Zeolitic Imidazolate Framework-7로 합성한 ZnO 나노입자의 Acetone 가스 감응 특성

윤지원 ( Ji Won Yoon ),( Rui Wang ),박준식 ( Joon-shik Park ),이종흔 ( Jong-heun Lee ) 한국센서학회 2017 센서학회지 Vol.26 No.3

Highly uniform and well-dispersed Zeolitic Imidazolate Framework-7 (ZIF-7) particles were prepared by the precipitation of Zn²⁺ using benzimidazole, which were converted into ZnO nanoparticles by heat treatment at 500 °C for 24 h. The ZIF-7 derived ZnO nanoparticles showed abundant mesopores, high surface area, and good dispersion. The gas sensing characteristics toward 5 ppm acetone, ethanol, trimethylamine, ammonia, p-xylene, toluene, benzene, and carbon monoxide and carbon dioxide were investigated at 350 - 450℃. ZIF-7 derived ZnO nanoparticles exhibited high response to 5 ppm acetone (R_a/R_g=57.6; R_a: resistance under exposure to the air, R_g: resistance under exposure to the gas) at 450 ℃ and negligible cross-responses to other interference gases (trimethylamine, ammonia, p-xylene, toluene, benzene, carbon monoxide, carbon dioxide) and relatively low responses to ethanol. ZIF derived synthesis of metal oxide nanoparticles can be used to design high performance acetone sensors.

Enhancement of Photocatalytic Activity of Tris (bipyridine) Ruthenium by Encapsulation in Zeolitic Imidazolate Framework-11 and 12

Hyun Sung Kim 한국진공학회(ASCT) 2021 Applied Science and Convergence Technology Vol.30 No.4

In this study, Ru(bpy)₃@ZIF-11 and Ru(bpy)₃@ZIF-12 catalysts (bpy = 2,2′‐bipyridine) were synthesized by encapsulating [Ru(bpy)₃]²⁺ in zeolitic imidazolate frameworks (ZIFs) ZIF-11 and ZIF-12, respectively, and their photocatalytic activities were compared. Samples of different composites were prepared from their powders, and their crystal morphologies and photocatalytic activities were evaluated by X-ray diffraction analysis and UV-visible absorption spectrometry. [Ru(bpy)₃]²⁺@ZIF-12 catalysts possessed excellent photocatalytic stability and exhibited a synergistic effect of [Ru(bpy)₃]²⁺ and Co in the Ru(bpy)₃@ZIF-12 composite, and efficient electron transfer from the [Ru(bpy)₃]²⁺ moiety to the ZIF- 11 framework.

High-flux mixed matrix membranes containing bimetallic zeolitic imidazole framework-8 for C₃H₆/C₃H₈ separation

Oh, Jin Woo,Cho, Kie Yong,Kan, Ming-Yang,Yu, Hyun Jung,Kang, Dun-Yen,Lee, Jong Suk Elsevier 2020 Journal of membrane science Vol.596 No.-

<P><B>Abstract</B></P> <P>Membrane-based gas separation requires highly delicate engineering of molecular structures for the desired separation performance. Herein, a new efficient approach to fabricate high-flux mixed matrix membranes (MMMs) for C<SUB>3</SUB>H<SUB>6</SUB>/C<SUB>3</SUB>H<SUB>8</SUB> separation is reported by utilizing ZnCo-mixed hybrid zeolitic imidazolate framework-8 (ZIF-8-67) with unexpectedly large aperture size. Our structural characterizations in molecular level reveal that the ZIF-8-67 exhibits a larger aperture size compared to ZIF-8. Such a large aperture size of ZIF-8-67 is attributed to the large angle between two neighboring ligands and the long metal-ligand bonding distance, which is confirmed by refining the computed XRD pattern until it matches the experimental one (Rietveld refinement). More importantly, the inclusion of ZIF-8-67 in the 6FDA-DAM matrix enhances the C<SUB>3</SUB>H<SUB>6</SUB> permeability by up to 240% with the moderate C<SUB>3</SUB>H<SUB>6</SUB>/C<SUB>3</SUB>H<SUB>8</SUB> selectivity improvement (70%), as compared to those of the polymeric counterpart. Furthermore, the temperature-dependent transport characterization verifies that the ZIF-containing MMMs improve the C<SUB>3</SUB>H<SUB>6</SUB>/C<SUB>3</SUB>H<SUB>8</SUB> energetic selectivity at the sacrifice of entropic selectivity due to a unique molecular sieving behavior of the ZIFs, thereby enhancing the diffusivity selectivity. This study proposes a simple strategy to enable the fine-tuning of the aperture size of parent ZIFs towards the desired gas separation performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The effect of mixed metals of ZIFs on structure and transport properties was studied. </LI> <LI> Bimetallic ZnCo metal-mixed ZIF-8 (ZIF-8-67) exhibited an unexpected aperture size. </LI> <LI> ZIF-8-67-containing MMMs significantly enhanced C<SUB>3</SUB>H<SUB>6</SUB> permeability. </LI> <LI> ZIF-containing MMMs improved C<SUB>3</SUB>H<SUB>6</SUB>/C<SUB>3</SUB>H<SUB>8</SUB> energetic selectivity due to breathable behavior. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Vanadium Redox Flow Battery Using Electrocatalyst Decorated with Nitrogen-Doped Carbon Nanotubes Derived from Metal-Organic Frameworks

Noh, Chanho,Lee, Chang Soo,Chi, Won Seok,Chung, Yongjin,Kim, Jong Hak,Kwon, Yongchai The Electrochemical Society 2018 Journal of the Electrochemical Society Vol.165 No.7

<P>Highly porous zeolitic-imidazole frameworks (ZIFs) are synthesized to produce N-doped mesoporous carbon electrocatalysts via calcination. The N-doped carbon (m-NC) and carbon nanotubes (m-NCNT) are obtained from ZIF-8 and ZIF-67, while the core-shell structure of ZIF-8@ZIF-67 produced with ZIF-8 seeds (m-NC@NCNT) is prepared by hydrothermal method. Chemical and optical evaluations of the catalysts are characterized using BET, FT-IR, XPS, XRD, Raman spectroscopy and SEM/STEM and they are used as the catalysts for redox reactions of vanadium ions and redox flow battery (VRFB) performance. In the utilization, m-NC@NCNT and m-NCNT are effective for improving VO2+/VO2+ redox reaction, although m-NC does not influence that. Even in VRFB tests using the catalysts, charge/discharge potential and energy efficiency (EE) of m-NC@NCNT and m-NCNT are highest, not to mention excellent EE resilience after undergoing tougher cycling condition. These results are due to the large graphitic-N portion of the two catalysts. Namely, electrons produced by the graphitic-N are delocalized, forming pi-conjugated system and vanadium-nitrogen transition state. This state then promotes electron transfer during VO2+/VO2+ redox reaction and VRFB performance. (C) 2018 The Electrochemical Society.</P>

Systematic Narrowing of ZIF-8 Apertures via Controlled 2-Ethylimidazole Doping for Hydrogen/Carbon Dioxide Separation

Yang Lee,Park Sunghwan,Han Wong Zhong,Razak Musab Abdul,Zhen Lee Yong,Faires Muhammed,Omar Rozita,Choong Thomas Shean Yeaw,Rohani Rosiah,Hamid Mohamad Rezi Abdul 한국화학공학회 2024 Korean Journal of Chemical Engineering Vol.41 No.8

Sodalite (SOD) zeolitic-imidazolate frameworks (ZIFs) with uniform angstrom scale apertures can off er high gas sieving ability for separation applications. Fixed apertures of ZIFs can eff ectively separate specifi c gas pair but may not be able to provide similar level of separation for larger or smaller gas pairs. Multivariate (i.e., mixed-linker) ZIFs with controlled linker incorporation can provide desired aperture tuning but diffi cult to synthesize especially when incorporating linkers that would normally form diff erent structures. Herein, we report a systematic narrowing of SOD ZIF-8 by partially replacing 2-methylimidazole (mIm) linkers of ZIF-8 with 2-ethylimidazole (eIm) via delayed linker addition (DLA) method. Percentages of eIm in the hybrid frameworks were determined to be around 14.3%, 9.1%, and 5.1% for ZIF-8 nuclei formed in 5, 12.5, and 20 min, respectively. Ethyl moiety of eIm restricts framework fl exibility of the hybrid ZIF-8, shifts ZIF-8 gate-opening pressure to higher value, and eventually diminishes the gate-opening eff ect. Polysulfone (PSF)-based mixed-matrix membranes utilizing eIm-doped ZIF-8 as fi llers displayed slight reduction in CO 2 permeability (18.56 Barrer to 14.85 Barrer) which result in H 2 /CO 2 ideal selectivity improvement. DLA method is expected to work well for other imidazole-based linkers and can perhaps be used to synthesize mixed-linker of other SOD ZIFs.

Synthesis and performance evaluation of zeolitic imidazolate framework-8 membranes deposited onto alumina hollow fiber for desalination

Nizar Mu’ammar Mahpoz,Norfazliana Abdullah,Mohamad Zahir Mohd Pauzi,Mukhlis A. Rahman,Khairul Hamimah Abas,Azian Abd Aziz,Mohd Hafiz Dzarfan Othman,Juhana Jaafar,Ahmad Fauzi Ismail 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.3

This work describes the development of zeolitic imidazolate framework-8 (ZIF-8) membranes on modified alumina hollow fiber for desalination by forward osmosis. Effects of different seeds (ZnO, NiO and PDA) and sodium formate on in-situ deposition of ZIF-8 were studied in relation to the membrane’s morphology and performance. XRD result shows that ZIF-8 was successfully synthesized in the presence of sodium formate. FESEM images showed PDA modified support was unsuccessful in producing well defined and dense ZIF-8 membrane layer even after another ZIF-8 re-deposition due to its minimal amount. The NiO modified support was also found unsuccessful, as ZIF-8 crystals were formed in clusters. On the contrary, dense ZIF-8 membrane was successfully prepared on ZnO modified support with SF-1 synthesis solution producing bigger ZIF-8 crystal and thinner ZIF-8 membrane than as of SF-2. Water flux performance in forward osmosis showed that NiO/ZIF-8, PDA/ZIF-8 and PDA/ZIF-8 (re-deposition) membranes gave negative water fluxes of 50 kg/m2·h, 5.2 kg/m2·h and 1.7 kg/m2·h with reverse solutes of 42.66 mol/m2·h, 27.42mol/m2·h and 3.22 mol/m2·h, respectively, indicating the solute from draw solution diffused into the feed solution. However, ZIF-8 membrane prepared using SF with molar ratio of 1, on the ZnO modified support had a water flux of 13.3 kg/m2·h, reverse solute of 0.95 kg/m2·h and salt rejection of 52.1%. When the SF ratio was increased to 2, the ZIF-8 membranes showed a water flux of 12.5 kg/m2·h, reverse solute of 1.64 kg/m2·h and salt rejection of 54.9%. The moderate salt rejection could be associated with defects in the ZIF-8 membranes due to poor grain boundaries.

물을 사용한 ZIF-8/폴리우레탄 멤브레인의 제조

이예찬(Ye-Chan Lee),정윤경(Yun-Gyeong Jeong),이연식(Youn-Sik Lee) 한국고분자학회 2022 폴리머 Vol.46 No.6

최근에 금속-유기 구조체(MOF)의 응용범위 확대와 가공성 향상을 위하여 MOF/고분자 하이브리드 멤브레인에 대한 연구들이 활발하게 진행되고 있는데, 멤브레인들은 일반적으로 고분자 용액과 MOF 입자로부터 제조된다. 본 연구에서는 MOF의 일종인 zeolitic imidazolate framework-8(ZIF-8)를 선택하여 유기용매를 사용하지 않는 방법으로 ZIF-8/고분자 하이브리드 멤브레인을 제조하고자 하였다. 먼저 ZIF-8 나노입자의 분산성을 향상시키기 위하여 Zn<SUP>2+</SUP>, 2-methylimidazole 및 술폰산화 폴리스티렌(PSS) 수용액으로부터 PSS@ZIF-8 나노입자를 합성한 후, 분산제와 함께 폴리우레탄(PU) 에멀젼에 분산시키고 폴리스티렌 기판 위에 캐스팅함으로써, 투명한 ZIF-8/PU 멤브레인을 성공적으로 제조하였으며 멤브레인의 인장특성과 함수율을 고찰하였다(PSS@ZIF-8 함량: 최대 41 wt%). In order to extend application field and improve processability of crystalline metal-organic frameworks (MOFs), recently MOF/polymer hybrid membranes have been actively studied. Such membranes are generally prepared from polymer solutions and MOF particles. In this research, we chose zeolitic imidazolate framework-8 (ZIF-8), one of MOF families, and attempted to prepare ZIF-8/polymer hybrid membranes without using any organic solvent. In order to improve dispersibility of ZIF-8 particles, ZIF-8 was prepared from an aqueous solution containing Zn<SUP>2+</SUP>, 2-methylimidazole and polystyrene sulfonate (PSS). Through dispersion of PSS@ZIF-8 particles along with a dispersing agent into a polyurethane (PU) emulsion and casting on a polystyrene substrate, transparent ZIF-8/PU membranes were successfully prepared (PSS@ZIF-8 content: maximum 41 wt%), and characterized with respect to their tensile properties and water uptakes.

Synthesis of metal-organic frameworks: A mini review

안화승,Yu-Ri Lee,Jun Kim 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.9

Metal organic frameworks (MOFs) are porous crystalline materials of one-, two-, or three-dimensional networks constructed from metal ions/clusters and multidentate organic linkers via coordination bonding, which are emerging as an important group of materials for energy storage, CO2 adsorption, alkane/alkene separation, and catalysis. To introduce newcomers in chemical engineering discipline to the rapidly expanding MOF research works, this review presents a brief introduction to the currently available MOFs synthesis methods. Starting from the conventional solvothermal/hydrothermal synthesis, microwave-assisted, sonochemical, electrochemical, mechanochemical, ionothermal, drygel conversion, and microfluidic synthesis methods will be presented. Examples will be limited to those representative MOF structures that can be synthesized using common organic ligands of 1,4-benzenedicarboxylic acid (and its functionalized forms) and 1,3,5-benzenetricarboxylic acid, in conjunction with metal nodes of Zn2+, Cu2+, Cr3+, Al3+,Fe3+ and Zr4+. Synthesis of widely-investigated zeolitic imidazolate framework (ZIF) structure, ZIF-8 is also included.

Tuning crystalline structure of zeolitic metal–organic frameworks by supersonic spraying of precursor nanoparticle suspensions

Joshi, Bhavana N.,Lee, Jong-Gun,An, Seongpil,Kim, Do-Yeon,Lee, Ji Sun,Hwang, Young Kyu,Chang, Jong-San,Al-Deyab, Salem S.,Tan, Jin-Chong,Yoon, Sam S. Elsevier 2017 Materials & Design Vol.114 No.-

<P><B>Abstract</B></P> <P>The deposition of sodalite zeolitic imidazolate framework-7 (ZIF7) films by a supersonic cold-spraying technique was successfully accomplished for the first time. The high-speed impact of supersonic cold spraying increased the monodispersity of the ZIF7 crystalline structure. However, the intensity of the structural change decreased with increasing the amount of nylon in the ZIF7 suspension. Mitigating phase changes in ZIF7 occurred by the impact dampening conferred by the polymeric nature of nylon, which preserved the original three-dimensional crystalline structure of ZIF7. The inclusion of <I>N</I>,<I>N</I>-dimethylformamide (DMF) in a nylon–ZIF7 suspension improved the dispersion of ZIF7 nanoparticles, which in turn eliminated the dampening effect from the nylon and recovered the distinctive monodispersity arising from the high-speed impact. This characteristic was observed at all impact speeds for ZIF7 suspensions containing DMF. We show that high-rate cold spraying of ZIF7 particles can be combined with nylon and other pressure-transmitting media to control the formation of three distinctive phases. The unique capability to tune the crystalline structure of ZIF7 allows customization of the film functionality for specific applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Zeolitic Imidazolate Framework-7 (ZIF7) films have been fabricated by a supersonic cold-spraying method. </LI> <LI> Crystalline structures of the supersonically sprayed ZIF7 film can be controlled by adjusting the nylon content. </LI> <LI> Supersonic spraying technique is versatile, it can be used to fabricate ZIF7 phase-I, -II, and -III. </LI> <LI> Inclusion of 6 wt% of nylon improves framework mechanical stability, preventing phase changes upon high-energy impact. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Particle size distribution change of zeolitic imidazolate framework-67 according to cobalt ion and ligand addition and their electrochemical characterization as lithium-sulfur cells cathode

박준형,김석 한국공업화학회 2023 한국공업화학회 연구논문 초록집 Vol.2023 No.0