种简单、高效、可规模化的方法制备GCN纳米线作为超级电容器电极材料和光催化剂。制备的一维结构GCNNF1内米线优点如下：1、氮含量更高,有利于提高导电性和电化学性能；2、具有高表面积可以提供更大的电极-电解液接触面积、促进可见光吸收和物质传输,进一步的增加氧化还原电位。因此,GCNNF作为超级电容器电极材料在0.1摩尔Na2SO4电解质、1 A/g电流密度下的电容为263.75 F/g,2000循环后电容保留率仍然高达93.6%,即使在高电流密度(10 A/g)下电容也能达到208 F/g,其电容保持率仍然高达89.5%。此外,与体相石墨型C3N4(GCN)相比,GCNNF在降解RhB时表现出更高的光催化活性,降解速率常数高于体相石墨型C3N4(GCN)光催化剂的4倍,这主要归功于GCNNF拥有更高的表面积,合适的能带和更少的缺陷。作为价格低廉的前驱体,三聚氰胺合成GCNNF的方法无害简易且无需使用模板剂,得到的产品GCNNF在超级电容器和光催化降解方面表现出优良的性能,有望应用于能源存储和环境保护应用领域。之后,本文使用拥有类此结构的TGCN和GCNNF材料以探索石墨相氮化碳(GCN)的形貌对催化性能的影响,研究两种形貌的氮化碳在在碱性电解质中氧还原反应(ORR)的活性。其中管状GCN材料在溶解氧中氧还原反应(ORR)的起始电势接近商用Pt/C材料。此外,相比与Pt/C,管状的GCN表现出比Pt/C更高的稳定性和甲醇耐受性,适合燃料电池的应用。最后,本文发展出一种简易、可大规模生产的低温化学方法制备C0304修饰的的石墨相氮化碳(GCN)纳米管。管状石墨相氮化碳(GCN)和C0304之间强烈的协同效应使其可以作为析氧(OER)和析氢(HER)反应的双功能催化剂。高表面积、独特的结构和复合组分使C03O4@GCN拥有更加容易接触的的氧化还原催化位点。对于OER反应,相较于基准物IrO2和RuO2,Co3O4@GCN纳米复合材料在碱性电解质中展现出更高的超电势(0.12 V)和电流密度(147 mA/cm2)以及更好的耐久性。此外,Co3O4@GCN纳米复合材料在HER反应中也表现出更低的过电势和稳定的电流密度等优异性能。预计Co3O4@GCN纳米复合材料在大规模光解水和燃料电池领域具有比贵金属更大的吸引力。
[Abstract]:Graphite phase carbon nitride (CCN) has excellent mechanical properties, unique electronic structure and excellent chemical stability. In recent years, it has been used not only as a catalyst for organic synthesis, but also in the fields of optoelectronic converters, gas sensors and fluorescence sensors, field launchers, fuel cell electrodes and hydrogen storage materials. In this paper, we study the preparation, characterization, growth mechanism and properties of graphite phase nitriding. This paper uses a new chemical method to synthesize the material by field emission scanning electron microscopy (FESEM), X ray diffraction (XRD), photoelectron spectroscopy (XPS), X light spectrum dispersive analyzer (EDX), transmission electron microscope (TEM), high resolution transmission electron Microscopically (HRTEM) and elective electron diffraction (SAED) are used to characterize the newly formed GCN samples. The potential properties of this material include photocatalyst, supercapacitor, oxygen reduction, oxygen evolution and hydrogen evolution reaction. First, a simple, efficient, green chemical method is used to put melamine powder in concentrated nitric acid. The graphite phase C3N4 (ms-GCN) material.Ms-GCN with high specific surface area and unique morphology is synthesized under low and medium temperature, which can catalyze the degradation of Luo Danming B, methyl blue and methyl orange under visible light. The first order degradation rate constant of.Ms-GCN is higher than that with high surface area and proper band gap, which shows higher photodegradation efficiency.Ms-GCN. Other materials reported, such as GCN, Fe2O3/GCN and TiO2 nanotubes. Therefore, this synthesis method can obtain high surface area and unique morphology, and make the material more photodegradable. Secondly, we have established a simple and scalable method for the preparation of tubular Shi Moxiang C3N4 (TGCN). The unique tubular morphology is based on the construction of the basis. In this paper, we first treat melamine with concentrated nitric acid. In this paper, the tubular TGCN is used as the electrode material of the supercapacitor for the first time and its electrochemical energy storage performance is tested. At 6 mole of potassium hydroxide solution, the capacitance of the 0.2A/g current density is 233 F/g, the excellent performance is attributed to the high surface area (182.61 m2/g) and the existence of nitrogen elements. In addition, after 1000 cycles. The capacitive retention rate is still up to 90%., and the properties of TGCN photocatalytic degradation of methylene blue (MB) and methylene orange (MO) are tested under visible light. Compared with the bulk phase GCN, TGCN shows good photocatalytic activity and stability. The high catalytic activity of.TGCN materials is derived from the high surface area, which can provide more active site.TGCN in super electricity. The good performance of the container and photocatalysis makes it a promising material in the field of energy storage and clean environment. Then, we have developed a simple, efficient, scalable method for preparing GCN nanowires as supercapacitor electrode materials and photocatalysts. The advantages of the one dimensional structure of GCNNF1 inner rice are as follows: 1, nitrogen content Higher electrical conductivity and electrochemical performance; 2, a high surface area can provide a larger electrode - electrolyte contact area, promote visible absorption and material transfer, and further increase the redox potential. Therefore, GCNNF is used as a supercapacitor electrode material at 0.1 mole of electrolyte, 1 A/g current density. For 263.75 F/g, the retention rate of capacitance after 2000 cycle is still up to 93.6%. Even at high current density (10 A/g), the capacitance can reach 208 F/g, and the retention of capacitance is still up to 89.5%.. Compared with the bulk graphite C3N4 (GCN), GCNNF shows higher photocatalytic activity when it degrade RhB, and the degradation rate constant is higher than that of bulk graphite C3N4 (GCN). ) 4 times the photocatalyst, the main result is that GCNNF has a higher surface area, a suitable energy band and less defects. As a cheap precursor, the method of melamine synthesis of GCNNF is harmless and without the use of template. The product GCNNF has excellent performance in supercapacitor and photocatalytic degradation. It is expected to be good. It is used in the field of energy storage and environmental protection. After the use of TGCN and GCNNF materials with this structure to explore the influence of the morphology of graphite phase carbon nitride (GCN) on the catalytic performance, the activity of oxygen reduction reaction (ORR) in the alkaline electrolyte of two morphologies of carbon nitride (ORR) is studied. The tubular GCN material is reduced to oxygen in the dissolved oxygen. The starting potential of the reaction (ORR) is close to the commercial Pt/C material. In addition, compared with Pt/C, the tubular GCN shows higher stability and methanol tolerance than Pt/C, and is suitable for the application of fuel cells. Finally, this paper develops a simple, large-scale production low temperature chemical method to prepare C0304 modified graphite phase carbon nitride (GCN) nanotubes. The strong synergistic effect between graphite phase carbon nitride (GCN) and C0304 makes it a bifunctional catalyst for the reaction of oxygen evolution (OER) and hydrogen evolution (HER). High surface area, unique structure and composite components make C03O4@GCN have more easy to contact oxidation-reduction catalytic sites. For OER reaction, IrO2 and RuO2, Co3O4@GCN na The rice composite exhibits a higher overpotential (0.12 V) and current density (147 mA/cm2) and better durability in alkaline electrolyte. In addition, the Co3O4@GCN nanocomposites also exhibit lower overpotential and stable current density in the HER reaction. The prefabricated Co3O4@GCN nanocomposites are in large-scale photodissociation water and The field of fuel cells is more attractive than precious metals.
【学位授予单位】：北京理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ127.11

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