吲哚类化合物修饰碳载钴催化剂对氧还原催化作用的研究

发布时间：2018-02-28 20:54

  本文关键词： 燃料电池 氧还原反应 吲哚 吲哚羧酸 亲电中心 亲核中心　出处：《浙江大学》2015年硕士论文　论文类型：学位论文

【摘要】：燃料电池由于其能量转换率高和对环境友好等优点而受到广泛关注。阴极氧还原反应(ORR)是制约燃料电池发展和推广的重要因素,传统的ORR催化剂使用的是碳担载铂(Pt/C), Pt具有优良的ORR催化活性,但是Pt是贵金属,资源稀少,价格昂贵,限制了燃料电池的产业化发展,因此开发非贵金属催化剂成为了燃料电池的研究热点之一。本文研究了吲哚和吲哚羧酸修饰碳载非贵金属材料作为ORR催化剂,探讨其在酸性和碱性介质中的催化机理,测试其电化学性能,并用于燃料电池,对其性能和稳定性进行验证。本文采用水热法合成复合催化剂材料M-N/C,并首次采用原位透射电镜对催化剂热处理过程中的形貌和结构变化进行分析,采用傅里叶红外光谱(FT-IR)、X射线粉末衍射仪(XRD)、核磁共振光谱(NMR)、电感耦合等离子体发射光谱(ICP)等分析方法对材料进行分析表征；采用循环伏安法(CV)、旋转圆盘法(RDE)等对材料的电化学性能进行测试。通过对催化剂材料的结构成分和在不同介质中的电化学性能进行分析,推测影响催化剂活性的关键因素。研究表明,吲哚修饰碳载钴催化剂(Co-indole/BP)和吲哚羧酸(吲哚甲酸：ICA,吲哚乙酸：IAA,吲哚丙酸：IPA,吲哚丁酸：IBA)修饰碳载钴催化剂都具有良好的ORR催化活性。Co-IAA/BP在酸性和碱性介质中的的催化剂活性明显高于Co-indole/BP。通过原位透射电镜检测到Co-indole/BP 和 Co-IAA/BP在氩气环境下热处理到900℃的过程中(将热处理后的催化剂分别记作Co-indole/BP (900) 和 Co-IAA/BP (900)),有CO3O4晶体形成,Co-indole/BP (900)和Co-IAA/BP (900)在酸性和碱性介质中均具有更高的ORR催化活性。此外,Co-IAA/BP (900)的氧还原初始电位、动力学电流密度和反应转换电子数都明显高于Co-indole/BP (900)。Co-IAA/BP及Co-indole/BP (900) 和 Co-IAA/BP (900)催化剂在酸性介质下也具有良好的ORR催化活性,是因为在Co-IAA和CO3O4中的氧原子具有孤对电子,能够吸引酸性介质中的质子。在酸性介质中,同时含有亲电中心(CO3O4中的Co)和亲核中心(CO3O4中的O)催化活性中心是其具有良好的ORR催化活性的主要原因。在以上研究成果的基础上,通过直接甲醇燃料燃料电池(DMFC)和直接硼氢化钠燃料电池(DBFC)对Co-IAA/BP (900)催化剂进行了实证,在DMFC中,其放电性能比10%Pt/C要差,但是在DBFC中,其放电性能超过了10%Pt/C,说明Co-IAA/BP (900)可以替代10%Pt/C用于直接硼氢化钠燃料电池中。通过阴极寿命测试表明的热处理后的Co-indole/BP 和 Co-IAA/BP都具有良好的稳定性。
[Abstract]:Fuel cells have attracted wide attention due to their high energy conversion rate and environmental friendliness. The cathode oxygen reduction reaction (ORR) is an important factor restricting the development and promotion of fuel cells. The traditional ORR catalyst is supported by carbon supported platinum (Pt / C), Pt has excellent catalytic activity for ORR, but Pt is precious metal, which is rare in resources and expensive in price, which limits the development of fuel cell industrialization. Therefore, the development of non-noble metal catalysts has become one of the research hotspots in fuel cells. In this paper, indole-and indole carboxylic acid-modified carbon-supported non-noble metal materials were studied as ORR catalysts, and their catalytic mechanism in acidic and alkaline media was discussed. Test its electrochemical performance and use it in fuel cells, In this paper, the composite catalyst material M-N / C was synthesized by hydrothermal method, and the morphology and structure of the catalyst during heat treatment were analyzed by in situ transmission electron microscope (TEM) for the first time. The materials were characterized by FT-IR X-ray powder diffractometer, nuclear magnetic resonance spectroscopy (NMR) and inductively coupled plasma emission spectrometry (ICP). The electrochemical properties of the catalysts were tested by cyclic voltammetry (CV) and rotating disk method (RDEs). The structure and the electrochemical properties of the catalyst materials in different media were analyzed. The key factors affecting the activity of the catalyst were speculated. Indole-modified carbon-supported cobalt catalysts Co-indole-a-bp and indole carboxylic acid (ICA: ICA, indole acetic acid: IAA, indole propionic acid: IPA, indole butyric acid: IBA) all have good ORR catalytic activity. The activity of Co-indole/BP and Co-IAA/BP was obviously higher than that of Co-indole / BP.The results of in situ transmission electron microscopy (TEM) showed that Co-indole/BP and Co-IAA/BP were heat-treated to 900 鈩，

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