MOFs及其衍生物的制备与电催化性能研究

发布时间：2018-03-16 21:44

本文选题：金属-有机骨架配合物　切入点：电催化　出处：《哈尔滨工业大学》2017年博士论文　论文类型：学位论文

【摘要】：设计高效催化剂材料是优化新型能源转化装置(如金属-空气电池)和提高电解水性能的核心。虽然贵金属催化剂铂(Pt)和钌(Ru)有高的催化活性,但是其高昂的价格和差的稳定性严重阻碍了它们的大规模应用。因此,制备高效且价格低廉的非贵金属催化剂材料替代商业贵金属催化剂对于推动新型能源转换装置的大规模使用以及商业化进程有着非常重要的意义。本论文以金属-有机骨架配合物为原材料,通过维度控制和金属组成及比例调节等手段制备了一系列单金属和双金属组成的尺寸、结构均一的金属-有机骨架配合物。由于金属-有机骨架配合物材料具有大的比表面积、均一的孔道和周期性的元素排列等特点,制备的MOFs基非贵金属催化剂展示出了优异的电催化性能,超越了商业贵金属Pt/C或者Ru O2,具有极大的实际应用前景和商业价值。更重要的是,结合原位同步辐射技术和密度泛函理论等手段对所制备材料表面发生电催化过程的机理进行了深入探究。具体研究内容如下:采用水热法制备了形貌固定且尺寸均一的单金属-有机骨架配合物,进而通过碳化铁基金属有机骨架化合物前驱体法得到了Fe掺杂的多孔碳材料,该材料很好地保持了前驱体MOFs的骨架结构和形貌。进而,研究了碳化有机骨架配合物在氧还原反应中的电催化性能。研究表明所制备的碳化单金属-有机骨架配合物材料表现出了高的催化活性,较好抗甲醇活性和电催化稳定性。而且,论文进一步研究了金属-有机配合物的尺寸效应和碳化温度对其电催化活性的影响,研究表明尺寸和碳化温度对提升材料的氧还原性能是十分关键的。更重要的是,装有碳化单金属MOF催化剂的甲醇燃料电池的输出功率为22.2 m W/cm2,是相同测试条件下装有商业Pt/C的电池装置的1.7倍。通过超声法在室温下制备了一系列结构一致且厚度均一(~3.1 nm)的超薄金属-有机骨架配合物纳米片,并对其电催化氧析出反应的性能进行了研究。研究表明双金属Ni Co金属-有机配合物纳米片对氧析出反应表现出了优异的电催化活性,极高的法拉第效率和超长时间的稳定性。需要强调的是,其活性和稳定性都超过了商业贵金属催化剂Ru O2,表现出了极大的实际应用前景。而且,结合同步辐射X-射线吸收谱和密度泛函理论对该催化剂结构和性能的关系进行了深入研究,研究表明超薄金属-有机配合物纳米片表面有大量不饱和配位中心。制备了一系列金属位点可控的双金属-有机骨架配合物MOFs-74并且将其作为催化剂用于电催化产氧反应中。通过精确调节双金属MOFs-74体系中的金属比例,Ni1Co1-MOFs-74催化剂在氧析出反应中表现出了低的过电位和优异的稳定性。通过结合密度泛函理论计算确定了双金属体系的主要活性中心、反应过程中的决速步骤以及清晰地呈现了对氧析出反应自由能的调节过程。最后,将催化剂喷涂到碳纸上制备成实际氧电极用于电解水产氧,表现出了极好的活性和超长时间稳定性(100 h测试性能保持96%以上)。
[Abstract]:Design of high efficiency catalyst material is the optimization of the new energy conversion devices (such as metal air batteries) and improving core water electrolysis performance. Although platinum (Pt) and ruthenium (Ru) has high catalytic activity, but its high price and poor stability seriously hindered the large-scale application of them. Therefore, non noble metal catalyst materials for the preparation of highly efficient and inexpensive alternative to commercial noble metal catalyst has a very important significance for the promotion of new energy conversion devices and large-scale use of the commercialization process. In this paper, metal organic complexes as raw materials, through the dimensions and control of metal composition and adjust the proportion of components such as a series of single and double the size of the metal metal applied to synthesize uniform structure, the metal organic framework. The metal organic framework materials have large surface area, uniform pores The periodic arrangement of elements and characteristics of MOFs based noble metal catalysts prepared from show excellent electrocatalytic properties, beyond the commercial noble metal Pt/C or Ru O2, has great application prospect and commercial value. More importantly, the combination of in situ prepared for the mechanism of electro catalytic process material surface conduct in-depth research on the technology and means of the density functional theory of synchrotron radiation. The main research contents are as follows: single metal shape fixed and uniform size organic complexes were prepared by hydrothermal method, and then through the carbonization of Fe based metal organic framework compound precursor obtained by the method of Fe doped porous carbon material, the material is keep the skeleton structure and morphology of the precursor of MOFs. Then, on the carbonization of organic framework on the electrocatalytic performance for oxygen reduction reaction. The results indicated that the single genus of gold by carbonization - organic framework materials exhibit high catalytic activity, good anti methanol activity and electrocatalytic stability. Moreover, the paper further studies the influence of size effect and carbonization temperature of metal organic complexes on the catalytic activity, studies show that the size and performance of materials to enhance the carbonation temperature reduction of oxygen is very important. More importantly, the output power of methanol fuel cell with carbide single metal MOF catalyst is 22.2 m W/cm2, is 1.7 times the battery device under the same testing conditions with commercial Pt/C. By ultrasonic method at room temperature in the preparation of a series of structural consistency and uniform thickness (~3.1 nm) thin metal organic framework nanosheets, and the electrocatalytic oxygen evolution reaction were studied. The results show that the double metal Ni Co metal organic complexes nanosheets on oxygen precipitation reaction showed excellent Electrocatalytic activity, stability of high efficiency and long time. Faraday needs to be emphasized is that the activity and stability than commercial noble metal catalyst Ru O2, showed great practical application prospect. Moreover, combining with the in-depth research of spectrum and density functional theory X- ray absorption relationship on the structure and properties of the catalyst the synchrotron radiation studies show that ultra-thin metal organic complexes nanosheets in surface of unsaturated coordination center. Preparation of double metal - a series of metal sites controlled organic framework and MOFs-74 as the catalyst for the catalytic reaction. The oxygen produced by precisely adjusting the proportion of double metal metal MOFs-74 system the Ni1Co1-MOFs-74 catalyst in the oxygen evolution reaction showed low overpotential and excellent stability. By combining density functional theory calculations to determine the bimetallic system The main activity center during the reaction step and clearly presents the regulation process of oxygen evolution reaction free energy. Finally, the catalyst is sprayed to carbon paper prepared into actual oxygen electrode for electrolysis of water to oxygen, showed high activity and long time stability (keep 100 h test performance 96% above).

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O643.36

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