钽基材料的控制合成及其对小分子醇类电催化氧化性能研究

发布时间：2018-03-22 23:35

本文选题：直接醇类燃料电池　切入点：Ta基催化材料　出处：《内蒙古大学》2017年硕士论文　论文类型：学位论文

【摘要】：直接醇类燃料电池(DAFCs)由于不经过燃烧便可直接通过电化学的形式将化学能转化为电能,因此对环境污染很小,由于DAFCs不受卡诺循环的限制而具有高的效率,因此对于解决目前环境污染严重,能源短缺等问题具有重大的研究意义。DAFCs在发展过程中面临的最严重问题是催化剂对醇类的电催化活性低。目前,阳极醇类的氧化电极大多采用Pt或Pt基材料。一方面Pt材料的资源短缺、价格昂贵;另一方面,Pt基材料容易发生醇类氧化中间产物CO中毒,降低了 DAFCs催化剂的利用率。因此,研究高效低廉的催化剂是降低其成本促进其商业化发展的重要途径。本文正是从催化剂材料着手,研究了一系列以Ta基材料为主的催化剂:五氧化二钽负载Pd纳米粒子(Pd/Ta_2O_5)、石墨烯-五氧化二钽负载Pd纳米粒子(Pd/Ta_2O_5-RGO)以及钽酸铁与氮掺杂碳化铁材料的复合(FeTa_2O_6-Fe3C-N),以提高其对小分子醇类(甲醇、乙醇、乙二醇)的电催化活性,以及抗CO中毒能力。研究内容主要有以下几个方面:(1)采用回流法制备两相催化剂Pd/Ta_2O_5,通过X-射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)以及高分辨透射电子显微镜(HTEM)对样品的晶形、形貌等进行了测试。并通过电化学测试技术(循环伏安法、计时电流法、交流阻抗法等)对该催化剂在酸性条件下测试,结果表明该催化剂对甲醇、乙醇、乙二醇均有较好的电催化活性。(2)在对Pd/Ta_2O_5研究的基础上,选择石墨烯做载体,采用回流法合成Pd/Ta_2O_5-RGO催化剂。通过XRD,SEM,TEM,X-射线光电子谱(XPS)等多种手段对催化剂进行了表征。结果显示,由于石墨烯载体的加入使得催化剂的导电性增强、比表面积增大、活性位点增多,所以电化学性能测试显示在碱性条件下,该催化剂对甲醇的电催化活性和稳定性均优于商业Pt/C(10%)。(3)通过一步煅烧法制得复合催化剂FeTa_2O_6-Fe_3C-N,并比较了不同比例复合相的催化效果,结果显示,复合相的催化活性要优于纯相,当FeTa_2O_6和Fe_3C-N按摩尔比为1:2复合时,其催化活性达到最佳,接近于商业Pt/C(10%),继续研究该体系有望做到有高催化活性的非贵金属催化剂材料。
[Abstract]:Direct alcohol fuel cell (Dafs) can convert chemical energy into electric energy directly through electrochemistry without combustion, so it pollutes the environment very little, and DAFCs has high efficiency because it is not restricted by Carnot cycle. Therefore, it is of great significance to solve the problems of serious environmental pollution and energy shortage. The most serious problem in the development of DAFCs is the low electrocatalytic activity of the catalysts for alcohols. On the one hand, Pt materials are short of resources and expensive; on the other hand, Pt based materials are prone to CO poisoning, which reduces the utilization rate of DAFCs catalysts. The research of high efficiency and low cost catalyst is an important way to reduce its cost and promote the development of its commercialization. A series of catalysts based on tantalum pentoxide supported on PD nanoparticles have been studied, such as PD / Ta2O5s, graphene and tantalum pentaoxide-supported PD nanocrystalline Pd / Ta2O5-RGOs, and the composite FeTa2O2O6-Fe3C-NNNs of ferric tantalate and nitrogen-doped iron carbide materials. For small molecules of alcohols (methanol, The electrocatalytic activity of ethanol and ethylene glycol, The main contents of the study are as follows: 1) preparation of two phase catalyst PD / Ta2O5 by reflux method, XRDX, SEM, TEM (TEM) and high resolution transmission electron display (HTEM) by X- ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and high resolution transmission electron display (HRTEM). The crystal shape of the sample by micromirror HTEMs, The morphology of the catalyst was measured by electrochemical techniques (cyclic voltammetry, chronoamperometric method, AC impedance method, etc.). The results showed that the catalyst was applied to methanol, ethanol, ethanol, etc. Ethylene glycol has good electrocatalytic activity. (2) on the basis of the study of Pd/Ta_2O_5, graphene was selected as the carrier to synthesize Pd/Ta_2O_5-RGO catalyst by reflux method. The catalyst was characterized by XRDX SEMX X ray photoelectron spectroscopy (XPS). Because the addition of graphene support enhances the conductivity, the specific surface area and the active sites of the catalyst, the electrochemical performance test shows that, The electrocatalytic activity and stability of the catalyst for methanol were superior to those of commercial PT / C1010and 3) FeTa2O6-Fe3C-Nby one-step calcination method was obtained. The catalytic activity of the composite phase was compared with that of the pure phase, and the results showed that the catalytic activity of the composite phase was better than that of the pure phase. When the molar ratio of FeTa_2O_6 and Fe_3C-N is 1:2, the catalytic activity is the best, which is close to that of commercial PT / C10100.The research on the non-noble metal catalyst materials with high catalytic activity is continued.
【学位授予单位】：内蒙古大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TM911.4

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