兰州大学机构库 >化学化工学院
基于稀土铈调控的过渡金属电催化剂合成及其电解水应用研究
Alternative TitleSynthesis of Transition Metal Electrocatalysts Regulated by Rare Earth Cerium and Application in Water Electrolysis
安海燕
Subtype博士
Thesis Advisor唐瑜
2023-05-30
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name理学博士
Degree Discipline化学
Keyword稀土铈 Rare earth cerium 配位聚合物 coordination polymer 异质结构 heterostructure 电催化 electrocatalysis
Abstract

       稀土基功能化材料在发光、磁性和催化等领域有着广泛的应用。尤其近年来稀土基功能材料已被广泛应用于电催化研究。过渡金属基电催化材料具有良好的电催化性能,但是催化活性和稳定性还不能满足当下能源的需求。铈离子掺杂或二氧化铈复合过渡金属电催化材料中,有助于提高过渡金属的电子转移,优化中间体和活性位点的结合能,促进中间体的吸附和转化,可显著提升催化剂的电催化活性。因此,合理地设计稀土基功能材料,对开发新型高效且具有成本效益的稀土基功能电催化剂具有重要意义。
       目前报道的具有电催化性能的稀土基功能材料主要以无机材料为主,因此,如何拓展稀土基功能电催化材料成为该领域的重点。本文基于铈离子对羧酸配体具有高的亲和力,配位数高,配位方式多样,过渡金属离子倾向于与氮原子配位的特点,发展了铈与过渡金属离子之间的“协同配位作用”构建和调控形貌及结构,获得了铈基新型配位杂化和独特异质结结构的电催化材料,展现出显著提升的电催化性能。本文的研究重点如下:
       1. 通常情况下配位聚合物材料在电化学氧化性环境下容易被氧化为金属氧化物/氢氧化物,以及骨架结构易发生坍塌。由于吡啶羧酸类配体表现出对金属离子高的选择配位性,尤其是芳香类吡啶羧酸配体与金属具有较强的配位能力。因此,该工作采用溶剂热法,利用含氧和氮原子多个配位点的2,3-吡啶二甲酸配体与铈和过渡金属原子配位,通过不同性质的金属离子与同一配体之间的“协同配位”获得了形貌为球形的稀土基铈异金属配位聚合物。其中,由于不同金属性质
的差异,铈和过渡金属镍或钴与配体配位获得中空纳米球,引入过渡金属铁,获得实心纳米球配位聚合物。由于铈基异金属配位聚合物结构内存在芳香环,结构在一定程度上具有共轭性,有利于结构内电子和和能量传递,以及稀土离子与羧基基团上的氧原子会产生较强的键合作用,有利于框架结构的稳定性,因此,制备的铈基异金属配位聚合物表现出良好的OER催化活性和稳定性。
       2. 鉴于二维材料通常表现出区别于体相材料的优势,以及稀土基无机有机杂化材料结合无机稀土和有机组分的优势。因此,如何合成超薄CeO2基无机有机杂化电催化材料仍是一个需要解决的问题。该工作以油酸稳定的超薄CeO2纳米片为前体,使用配体交换的方法合成得到对苯二甲酸配位在超薄CeO2纳米片表面的无机有机杂化材料,通过超薄CeO2纳米片表面配位的对苯二甲酸末端羧基锚定过渡金属离子,获得超薄CeO2基无机有机杂化异质结构(CeO2@NiFe-
MOFs),其中单层NiFe-MOFs配位在超薄CeO2纳米片表面上下表面。由于在超薄CeO2纳米片表面重新配位并锚定了过渡金属离子,CeO2表现出的电子、光学、带隙和表面局部应变与油酸稳定的超薄 CeO2相比有着明显的不同,证明了基于配位作用构建的超薄二维异质结构中金属配位的相互作用性。由于单层NiFe-MOFs表面的金属活性位点更多的被暴露出来,有利于电解液充分接触,对苯二甲酸的共轭性有效稳定结构,促进电子在NiOOH活性物质与CeO2之间转移,因此,超薄CeO2@NiFe-MOFs无机有机杂化异质结构显示出良好的OER催化活性和结构稳定性。
       3. 通过热分解配位聚合物可以获得各种保持配位聚合物形貌的功能纳米材料。该工作中,选取含氧和氮的螯合型有机配体,通过调控反应条件,利用协同配位机制将稀土离子(Ce3+)和过渡金属镍离子(Ni2+)引入至同一骨架中构建新型特定形貌稀土基异金属配位聚合物(NiCe-CPs)。反应体系中碱的浓度对稀土基异金属配位聚合物特定形貌起着重要的作用,在非常低的碱浓度条件下合成获得花状结构配位聚合物,而在相对较高碱浓度下得到纳米球状配位聚合物。其中合成特定形貌(花状结构)稀土基异金属配位聚合物材料的方法对稀土元素具有一定的普适性。通过热分解NiCe-CPs 获得结晶/非晶态(a-NiO/c-NiCeOx)特定结构功能纳米材料。高分辨透射电镜表征证明了在a-NiO/c-NiCeOx结构中存在晶态相(c-NiCeOx)和非晶态相 NiO;拉曼光谱也证明在产物结构表面具有大量的非晶态NiO。a-NiO/c-NiCeOx表现出达到OER电流密度10 mA cm-2时,仅需要过电位240 mV。DFT方法证明了在a-NiO/c-NiCeOx异质结构中非晶态NiO可以显著提高电荷转移效率,降低反应能垒,从而提升催化性能。

Other Abstract

     Rare earth-based functionalized materials have promising potential application in the fields of luminescence, magnetism, and catalysis. Especially, rare earth-based functional materials have been widely used in electrocatalysis field in the past few years. Transition metal-based electrocatalytic materials exhibit good electrocatalytic performance, whereas the catalytic activity and stability cannot meet the current energy demand. When the transition metal electrocatalytic materials doped or composited by cerium, the cerium could improve the electron transfer of transition metals, optimize the binding energy of intermediates and active sites, promote the adsorption and
conversion of intermediates, and significantly improve the catalytic activity. Therefore, it is of great significance to rationally design rare earth-based functional materials to
develop new efficient and cost-effective rare earth-based functional electrocatalysts.
     The reported the rare earth-based functional materials with electrocatalytic properties are mainly inorganic materials. Therefore, how to expand rare earth-based functional electrocatalytic materials has become the focus of this field. In this work, based on the characteristics that rare earth cerium ions have high affinity for carboxylic acid ligands, high coordination numbers, and various coordination modes, while
transition metal ions tend to coordinate with nitrogen atoms, the "synergistic coordination of rare earth cerium and transition metal ions" was developed to construct and regulate structure and morphology, and obtain a rare earth cerium-based electrocatalytic material with a new type of coordination hybrid and a unique heterostructure, exhibiting obviously improved performance. The works are as follows:
     1. Generally, coordination polymer materials are easily oxidized to metal oxides/hydroxides in an electrochemical oxidative environment, and the skeleton structure is prone to collapse. Pyridine carboxylic acid ligands show high selective
coordination to metal ions, especially, aromatic pyridine carboxylic acid ligands produce strong coordination ability with metals. Therefore, in the work, the 2,3-pyridine dicarboxylic acid ligands with multiple coordination sites of containing
oxygen and nitrogen atoms was used to coordinate with rare earth cerium and transition metal atoms through the "synergistic coordination" under solvothermal reaction, and
obtain the rare earth cerium-heterometallic coordination polymer with a spherical shape. Due to the difference in properties for different metals, rare earth cerium and transition
metal nickel or cobalt are coordinated with ligands to obtain hollow nanospheres, while transition metal iron is introduced, resulting in the production of solid nanosphere coordination polymers. Due to the presence of aromatic rings in the structure of the cerium-based heterometallic coordination polymer, and the aromatic structure is beneficial to the electron and energy transfer, and the rare earth ion and the oxygen
atom on the carboxyl group will produce a strong bonding effect, the combination of these factors together is conducive to the stability of the framework structure. Therefore, the prepared cerium-based heterometallic complex polymers exhibit good catalytic activity and stability.
     2. Given the fact that two-dimensional materials usually exhibit advantages that are different from bulk materials, and rare earth-based inorganic-organic hybrid materials combine the advantages of inorganic rare earth and organic components. Therefore, how to synthesize ultrathin CeO2-based inorganic-organic hybrid electrocatalytic materials is still a problem to be solved. In the work, oleic acid-stabilized ultrathin CeO2 nanosheets were used as precursors to synthesize inorganic-organic hybrid materials with terephthalic acid coordinated on the surface of ultrathin CeO2 nanosheets by ligand exchange. Surface-coordinated terephthalic acid terminal carboxyl groups anchor transition metal ions to obtain ultrathin CeO2-based inorganic-organic hybrid heterostructures (CeO2@NiFe-MOFs), in which monolayer NiFe-MOFs are coordinated to both the top and bottom surface of CeO2 nanosheets via joining carboxylic acid groups. Compared with oleic acid-stabilized ultrathin CeO2, CeO2 nanosheets decorated with NiFe-MOFs present different electronic, optical properties, bandgap, as well as local strain due to the re-coordination and anchoring of transition metal ions on its surface, demonstrating the coordinative binding interactions in the ultrathin two-dimensional heterostructures constructed based on coordination. Since the monolayer NiFe-MOFs expose more active sites on the surface, which is conducive to the contact with the electrolyte, and the conjugation of terephthalic acid effectively stabilizes the structure and promotes the electron transfer between the NiOOH active material and CeO2. Therefore, the ultrathin CeO2@NiFe-MOFs inorganic-organic hybrid heterostructure exhibits enhanced OER catalytic activity and structural stability.
     3. The various functional nanomaterials can be obtained by the thermal decomposition of coordination polymers. In the work, the chelating organic ligands containing oxygen and nitrogen was selected, and by adjusting the reaction conditions, rare earth ions (Ce3+) and transition metal nickel ions (Ni2+) were introduced into the same framework to construct rare earth-based heterometallic coordination polymers with specific morphology (NiCe-CPs). The concentration of alkali in the reaction system plays an important role for the formation of specific morphology, the
coordination polymer with flower-like structure was synthesized under the condition of very low alkali concentration, while at relatively high alkali concentration, a nano-spherical coordination polymer is obtained. The method has also been found to be universal for synthesizing other rare earth-based heterometallic coordination polymers with flower-like structure. Crystalline/amorphous (a-NiO/c-NiCeOx) functional nanomaterials were obtained by thermal decomposition of NiCe-CPs. High-resolution transmission electron microscope characterization proves that there are crystalline phase (c-NiCeOx) and amorphous phase NiO in the a-NiO/c-NiCeOx structure; Raman spectroscopy also proves that there are more amorphous NiO on the surface of the structure. a-NiO/c-NiCeOx exhibited an overpotential of 240 mV at current density of 10 mA cm-2 . The DFT method demonstrated that amorphous NiO in the a-NiO/c-NiCeOx heterostructure can significantly improve the charge transfer efficiency and lower the reaction energy barrier, thereby enhancing the catalytic performance.

Subject Area稀土纳米材料
MOST Discipline Catalogue理学 - 化学 - 无机化学
URL查看原文
Language中文
Other Code262010_120190902840
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/536837
Collection化学化工学院
Affiliation
兰州大学化学化工学院
Recommended Citation
GB/T 7714
安海燕. 基于稀土铈调控的过渡金属电催化剂合成及其电解水应用研究[D]. 兰州. 兰州大学,2023.
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
[安海燕]'s Articles
Baidu academic
Similar articles in Baidu academic
[安海燕]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[安海燕]'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.