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Synthesis, Gas Adsorption and Proton Conduction of Metal-organic Frameworks 원문보기

  • 저자

    Phang, Won Ju

  • 학위수여기관

    고려대학교 대학원

  • 학위구분

    국내박사

  • 학과

    화학과

  • 지도교수

    홍창섭

  • 발행년도

    2014

  • 총페이지

    167p

  • 키워드

    MOF;

  • 언어

    eng

  • 원문 URL

    http://www.riss.kr/link?id=T13541934&outLink=K  

  • 초록

    The work herein describes the synthesis, gas adsorption, and proton conduction of metal-organic frameworks (MOFs). The research focused on synthesizing new MOFs exhibiting selective CO2 adsorption property, and on developing the proton conducting MOFs. In chapter 1, some of well-known properties of MOFs are introduced briefly. Especially, selective CO2 adsorption and proton conduction in MOFs will be demonstrated in depth. In chapter 2, we will show that the syntheses and crystal structures of a 3-dimensional (3-D) coordination network [Zn4(2-mBIM)5(C2H6NCOO)(HCOO)(μ-OH)]•DMF (1•DMF; 2-mBIM = 2-methylbenzimidazolate) and a 2-dimensional (2-D) layer [Zn2(2-mBIM)3(HCOO)(H2O)]•DMF (2•DMF). Different structures were produced depending on the ratio of reactants. Structurally, 1 illustrates the formation of a unique framework based on a 2-mBIM bridge with the side group on an imidazole ring, while 2 possesses a honeycomb layer built up purely from imidazolates. For gas sorption, CO2 was adsorbed on the activated phase of 1 but N2 was not taken up. In chapter 3, a 2-D Zn(II) metal–organic framework with flexible aryl ether linkers and water molecules exposed to the pores was investigated. The supramolecular 3D network is generated by the presence of extensive π–π contacts, which could be responsible for gas uptake. The water molecules and oxygen atoms from the flexible linkers create a polar environment within the integrated framework, leading to simultaneous selective CO2 adsorption and proton conductivity in the 2-D Zn(II) framework. In chapter 4, a porous metal-organic framework (MOF) [Ni2(dobdc)(H2O)2]•6H2O (Ni2(dobdc) or Ni-MOF-74; dobdc4– = 2,5-dioxido-1,4-benzenedicarboxylate) with hexagonal channels, was synthesized using a microwave-assisted solvothermal reaction. Soaking Ni2(dobdc) in sulfuric acid solutions at different pH values afforded new proton-conducting frameworks, H+@Ni2(dobdc). At pH = 1.8, the acidified MOF yields a proton conductivity of 2.2 x 10-2 S/cm at 80 oC and 95% relative humidity (RH), which is commensurate with the highest values reported for MOFs. Proton conduction occurs via the Grotthuss mechanism with significantly low activation energy among the proton-conducting MOFs. Protonated water clusters within the pores of H+@Ni2(dobdc) play an important role in the conduction process. In chapter 5, we will exhibit the proton conductivity of sulfonic acid functionalized UiO-66 (UiO-66(SO3H)2) which was obtained by post-synthetic modification (PSM) method. This material shows high thermal and water stability. Its proton conductivity reveals 8.4 x 10-2 S/cm at 80 oC, 90% RH (relative humidity) which is the record for MOFs measured under similar conditions.


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