【作者】 杨娟；

【导师】 谭必恩；

【作者基本信息】 华中科技大学 ， 高分子化学与物理， 2018， 硕士

【摘要】 多孔碳材料因其前体来源广泛、制备成本低、良好生物相容性和化学稳定性而广泛应用于气体吸附与分离、水净化、催化和电化学领域。影响多孔碳材料性能的主要因素是杂原子掺杂、比表面积及孔结构。作为CO2吸附剂,高比表面积和微孔结构能提高碳材料CO2吸附量;杂原子能增加材料对CO2的亲和力,提高CO2/N2选择性。应用于电化学,杂原子可有效地改变碳骨架的电子结构和表面化学性质,促进碳表面上的电化学反应;多级孔结构(微孔、介孔和大孔)可通过缩短扩散路径促进O2和电解质离子的输送;较高比表面积可增加多孔碳材料有效催化活性位点密度。微孔有机聚合物(MOPs)是由C、N、O、H等轻元素组成、具有高比表面积、含有丰富微孔结构的一类聚合物。大部分MOPs具有刚性的芳香环结构,不需要额外的交联或预氧化,在高温下碳化骨架能保留微观结构,形成多孔碳材料。MOPs的聚合物设计和化学合成多样性和灵活性,以及自身的孔结构及形貌特点,为设计和制备多孔碳材料提供新思路。本文选用六醛基苯氧基环三磷腈和不同胺类单体,采用席夫碱反应一步法合成含有N、P杂原子的多孔有机聚合物,反应简单且不涉及任何金属催化剂。然后直接高温热解,获得高比表面积的N,P掺杂多孔碳材料。通过扫描电子显微镜(SEM),拉曼光谱(Roman),X射线光电子能谱(XPS),比表面积及孔径分析仪等测试方法表征材料的形态、结构和组成。其中C-POP-2-900在压力1 bar,273 K和298 K温度下均有最高的CO2吸附量,分别为18.6 wt%和12.2 wt%。并且,这种N,P掺杂的多孔碳材料表现出高电催化性能,例如这种催化剂在ORR的应用中支持4-电子转移,同时与Pt/C相比具有优异的稳定性和更高的甲醇耐受性。这些结果表明本方法在制备具有电催化性的多杂原子掺杂碳材料方面前景十分广阔。此外,关于多孔碳材料在电化学领域的研究主要集中在控制材料的孔结构与杂原子掺杂,在微观形貌对于电催化活性的影响的研究十分有限。本文以氨基修饰的Si O2为模板,制备Si O2@POP的核壳结构,然后高温碳化,刻蚀模板,形成N,P掺杂的空心碳球,拟研究形貌对于ORR催化性能的影响。通过优化实验过程,尽管未能制备出预先设计的空心碳球,但是优化过程还是具有一定趋势,仍需进一步探索。更多还原

【Abstract】 Porous carbon materials have been widely applied in gas adsorption and separation,water purification,catalysis and electrochemistry due to their wide range of precursor sources,low cost of preparation,good biocompatibility and chemical stability.The main factors influencing the performance of porous carbon materials are heteroatom doping,porous structure and specific surface area.As a CO2 adsorbent,high specific surface area and microporous structure can increase the carbon materials CO2 uptake,and heteroatoms can increase the affinity of the material for CO2 and increase the CO2/N2 selectivity.For electrochemical applications,the doped heteroatoms can effectively modify the electronic structures and surface chemical properties of the carbon networks,facilitating the electrochemical reaction on the carbon surface;hierarchical porous architecture(including micro-,meso-and macropores)can facilitate the O2 and electrolyte ions transportation by shortening the diffusion pathways;the large surface area can increase the effective catalytically active sites of porous carbon materials.Microporous organic polymers(MOPs)as a class of polymers that consist of light elements such as C,N,O,and H,have a high specific surface area and rich microporous structures.Most MOPs have rigid aromatic structure,which can retain a microstructure under high temperature carbonization to form porous carbon material without additional cross-linking or pre-oxidation.The diversity and flexibility of polymer design and chemical synthesis of MOPs,as well as their own pore structure and morphology characteristics,provide new ideas for the design and preparation of porous carbon materials.In this thesis,Hexakis(4-formylphenoxy)cyclotriphosphazene and different amine monomers were selected.Schiff base reaction was used to synthesize porous organic polymers containing N,P heteroatoms in one step.The procedure is facile and non-metal involved.N,P-doped porous carbon material with large specific surface area was obtained after directly pyrolysis.The morphology,structure and composition of the materials were characterized by scanning electron microscopy(SEM),Raman spectroscopy,X-ray photoelectron spectroscopy(XPS),and Specific surface area and pore size analyzer.Among them,C-POP-2-900 shows the highest CO2 adsorption capacity at pressures of 1 bar,273 K and 298 K,which were 18.6 wt% and 12.2 wt%,respectively.This N,P-doped porous carbon materials exhibits favorable activity towards ORR with better long-term durability and higher tolerance to methanol crossover than the commercial Pt/C reference electro-catalyst.Therefore,this method is promising in the preparation of multi-heteroatom doped carbon materials for electrochemical applications.In addition,the research in the electrochemical field of porous carbon materials mainly focuses on controling the pore structure and heteroatom doping,while the research on the influence of microscopic morphology on electrocatalytic activity is rarely reported.In this study,core-shell structure of Si O2@POP were prepared by Schiff base reaction with aminomodified Si O2 as a template.After carbonizing at high temperature and etching the template N,P-doped hollow carbon spheres were formed.By optimizing the experimental process,although the pre-designed hollow carbon spheres were not prepared,the optimization process still had a certain trend and still need further exploration.更多还原