兰州大学机构库 >化学化工学院
氧化铈基复合材料的制备及氧析出反应研究
Alternative TitleFabrication of Ceria-Based Composites for Oxygen Evolution Reaction
王玮
Subtype硕士
Thesis Advisor席聘贤
2021-05-28
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name理学硕士
Degree Discipline化学
Keyword静电纺丝 氧化铈基复合材料 氧析出反应
Abstract摘 要 纳米材料的制备与应用成为近年来热门研究领域之一。在不同维度的纳米材料中,有两个维度范围在0.1~100 nm的一维纳米材料由于其优异的热稳定性,电子传输性能及力学性能而具有广泛的应用前景。静电纺丝法作为合成一维纳米纤维的主要途径,在化工催化,造纸,服装,能源,食品等领域有巨大的潜在应用价值。二氧化铈基材料的主要成分氧化铈有着结构稳定性高,易制备等特点,并且在参与三元催化反应,净化汽车有毒尾气,低温水煤气转换反应,应用于氧气渗透膜系统,燃料电池等方面都有出色的表现。将氧化铈基材料应用于电催化已经有过诸多尝试。因而,静电纺丝法制备氧化铈基复合材料可以实现氧化铈与纳米纤维的优势结合。本论文通过静电纺丝与高温热处理分别将四氧化三钴,四硫化三钴,磷化钴与氧化铈复合在氮杂碳纳米纤维上,并在电催化氧析出反应(Oxygen Evolution Reaction,OER)上研究其应用价值。具体工作如下: 1. 先使用静电纺丝法制备钴与铈的复合纳米纤维前驱体,后通过高温煅烧获得钴与氧化铈的复合氮杂碳纳米纤维,最后低温氧化获得钴/四氧化三钴/氧化铈复合氮杂碳纳米纤维。应用于OER反应发现,合成的四氧化三钴与氧化铈复合纳米材料的过电势在10 mA/cm时为355 mV,稳定性在27 h内仅上涨40 mV。经拉曼测试,材料主体有明显的碳的G带振动峰与D带振动峰,说明主体是由碳作为核心骨架元素。碳纤维的形成与高温热解的聚丙烯腈(PAN)有关。由于在前驱体中含有氮元素,因此在高温热解时,氮元素掺杂进了碳骨架,形成氮杂碳纳米纤维。进一步通过透射电子显微镜观察发现,合成的纤维材料有许多孔隙,结合参考文献的说明,推测这可能是氧气侵蚀碳留下的孔。该材料与不含铈的对比材料相比较,10 mA/cm时过电势降低了94 mV。 2. 同样通过静电纺丝法制备钴铈纳米纤维前驱体,用高温处理还原出金属钴,同时产生氧化铈。再通过硫粉硫化获得四硫化三钴与二氧化铈及纳米纤维的复合物,该复合物保持了纤维状主体形貌,上镶嵌了四硫化三钴与二氧化铈复合物的颗粒。在氧析出反应性能测试中,10 mA/cm时过电势为395 mV,稳定性在27 h内几乎不变。虽然硫化物复合材料的过电势高于氧化钴复合材料,但其物相更纯,比起钴/四氧化三钴与氧化铈的复合材料,四硫化三钴与氧化铈的复合材料中不残留钴单质。和不含铈的对比材料相比较,10 mA/cm的过电势降低55 mV。 3. 与硫化物类似,磷化钴氧化铈复合氮杂碳纳米纤维的合成,经历了钴的热还原与高温热解硝酸根和聚合物,形成了钴/氧化铈氮杂碳纳米纤维中间体。再用次磷酸钠做磷源加热时分解放出磷化氢,进行磷化。所得产物在主体上保持了氮杂碳纳米纤维形貌,上附着颗粒为磷化钴氧化铈复合结构。同样用拉曼证实了纤维主体碳元素G带振动峰和D带振动峰的存在。经过氧析出反应测试,10 mA/cm时过电势为382 mV,稳定性在27 h内几乎不变。这样的过电势略好于硫化物,却依然差于钴/氧化钴复合材料,是钴/氧化钴复合材料氧空位优越性的突出表现。硫化物与磷化物的合成结果从侧面体现了硫空位与磷空位的形成和控制难度大。和不含铈的对比材料相比较,10 mA/cm时的过电势下降了46 mV。 关键词:静电纺丝,氧化铈基复合材料,氧析出反应
Other AbstractAbstract The fabrication and application of nanomaterials have become one of the hotest research fields in recent years. Among the nanomaterials with different dimensions, one-dimensional nanomaterials with two dimensions ranging from 0.1 to 100 nm, have a wide application prospect due to their excellent thermal stability, electron transport performance and mechanical properties. Electrospinning, as the main way to synthesize one-dimensional nanofibers, has great potential application value in chemical catalysis, paper making, clothing, energy, food and other fields. Ceria, the main component of ceria-based materials, has the characteristics of high stability of a structure and is easy to prepare. And in the participation of three-way catalytic reactions, the elimination of automobile toxic exhaust, low temperature water-gas shift reaction and the application of oxygen-permeable-membrane system and fuel cells have had excellent performance. There have been many attempts to apply ceria-based materials in electrocatalysis. Therefore, the combination of cerium oxide and nanofibers can be realized by using electrospinning to prepare cerium oxide matrix composites. In this paper, Co3O4, Co3S4, CoP and CeO2 on N-doped carbon nanofibers were composited by the electrospinning and high temperature heat treatment, and studying its application value in the electrocatalytic oxygen evolution reaction (OER). Specific works are as follows: I. The precursors of nanofibers with Co and Ce were prepared by electrospinning firstly, then N-doped carbon nanofibers with Co and CeO2 were prepared by calcined at high temperature, finally Co/Co3O4/CeO2 N-doped carbon nanofibers was obtained by calcined in air at low temperature. When applied to OER, it was found that the overpotential of the composite nanomaterials was 355 mV at 10 mA/cm, and the stability only increased by 40 mV in 27 h. According to Raman results, the material had obvious G band and D band vibration peaks of carbon, indicating that carbon is the core skeleton element of the material body. The formation of carbon fiber was related to the high temperature pyrolysis of polyacrylonitrile (PAN). Because there is nitrogen in the precursor, nitrogen was doped into the carbon skeleton to form N-doped nanofibers at the high temperature process. Further observation by transmission electron microscope showed that there were many pores in the fibrous materials, combined with references, speculating that these pores could be the mark left by the oxidation caused by oxygen. Compared with the contrast material without cerium, the overpotential of the material decreased by 94 mV at 10 mA/cm. II. The precursor of nanofibers with Co and Ce was also prepared by electrospinning method. The cobalt metal was reduced by high temperature treatment and cerium oxide was produced at the same time. Then the composite of Co3S4/CeO2 and N-doped carbon nanofibers was obtained by sulfidation with sulfur powder, the composite maintains a fibrous main morphology, particles of Co3S4 and CeO2 were inlaid on it. In the OER performance test, the overpotential at 10 mA/cm was 395 mV, and the stability is almost unchanged within 27 h. Although the overpotential of sulfide composite is higher than that of cobalt oxide composite, its phase is purer, compared with the composite of Co/Co3O4 and CeO2, there is no residual Co elementary substance in the composite of Co3S4 and CeO2. Compared with the contrast material without cerium, the overpotential of 10 mA/cm was reduced by 55 mV. III. Similar to sulfide, the synthesis of CoP/CeO2 N-doped carbon nanofibers underwent thermal reduction of cobalt and high temperature pyrolysis of nitrate and polymer, the intermediate of Co/CeO2 N-doped carbon nanofibers was formed. Then sodium hypophosphite was used as a phosphorus source to achieve the liberation of phosphine by heating for phosphidation. The main body of the product maintained the morphology of N-doped carbon nanofibers, and the attached particles were the composite structure of CoP and CeO2. The existence of G band and D band vibration peaks of carbon in fibers was also confirmed by Raman method. After OER test, the overpotential at 10 mA/cm was 382 mV, and the stability was almost unchanged within 27 h. The overpotential is slightly better than that of sulfide, but still worse than that of Co/Co3O4 composite, which is the outstanding superiority of oxygen vacancy of Co/Co3O4 composite. The synthesis results of sulfide and phosphide show that the formation and regulation of sulfur vacancy and phosphorus vacancy are difficult. Compared with the contrast material without cerium, the overpotential decreased by 46 mV at 10 mA/cm. Keywords: Electrospinning, CeO2-based composites, oxygen evolution reaction
Pages90
URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/459280
Collection化学化工学院
Affiliation
化学化工学院
First Author AffilicationCollege of Chemistry and Chemical Engineering
Recommended Citation
GB/T 7714
王玮. 氧化铈基复合材料的制备及氧析出反应研究[D]. 兰州. 兰州大学,2021.
Files in This Item:
There are no files associated with this item.
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Altmetrics Score
Google Scholar
Similar articles in Google Scholar
[王玮]'s Articles
Baidu academic
Similar articles in Baidu academic
[王玮]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[王玮]'s Articles
Terms of Use
No data!
Social Bookmark/Share
No comment.
Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.