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標題: | 金屬有機骨架於電催化產氧反應之應用 Application of Metal-organic Frameworks for Electrocatalyzing the Oxygen Evolution Reaction |
作者: | Cheng-Hsun Chuang 莊程勛 |
指導教授: | 何國川(Kuo-Chuan Ho) |
關鍵字: | 金屬有機骨架,金屬氧化物,產氧反應,後金屬化,普魯士藍類似物, Metal-organic frameworks,Metal oxides,Oxygen evolution reaction,Post metalation,Prussian blue analogues, |
出版年 : | 2019 |
學位: | 碩士 |
摘要: | 本論文旨在討論金屬有機骨架材料於電催化產氧反應此一能源領域之應用。依照不同的材料此論文被分成兩部分:調節普魯士藍類似物衍生物鈷金屬與鐵金屬於氧化物電催化觸媒之比例於產氧反應之應用(第三章),以及後雙金屬化以鋯與紫質類為基底之金屬有機骨架材料於電催化產氧反應之應用(第四章)。
在第三章中,本研究闡釋出雙金屬普魯士藍類似物可以被當作一個平台來衍生出含不同鈷鐵金屬莫耳比例的鈷鐵金屬氧化物。由於普魯士藍類似物具有含有兩種不同金屬的特性,藉此可以合成出含有均勻分布鈷與鐵金屬的鈷鐵金屬氧化物。此特性使我們能夠探討雙金屬氧化物組成對產氧反應活性的關係。本研究中,我們更進一步說明鐵含量在鈷鐵氧化物中對產氧反應活性的關連性。藉由金屬成分比例的最佳化,適度的鐵含量佔據在鐵鈷氧化物晶格結構中的八面體位址,可以有效地降低電子轉移阻力並提升電催化活性。得益於特殊的結構與化學組成,本研究所合成出的鐵鈷氧化物擁有優異的產氧反應活性,在10 mA cm-2下有310 mV的過電位,並且在鹼性溶液中保有12小時以上良好的操作穩定性。根據實驗結果顯示,我們可藉由普魯士藍類似物衍生物金屬氧化物可調節金屬成分的特性來優化電催化活性,此金屬氧化物具有作為產氧反應之電催化觸媒的潛力。 在第四章中,我們利用以鋯與紫質為基底之金屬有機骨架為一平台去合成金屬有機骨架衍生雙金屬多孔碳材料。由於紫質的中心可以嵌入鐵與鎳金屬,我們首度成功合成出均勻分布紫質中心含鐵與鎳的金屬有機骨架粉末。金屬有機骨架在後金屬化鐵與鎳後具有電催化活性。除此之外,藉由改變進料金屬前驅物的莫耳比例,可以調整金屬有機骨架紫質上鐵與鎳金屬成分的莫耳比例。因此,藉由調整金屬有機骨架中鐵與鎳金屬的莫耳比例,可以得到最佳化的電催化效能。經由碳化過後所得到的鎳鐵碳觸媒不僅能增加導電性,也能增加產氧反應的電催化活性。本研究所合成出的鎳鐵碳化物擁有優異的產氧反應活性,在10 mA cm-2下有310 mV的過電位,並且在鹼性溶液中保有24小時以上良好的操作穩定性。此實驗結果展示了一個有效的策略去製備以金屬有機骨架衍生之雙金屬多孔碳材料電催化產氧反應觸媒。 根據第三章與第四章的核心概念,不同的金屬節點可以連接不同的有機骨架,進而建構出不同種類的有機金屬骨架。由於有機金屬骨架的多樣性,其可以作為一平台來設計以有機金屬骨架為基礎之材料,藉此開發出在能源應用領域中高效率的電催化觸媒。 This thesis aims at the synthesis and characterization of metal-organic frameworks for electrocatalyzing the oxygen evolution reaction in the field of energy application. The thesis is mainly divided into two parts, namely, regulating the cobalt to iron ratio through Prussian blue analogues derived metal oxides as electrocatalysts for oxygen evolution reaction (Chapter 3) and synthesizing bimetallic zirconium-porphyrin-based metal-organic frameworks via post-metalation for oxygen evolution reaction (Chapter 4). In Chapter 3, it is demonstrated that bimetallic Prussian blue analogues (PBA) can be used as a platform to derive Co-Fe oxides with various tunable Co/Fe ratios. Cobalt-iron mixed oxides having homogeneously distributed Co and Fe elements were synthesized to take the advantage of two different metals in the PBA precursors. This characteristic enabled investigation of the composition-activity relationship in bimetal oxides for oxygen evolution reaction (OER). A relationship between the OER activity and Fe content in Co-Fe oxides was further exemplified in this study. By optimizing the composition, the suitable iron contents occupying the octahedral sites in the crystal structure of FeCo oxide can effectively reduce the charge transfer resistance and enhance the electrocatalytic activities. Benefiting from the unique structure and the chemical composition, the as-synthesized FeCo oxide shows an excellent OER activity with a low overpotential of 310 mV at 10 mA cm-2 and a good stability for 12 h operation in alkaline solution. These results suggest that the electrocatalytic activities can be optimized by controllable metal composition of the PBA-derived metal oxides, which are the promising electrocatalysts for OER application. In Chapter 4, zirconium-porphyrin-based metal-organic frameworks (MOF-525) was chosen as a template to synthesize bimetallic MOF-derived porous carbon materials. Since the porphyrin center of tetrakis(4-carboxyphenyl)porphyrin (TCPP) could be metalated with iron and nickel, a powder of MOF constructed by uniform distribution of both Fe(III)TCPP and Ni(II)TCPP was successfully synthesized for the first time. It is found that MOF-525 possesses electrocatalytic properties after being post metalated with Fe and Ni. Furthermore, the proportion of Fe and Ni can be tuned on the porphyrins of MOF-525 by changing the feed molar ratio of the metal precursors. Therefore, an optimized electrocatalytic performance can be achieved by tuning the proportion of Ni and Fe in the MOF-525. After carbonization, the obtained NiFe@C electrocatalysts not only increase the electrical conductivity, but also enhance the OER electrocatalytic activity. The as-synthesized NiFe@C_1_1_2 exhibits the lowest overpotential of 310 mV at 10 mA cm-2 and a good stability for 24 h operation in alkaline solution. This study offers a promising strategy to fabricate the bimetal porous carbon materials derived from MOF-525 as electrocatalysts for OER. Based on the core concept of Chapter 3 and Chapter 4, different metal nodes can connect different organic linkers, and thus construct various kinds of MOFs. Due to the diversity of MOFs, they can serve as a template to design the MOF-based material to developing highly efficient electrocatalysts in the field of energy application. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/73135 |
DOI: | 10.6342/NTU201901327 |
全文授權: | 有償授權 |
顯示於系所單位: | 化學工程學系 |
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