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类型 基础研究 预答辩日期 2017-11-19
开始(开题)日期 2016-05-23 论文结束日期 2017-09-05
地点 东南大学化工新楼315 论文选题来源 国家自然科学基金项目     论文字数 5.8 (万字)
题目 基于分子设计的非贵金属氮掺杂碳材料的催化性能研究
主题词 氮掺杂碳,配合物,催化,氧还原,肼氧化
摘要 掺杂碳纳米材料通常具有极化的电子云分布、优异的电子传输性能、高的比表面积和稳定的结构。采用非贵金属元素M(Fe、Co和Cu等)和N掺杂的碳纳米材料(M-N/C),不仅可以保留碳纳米材料本身的一些特性,还可通过改变前驱体/配体结构等方式来调控M与N的电子和化学结构,从而实现对纳米碳材料相关性能的提升,使其具备和某些贵金属,例如,铂和钯,以及M-N配合物小分子类似的催化性能,并有望取代取代贵金属用于能源转化与多相有机催化等领域。然而,系统地研究并建立前驱体/配体结构、M-N/C结构与性能间内在联系仍是一个重大挑战,很大程度上限制了M-N/C的进一步发展。这其中的一个重要原因在于当前的高温热解体系相对复杂而低温策略制备的M-N/C性能往往较差,难以满足其实际应用。本论文旨在简化制备体系的前提下,分别通过高温和低温策略在分子水平上设计和制备高性能非贵金属氮掺杂碳材料,研究其在能源转化与仿生催化等领域的相关应用;通过调节分子结构,实现对非贵金属氮掺杂碳材料的理化结构调控,建立前驱体/配体结构、催化剂结构与催化剂活性间的内在联系,并探讨相关催化机理。本论文的研究内容主要分以下四部分: 1、采用离子液体作为单一前驱物,通过高温热解法制备高催化性能Fe、N掺杂碳材料,该体系无需模板、负载和多步热解。利用离子液体结构易调控优势,系统研究了前驱物分子结构(取代基和含铁对离子)、催化剂结构(孔结构、掺杂N类型、石墨化程度和导电性)与催化剂性能三者之间的内在联系,并通过该规律成功预测并合成了部分关键性能优于商业化铂碳的Fe、N掺杂碳材料。 2、进一步发现通过高温热解咪唑基离子液体制备的Fe、N掺杂碳材料能够在室温水溶液体系中直接利用空气中的氧气单氧化和脱氢底物。与天然的氧化酶相比,该催化剂不仅在高温、有机相以及极端的pH下依然可以保持高的催化活性,而且其异相的特征还有易分离和循环重复使用的优点。机理研究表明,Fe-N是催化活性中心,其在还原活化氧气氧化底物的过程中会形成了反应型活性氧(ROS)。基于这些发现,在正常生理条件下,该催化剂被进一步成功应用于杀伤肺癌细胞。这项工作为Fe、N掺杂碳材料在仿生催化模拟氧化酶的新陈代谢功能与机制研究、工业氧化以及疾病治疗等领域的应用提供了新的思路。 3、受漆酶结构与性能间关系的启发,利用Cu-N间的配位作用以及非共价π-π相互作用,在分子水平上将Cu-N配位聚合物组装到商业化炭黑的表面,构建了一种可高效催化氧气还原(ORR)和肼氧化(HOR)的双功能电化学催化剂。发现Cu-N聚合物骨架中的3,3’-二氨基联苯胺(3,3’-Diaminobenzidine,DAB)配体展现了类似于漆酶中Cys-His配体的功能。由于DAB配体富电子和π共轭的结构特征,使其可与炭黑间形成长程π-π相互作用并协效调控Cu-N配位中心的电子结构和催化过程中的多步电子转移过程。由于无需高温裂解,此催化剂具有相对明确的分子结构,从而简化了ORR催化机理的研究,我们发现其催化ORR过程中形成了1O2、O2?? 和 OH?自由基。 4、通过调节配体的共轭性和配位基团种类,设计合成了三种具有不同分子结构的Cu基双功能ORR和HOR电化学催化剂,并系统研究了配体结构、催化剂结构与催化活性间的关系。发现减弱配体的共轭性、增加配体中配位氨基的数目不仅有利于暴露催化剂活性位点和提高催化剂的亲水性,还有助于优化催化剂中Cu的电子结构,这些因素共同促进了Cu基催化剂性能的改善。
英文题目 Molecular Design of Precious Metal-Free Doped Carbon for Catalysis
英文主题词 N-doped carbon, complex, catalysis, oxygen reduction, hydrazine oxidation
英文摘要 Doped carbon nanomaterials have polarized electron cloud distribution, excellent electron transport properties, high specific surface area and stable structure. Particularly, for precious metal-free N-doped carbon nanomaterials (M-N/C, M represents Fe, Co and Cu, etc.), it still retains some characteristics of pure carbon nanomaterials. Moreover, both the electronic/chemical structures of M and N could be rationally tuned to improve the performance of M-N/C by changing preparation methods and the structure of precursors/ligands. Such a class of M-N/C are even similar to some precious metals such as Pt/Pd and M-N complexes in catalysis. Accordingly, it would be a promising candidate for replacement of noble metals and could be applied in many fields ranging from energy conversion to heterogeneous organic catalysis. However, it is difficult to systematically study and establish the structure-activity relationships between the structure of precursors/ligands and the structure and activity of M-N/C via a conversional pyrolysis and low temperature stratagy, hinding the development and broad application of M-N/C. It is mainly ascribed to the fact: (a) the high temperature pyrolysis system is relatively complex; (b) M-N/C, prepared by the low temperature strategy, has poor activity, limiting the practical application in the catalytic process. The goal of this dissertation is to design and prepare M-N/C with high performance at the molecular level by high temperature and low temperature, respectively, under the premise of simplifying the preparation system and study their related catalytic activity in energy conversion and biomimetic catalysis. Moreover, the physical/chemical structure of M-N/C is modulated by tuning the structure of precursors/ligands. Accordingly, The relationship between the structure of precursors/ligands and the structure/activity of M-N/C is systematically studied and the related catalytic mechanism is further disclosed. The detailed works are summaried as follows: (1) A class of high efficient Fe-N/C electrocatalysts derived from versatile imidazolium-based ionic liquids (ILs) were developed. Without any supports, templates, or multi-step of prolysis, the as-prepared Fe-N/C catalysts exhibited superior ORR activities than the state-of-the-art Pt/C in alkaline electrolytes. More interstingly, due to the versatile configuration of the imidazolium-based ILs precursors, a diverse range of catalyst structures was sucessfully modulated. Based on this, it was revealed unambiguously that electric conductivity, type/amount of N-dopants, and “effective porosity” (not conventional total surface area) jointly determined electrocatalytic activities. A pivotal radar chart was further proposed to successfully predict the ORR activity merely by structures of Fe-N/C catalysts. (2) The as-prepared Fe-N/C showed an intrinsic cytochrome P450 oxidase-like activity in oxidation of various organic substrates using O2 at room temperature in aqueous solution. Moreover, the Fe-N/C surpassed natural oxidase by high activity and stability, and ease of separation and recyclability even in organic solvents, high temperature and extreme pH. The Fe-N center was proved to be the active site that reductively activated O2 by spontaneous generation of ROS species. Based on these findings, the Fe-N/C was further successfully exampled to kill live and proliferative lung cancer cells under normal physiological conditions. It would open up a promising platform of Fe-N/C in biomimetic catalysis ranging from simulation of oxidase metabolism to industrial oxidation processes, and to disease treatment. (3) Inspired by structure-property relationships of laccases (a kind of macromolecular biological catalysts), we report a facile molecular assembly of Cu(3,3’-diaminobenzidine) polymeric complex on carbon black via Cu-N complexing and π-π interaction as a highly efficient bifunctional electrocatalyst for ORR and hydrazine oxidation reaction (HOR), two half reactions for hydrazine fuel cells. Similar to the function of the Cys-His group in natural laccases, the 3,3’-diaminobenzidine ligand in the proposed polymeric catalyst synergistically adjusted the electronic structure of Cu-N complex center and mediated a multiple-electron transfer cooperatively with carbon black via a long-range π-π interaction, owing to its electron-reservation and π-conjugated properties. This work may provide a new way to design highly efficient biomimetic noble-metal free electrocatalysts with well-defined and tunable structures. (4) Three kinds of Cu-based bifunctional ORR and HOR electrochemical catalysts with different structures were designed and synthesized by tuning π-conjugation and coordination groups of ligands. The relationships between the structure of ligands and the structure/activity of catalysts were systematically studied. The results showed that reducing the π-conjugation of ligands and increasing the number of coordinated amino groups of ligands were not only beneficial to both expose the active sites and improve the hydrophilicity of catalysts, but also to optimize the electronic structure of Cu in catalysts for adsorption of catalatic intermediates. Both of these would lead to improve the activity of Cu-based catalysts in the ORR/HOR process.
学术讨论
主办单位时间地点报告人报告主题
张袁健教授课题组 2017年03月24日 新化工楼503室 何飞 Cu-N配位高聚物的结构与ORR/HOR性能间的关系
刘松琴教授课题组 2016年06月25日 新化工楼503室 何飞 Fe-N/C:模拟P450酶氧化底物
刘松琴教授课题组 2015年12月12日 新化工楼503室 何飞 炭黑负载的Cu配位高聚物的氧还原性能
刘松琴教授课题组 2014年10月18日 老化工楼大会议室 何飞 基于离子液体衍生的Fe-N/C的氧还原性能
东南大学化学化工学院 2014年9月15日 老化工楼大会议室 Zoe Schnepp Materials from biomass: Iron-catalysed graphitization of sawdust to make carbon nanotubes
东南大学化学化工学院 2016年06月02日 九龙湖校区第一教学楼111 Markus Antonietti Carbon Nitride and its family: a game changer on materials chemistry
东南大学化学化工学院 2016年05月13日 九龙湖校老楼307 黄进 纤维素纳米晶的表面修饰及改性材料高性能化探索
东南大学化学化工学院 2016年04月19日 九龙湖校老楼307 Menny Shalom Carbon Nitride and nickel-based materials for artificial photosynthesis
     
学术会议
会议名称时间地点本人报告本人报告题目
第二届国际电化学能源技术会议 2016年8月17日 加拿大,温哥华 Non-precious Fe-N/C catalysts derived from ionic liquids for oxygen reduction reaction
第一届东南大学分析化学博士生论坛 2014年12月06日 南京 Self-Supported Non-precious Fe-N/C Catalysts derived from Ionic Liquids for Highly Efficient Oxygen Reduction Reaction
     
代表作
论文名称
Ionic Liquid-Derived Fe?N/C Catalysts for Highly Efficient Oxygen Reduction Reaction Without Any Sup
 
答辩委员会组成信息
姓名职称导师类别工作单位是否主席备注
陈金华 正高 教授 博导 湖南大学
牛利 正高 研究员 博导 长春应用化学研究所
王进义 正高 教授 博导 西北农林科技大学
刘松琴 正高 教授 博导 东南大学
孙岳明 正高 教授 博导 东南大学
林保平 正高 教授 博导 东南大学
周建成 正高 教授 博导 东南大学
      
答辩秘书信息
姓名职称工作单位备注
卫伟 正高 教授 东南大学