• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4199-4204
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• 2011

Using models simulating the environment of two distinct adsorption sites of $H_2$ in metal-organic framework-5 (MOF-5), binding energies of $H_2$ to MOF-5 were evaluated at the MP2 and CCSD(T) level. For organic linker section modeled as dilithium 1,4-benzenedicarboxylate ($C_6H_4(COO)_2Li_2$), the MP2 and CCSD(T) basis set limit binding energies are estimated to be 5.1 and 4.4 kJ/mol, respectively. For metal oxide cluster section modeled as $Zn_4O(CO_2H)_6$, while the MP2 basis set limit binding energy estimate amounts to 5.4 kJ/mol, CCSD(T) correction to the MP2 results is shown to be insignificant with basis sets of small size. Substitution of benzene ring with pyrazine ring in the model for the organic linker section in MOF-5 is shown to decrease the $H_2$ binding energy noticeably at both the MP2 and CCSD(T) level, in contrast to the previous study based on DFT calculation results which manifested substantial increase of $H_2$ binding energies upon substitution of benzene ring with pyrazine ring in the similar model.

• Journal of the Korean Applied Science and Technology
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• v.37 no.2
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• pp.260-267
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• 2020

In this study, supercapacitor based on the all solid state electrolyte with PVA(polyvinyl alcohol), ionic liquid as a BMIMBF4(1-buthyl-3-methylimidazolium tetrafluoroborate) and activated carbon/Ni-MOF composite was fabricated and characterized its electrochemical properties with function of MOF. In order to analysis and comparison that electrochemical performances [including cyclic voltammetry(CV), electrochemical impedance spectroscopy(EIS) and galvanostatic charge/discharge test] of prepared supercapacitor based on activated carbon/Ni-MOF composite and all solid state electrolyte. As a result, specific capacitance of the supercapacitor without Ni-MOF was 380 F/g which value decreased to 340 F/g after adding Ni-MOF to activated carbon as a electrode material. This result exhibited that decreased electrochemical property of the supercapacitor effected on physical hinderance in the electrode. In further, it needs to optimization of the Ni-MOF amount (wt%) in the electrode composite to maximize its electrochemical performances.

• Korean Journal of Optics and Photonics
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• v.29 no.6
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• pp.268-274
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• 2018

In this study we suggest a humidity-sensitive color sensor using a one-dimensional photonic crystal and Hong Kong University of Science and Technology-1 (HKUST-1), which is a metal-organic framework (MOF) substance. One-dimensional photonic crystals have a photonic band gap, due to a periodic refractive-index change, and block and reflect light components in a specific wavelength band. The refractive index of HKUST-1 differs in dry and humid environments. Herein we designed a sensor using the presence of the photonic band gap, with FDTD simulation. As a result of optical analysis, the color conversion of the reflected light was superior to the color conversion of the transmitted light. When the center wavelength of the photonic band gap was 550 nm, the maximum peak value of the wet environment increased by a factor of about 9.5 compared to the dry environment, and the color conversion from achromatic to green was excellent as a sensor. The results of this study suggest the application of MOF materials to moisture sensors, and the nanostructure design of MOF materials will expand the applications to industrial devices.

• Clean Technology
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• v.29 no.1
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• pp.71-75
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• 2023

In general, the presence of non-selective intercrystalline (grain boundary) defects in polycrystalline metal-organic framework (MOF) or zeolite membranes, which are known to be ca. 1 nm in size, causes lower membrane performance (selectivity) than the intrinsically expected. In this study we show that applying a thin polymeric coating of polydimethylsiloxane (PDMS) on a polycrystalline MOF membrane is effective to cap the non-selective intercrystalline defects and therefore improve membrane performance. To demonstrate the concept, first, polycrystalline UiO-66, one of Zr-based MOFs, membranes were prepared by an in-situ solvothermal growth. By controlling membrane growth condition with respect to growth temperature, we were able to obtain polycrystalline UiO-66 membranes at 150 ℃ with intercrystalline defects of which the quantity is not significant, so it can be plugged by the suggested PDMS deposition. Second, their performances were compared before and after the PDMS deposition. As expected, the PDMS deposition ended up with a noticeable increase in CO₂/N₂ ideal selectivity from 6 to 14, indicating successful intercrystalline defect plugging. However, the enhancement in CO₂/N₂ selectivity was accompanied by a significant reduction in CO₂ permeance from 5700 to 33 GPU because the PDMS deposition not only plugs defects but also forms a continuous coating on membrane surface, adding an additional transport resistance.

• 한국전기화학회:학술대회논문집
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• 2004.06a
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• pp.287-292
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• 2004

In order to understand the relationship between molecular structure of Metal-Organic Framework(MOF) and capacity of hydrogen absorption, quantum mechanical calculations and grand canonical Monte Carlo simulations have been carried out on a series of MOF-5 having various organic linkers. The calculation results about specific surface area and electron density for various frameworks indicated that the capacity of the hydrogen storage is largely dependent on effective surface area rather than the free volume. Based on the iso-electrostatic potential surface from density functional calculation and the amount of adsorbed hydrogens from grand canonical Monte Carlo calculation, it was also found that the electron localization ground organic linker plays an important role in hydrogen capacity of MOFs.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.3111-3114
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• 2012

• Bulletin of the Korean Chemical Society
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• v.31 no.1
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• pp.220-223
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• 2010

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.301-304
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• 2014

• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1583-1585
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• 2013

• Journal of the Korean Ceramic Society
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• v.53 no.2
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• pp.200-205
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• 2016

With high specific surface area and pore structural diversity, MOFs show important applications in gas storage, catalysis, sensing, separation, and biomedicine. However, the stability of the structure of MOFs has restricted their application and development. In this study, zirconium metal organic frameworks with 9,10-dicarboxylic acid anthracene as ligand, named UIO-66 ($H_2DCA$), were synthesized and their properties and structures were characterized by XRD, SEM, and $N_2$ adsorption. We focus on the stability of the structure of UIO-66 ($H_2DCA$) under different conditions (acid, alkali, and water). The structural changes or ruins of UIO-66 ($H_2DCA$) were traced by means of XRD, TG, and FT-IR under different conditions. The results show that the UIO-66 ($H_2DCA$) materials are stable at 583 K, and that this structural stability is greatly influenced by different types of acid and alkali compounds. Importantly, we found that the structures maintain their stability in environments of nitric acid, triethylamine, and boiling water.