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Title: | 有機金屬框架薄膜之混合離子電子傳輸之研究 Mixed Ion-Electron Conduction of Thin-Film Metal-Organic Framework |
Other Titles: | Mixed Ion-Electron Conduction of Thin-Film Metal-Organic Framework |
Authors: | 陳咨澔 Tzu Hao Chen |
Advisor: | 陳嘉晉 Chia-Chin Chen |
Keyword: | 有機金屬框架,混合離子電子導體,薄膜, MOF,mixed ion/electron conductor,thin film, |
Publication Year : | 2022 |
Degree: | 碩士 |
Abstract: | 有機金屬框架(Metal organic framework, MOF)是一種由金屬與有機分子互相配位自組裝而形成具有穩定重複結構的材料,MOF透過不同金屬離子與有機分子之間的配位,使其具有高可調節性,高孔洞性、高比表面、均勻孔洞大小的優異性質,使這種材料在催化、吸收、分離等應用上有極佳的表現。然而多數MOF為電子絕緣體,且無法穩定存在於水溶液中,使得其在電化學領域中的應用被大幅縮限。本研究以MOF家族中的UiO-66作為目標材料,其結構乃以鋯(zirconium)為金屬節點,與配位基(ligand)對苯二甲酸(H2BDC)鍵結而成,其獨特性為在水溶液中的高穩定性以及具備質子傳輸導電的能力。但另一方面UiO-66近絕緣的電子傳導限制了其在能源領域的應用。若能理解其傳輸機制,並加以調控材料的電子導電性,將可拓展UiO-66在能源應用的影響性。文獻一般認為UiO-66為質子導體,從本篇實驗結果得知,UiO-66 質子導電度隨著濕度上升增加了三個數量級,證實了其質子導電性質。令人意外的是,UiO-66的電子導電度也會隨著濕度大幅變化,高達四個數量級。在此研究中,我們首度發現UiO-66具備混合離子電子傳導特性,且其傳輸速度能夠透過外在環境調控,這種方式有別於傳統的方法,能更簡易而有效的改變MOF的材料特性。此外,我們量測了材料中的化學擴散係數,以理解材料中的電荷載子的傳輸情形。其中化學擴散係數也與外界濕度成高度相關且高達1x10-7 cm2 s-1。藉由本論文研究成果,我們除了更深入的了解MOF的導電傳輸機制,且成功控制MOF導電特性,未來將能大幅拓展MOF在能源領域的應用。 Metal-organic frameworks (MOFs), are a class of extended solids composed of materials with repeating structures formed by the coordination and self-assembly of metal and organic molecules. The excellent properties of regulation, high porosity, high specific surface, and uniform pore size render this material indispensable in catalysis, absorption, and separation. However, due to the nature of MOF, most of them tend to be electronic insulators, which greatly limits their application in the field of energy storage. In fact, the insulation of MOFs usually arises from the lack of free electrons in metal cations and the redox-inactive ligands in MOF’s structure. UiO-66, as a classical member of MOF, is composed of zirconium as metal nodes which bridge with terephthaltic acid (H2BDC) as ligand. While UiO-66 presents itself as an electron-insulator, it presents the strong advantages as its extraordinary stability in aqueous solutions and the ability to smoothly conduct proton. As a matter of fact, experimental results of our study show that proton conductivity can soar up to three orders of magnitude as the relative humidity of the environment increases. Interestingly, we also found that electron conductivity of UiO-66 varied with relative humidity, and such difference could rise up to four orders of magnitude. As a result, we could reach the conclusion that UiO-66 plays the role as a mixed-conductor, and the transport of the charge carriers in the material is tunable by the condition of external environment, pointing out the simple route to manipulate the material’s properties. In addition, we measured the chemical diffusion coefficient of the material in order to further understand the transport of charge carriers in the material. On that account, we disclosed a high chemical diffusion coefficient 1x10-7 cm2 s-1 for the material, which is subjected to the influence of humidity as well. Consequently, the results of this study allows us to get insight into deeper understanding of the conduction and transport mechanism of MOFs, and eventually, to successfully achieve a keen control of the conduction of MOFs, sparking off the considerable possibilities to apply MOFs in energy field for the foreseeable future. of the application of MOFs energy field will be greatly expanded in the foreseeable future. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/83193 |
DOI: | 10.6342/NTU202204270 |
Fulltext Rights: | 同意授權(限校園內公開) |
Appears in Collections: | 化學工程學系 |
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U0001-1110202212265700.pdf Access limited in NTU ip range | 3.33 MB | Adobe PDF | View/Open |
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