超薄有机纳米片的可控合成及其在非均相催化中的应用

发布时间：2018-03-16 15:38

本文选题：金属有机框架　切入点：碳化氮　出处：《中国科学技术大学》2017年博士论文　论文类型：学位论文

【摘要】：自石墨烯发现以来,具有原子或者分子厚度的过渡金属卤化物(TMDs),黑鳞(BPs),贵金属纳米片等二维材料便受到了科学家们的广泛关注。相对于其类似物,二维材料具有独特的物理化学性质。但是目前很多技术性问题(大规模制备、易堆叠等)仍然制约着二维材料的进一步发展。我们开展的研究主要就集中在如何高效制备二维材料上。一方面,基于层状金属有机框架(MOF)晶体,我们通过配体层间插入和化学还原断裂的方式,成功地制备出二维(2D)金属有机框架(MOF)纳米片。此方法的新颖性在于,通过化学配位键的作用,含有化学可断裂基团的试剂(4,4'-dipyridyldisulfide)可以插入到层状金属有机框架(MOF)的层与层之间。在含膦的亲核试剂作用下,有机配体中二硫键可以快速地发生还原反应。另外,在一定程度上,二硫键的还原进程可以调控二维(2D)金属有机框架(MOF)纳米片的厚度。化学剥离在室温下可以高效的进行,并可以近57%的总收率获得二维(2D)金属有机框架(MOF)纳米片。而且制备出的二维(2D)金属有机框架(MOF)纳米片可用于非均相的光催化氧化反应。另一方面,我们通过无机强酸辅助的溶剂热剥离法,成功地利用层状碳化氮材料制备出相应的纳米片。这种剥离方法不仅简单高效,而且无机强酸可以通过离心收集循环使用。值得一提是,这种剥离方法适用于不同碳氮比例的层状碳化氮材料(g-C3N4,C2N,Aza-CMP)。制备的g-C3N4纳米片可用于光催化产氢中,且其产氢效率在同等条件下明显高于剥离前的样品。此外,化石燃料的燃烧导致了全球的能源危机及环境污染问题,这在很大程度上促进了可再生能源系统和能源储存系统的发展,如可充放电的金属空气电池和可再生的燃料电池等。由于具有很高的理论能量密度,金属空气电池在未来的电学设备上具有很广阔的应用空间。其中可充放电的锌空电池以其特有的优点,如环境友好和安全高效等,在众多的金属空气电池中使其成为一种理想的选择。现阶段电催化研究领域的热点集中在,1)如何降低电化学催化剂中贵金属(如Pt,Ir或者Ru)的用量;2)直接用其他材料取代贵金属的使用,同时电化学催化剂依然保持良好的催化性能。在众多的研究方向中,无贵金属参与的低成本、高活性、高耐受性和使用寿命长的电化学催化剂的开发已成为主流研究。现阶段电化学催化剂的设计主要有以下两种思路:1)杂原子掺杂。理论计算和实验数据都表明,使用杂原子替换掉晶格中的sp2碳原子可以调节材料的电子分布状态及材料的给电子能力,并由此提供氧气吸附和氧气还原的活性位点,从而达到提高电化学催化剂的催化活性。2)金属纳米粒子的复合。以石墨烯为例,这类碳材料具有很大的比表面积,且结构稳定。如果我们使用高催化活性的金属纳米粒子与之复合,则得到的复合材料同时具备两种复合材料的优点,而且会具有更加优异的催化性能。我们基于以上两点思路,开发了一种高效的双功能催化剂(ORR和OER),并成功的用这种电化学催化剂组装了三电极的锌空电池。与标准电化学催化剂Pt/C及RuO2相比,我们开发的电化学催化剂能量利用效率有明显的提高。由于制备方法简单,原料便宜易得,催化性能高效等优点,我们开发的电化学催化剂有望在未来的锌空电池的实现大规模应用。
[Abstract]:Since the discovery of graphene, transition metal halides with atomic or molecular thickness (TMDs), black scales (BPs), noble metal nano films such as two-dimensional materials they received extensive attention from the scientists. Compared with its analogues, two-dimensional materials with unique physical and chemical properties. But there is a lot of technical problems (Large scale the preparation, easy stacking) still restricts the further development of the two-dimensional material. Our research mainly focuses on how to prepare a two-dimensional material efficient system. On the one hand, the layered metal organic framework (MOF) based on the crystal, we restore the fracture way through ligand intercalation and chemistry, successfully prepared a two-dimensional (2D) metal organic framework (MOF) nanosheets. Novelty of this approach is that by chemical coordination bonding, chemical reagent containing fracture group (4,4'-dipyridyldisulfide) can be inserted into the layered metal organic The framework (MOF) between layer and layer. The phosphine nucleophiles under the action of two disulfide bonds in organic ligands can be rapidly reducing reaction. In addition, in a certain extent, the reduction process of two disulfide can control the two-dimensional (2D) metal organic frameworks (MOF) the thickness of the nanosheets. Chemical peel can be efficiently carried out at room temperature, and the total yield of nearly 57% can obtain two-dimensional (2D) metal organic framework (MOF) and nanosheets. The prepared two-dimensional (2D) metal organic framework (MOF) nano sheet can be used for non homogeneous photocatalytic oxidation reaction. On the other hand, we solvent thermal assisted inorganic acid stripping method, the successful use of layered materials to prepare carbon nitride nanosheets accordingly. This stripping method is not only simple and efficient, and can be collected by centrifugation of inorganic acid recycling. It is worth mentioning that this method is suitable for stripping ratio of carbon to nitrogen layer The shape of carbide nitride materials (g-C3N4, C2N, Aza-CMP). G-C3N4 nanosheets prepared for photocatalytic hydrogen production and hydrogen production efficiency, under the same condition was significantly higher than that before peeling samples. In addition, the burning of fossil fuels has led to the global energy crisis and environmental pollution problems, which promote the development of renewable energy system and energy storage system to a great extent, such as fuel battery charge and discharge of metal air battery and renewable. With the theory of high energy density, metal air battery has a broad application space in the electrical equipment of the future. The zinc air battery can be charged and discharged with its unique advantages such as, environment friendly and high efficiency, the metal air battery in many make it become an ideal choice. Now the hot point in the field of catalysis power concentrated in 1), how to reduce the electrochemical catalytic agent of noble metal Genera (such as Pt, Ir or Ru) dosage; 2) to replace the direct use of precious metal or other materials, and the electrochemical catalyst still maintains good catalytic performance. In the numerous research directions, low cost, precious metals in high activity, the development of electrochemical catalyst high resistance and long service life. Has become the mainstream of the design stage. The electrochemical catalyst mainly has the following two ways: 1) was doped. The theoretical calculation and experimental data show that the use of heteroatoms to replace SP2 carbon atoms in the lattice can adjust the material distribution state of electronic materials and electronic capability, and thus provide active sites for oxygen adsorption and reduction of oxygen, so as to improve the catalytic activity of.2 catalyst for the electrochemical) composite metal nanoparticles with graphene. For example, this type of carbon material has large surface area, and the structure is stable. If I We use metal nanoparticles with high catalytic activity and the composite, composite material is obtained with two kinds of advantages of composite materials, but also has more excellent catalytic performance. We based on the above ideas, a dual function catalyst for efficient development (ORR and OER), and the successful use of this electrochemical catalyst assembly the three electrode of zinc air battery. Compared with the standard Pt/C electrochemical catalyst and RuO2, we developed the electrochemical catalyst energy utilization efficiency is improved obviously. The preparation method is simple, cheap and easily obtained raw materials, has the advantages of high catalytic performance and electrochemical catalyst developed by us is expected in the future of the zinc air battery to achieve large-scale applications.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O643.36;TB383.1

【相似文献】