碳纳米纤维与纳米晶体复合材料的制备及其电催化产氢性能研究

发布时间：2018-05-04 02:25

本文选题：纳米 + 碳纤维　；参考：《吉林大学》2017年硕士论文

【摘要】：一直以来,人们都认为氢气是一种很重要的清洁能源载体。现在制备产氢最清洁的方法为电催化水裂解制氢,为了减少电解水反应过程中的能源损耗,必须要有一个合适的电催化剂来克服这个反应的能量势垒。然而现在对于电解水产氢反应最有活性的电催化剂是Pt基材料,虽然这些贵金属催化剂产氢效率非常高效,但是由于它们高昂的价格限制了其大规模的广泛应用。因此,我们需要寻找一些清洁低廉、地球资源丰富、高活性并且稳定性好的产氢催化剂来替代这些贵金属材料。在合成或者催化的过程中,纳米晶体聚集或者聚集成块的趋势经常在一定程度上损害材料的总催化活性。因此,为了充分利用纳米催化剂或者是最大化来暴露每个催化单元的活性位点,那么在合成或者催化的过程中要尽量避免纳米催化单元任何可能聚集。另外,电导率也是影响材料总体活性的一个关键因素,因此在合成纳米材料的同时还能提高催化剂的导电性能也是很重要的。因此,本文在这里提出了一种新奇的限制策略分别在多孔的碳纳米纤维上制备出高度分散的CoS_2纳米八面体和CoSe_2纳米粒子,这种高度分散的结构能有效的增加每个催化单元暴露的活性位点。首先我们通过静电纺丝技术和高温热解碳化两个步骤得到包含钴的多孔碳纳米纤维网状结构,随后通过真空原位硫化或者硒化得到我们想要的材料(CoS_2-CFN和CoSe_2-CFN)。CoS_2-CFN和CoSe_2-CFN作为一种非贵金属材料在电解水催化产氢反应中表现出高效且稳定催化特性。即使当它们的催化活性相CoS_2和CoSe_2的负载量仅为0.053 mg cm-2和0.28mg cm-2时,其值分别远远低于先前报道的CoS_2和CoSe_2的材料负载量,CoS_2-CFN和CoSe_2-CFN仍有好的催化活性。这主要是因为它们本身固有的优异催化性质、高度分散的纳米催化单元暴露更多的活性位点和多孔碳纳米纤维提供了更好的导电性能。
[Abstract]:Hydrogen has long been regarded as an important carrier of clean energy. The cleanest way to produce hydrogen is to produce hydrogen by electrocatalytic water cracking. In order to reduce the energy loss in the process of electrolysis, it is necessary to have a suitable electrocatalyst to overcome the energy barrier of this reaction. However, the most active electrocatalysts for electrolytic aquatic hydrogen reactions are Pt-based materials. Although these noble metal catalysts are highly efficient in hydrogen production, their large scale applications are limited due to their high prices. Therefore, we need to find some clean, cheap, rich earth resources, high activity and good stability of hydrogen production catalysts to replace these precious metal materials. In the process of synthesis or catalysis, the tendency of nanocrystalline aggregation or agglomeration often impairs the total catalytic activity of materials to some extent. Therefore, in order to make full use of the nanometer catalyst or to maximize the exposure of the active sites of each catalytic unit, we should try to avoid any possible aggregation of the nano catalytic unit during the synthesis or catalytic process. In addition, the conductivity is also a key factor affecting the overall activity of the materials, so it is important to improve the conductivity of the catalysts while synthesizing nanomaterials. Therefore, in this paper, a novel limiting strategy is proposed to prepare highly dispersed CoS_2 nano-octahedron and CoSe_2 nanoparticles on porous carbon nanofibers, respectively. This highly dispersed structure can effectively increase the number of active sites exposed to each catalytic unit. First, we get the porous carbon nanofiber network structure containing cobalt by electrospinning technology and pyrolytic carbonization at high temperature. The desired materials, Cos _ 2-CFN, CoSe_2-CFN).CoS_2-CFN and CoSe_2-CFN, were obtained by in situ vulcanization or selenization in vacuum. As a non-precious metal material, Cos _ 2-CFN and CoSe_2-CFN exhibited high efficiency and stable catalytic properties in hydrogen production catalyzed by electrolytic water. Even when the loading amount of CoS_2 and CoSe_2 is only 0.053 mg cm-2 and 0.28mg cm-2, their values are much lower than those of CoS_2 and CoSe_2 reported previously. CoS2-CFN and CoSe_2-CFN still have good catalytic activity. This is mainly due to their inherent excellent catalytic properties, highly dispersed nano-catalytic units exposed to more active sites and porous carbon nanofibers to provide better electrical conductivity.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TQ116.2

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