The complexation of silicon with carbon materials is considered an effective method for using silicon as an anode material for lithium-ion batteries. In the present study, carbon frameworks with a 3D porous structure were fabricated using metal–organic frameworks (MOFs), which have been drawing significant attention as a promising material in a wide range of applications. Subsequently, the fabricated carbon frameworks were subjected to CVD to obtain silicon-carbon complexes. These siliconcarbon complexes with a 3D porous structure exhibited excellent rate capability because they provided sufficient paths for Li-ion diffusion while facilitating contact with the electrolyte. In addition, unoccupied space within the silicon complex, combined with the stable structure of the carbon framework, allowed the volume expansion of silicon and the resultant stress to be more effectively accommodated, thereby reducing electrode expansion. The major findings of the present study demonstrate the applicability of MOF-based carbon frameworks as a material for silicon complex anodes.

Selenium (Se), a vital trace element found naturally, plays a pivotal role for human being in low concentrations. Notably, within the spectrum of essential elements, Se possesses the most restricted range between the dietary deficiency (< 40 μg day-1) and the acute toxicity (> 400 μg day-1). Therefore, it is of paramount importance to maintain bioavailable Se levels within permissible limits in our drinking water sources. Among the various Se species, inorganic variants such as selenite (SeO3 2-) and selenate (SeO4 2-) are highly water-soluble, with SeO3 2- being notably more toxic than SeO4 2-. Consequently, the primary focus lies in effectively sequestering SeO3 2- from aquatic environments. Numerous methods have been investigated for SeO3 2- adsorption, including the use of metal oxides and carbon-based materials. Especially, iron oxides have garnered extensive attention due to their water stability and environmentally friendly properties. Nevertheless, their limited surface area and insufficient adsorption sites impose constraints on their efficacy as materials for SeO3 2- removal. Recently, metal–organic frameworks (MOFs), composed of metal centers bridged by organic linkers have increasingly focused as promising adsorbents for SeO3 2- removal, offering significant advantages such as large surface areas, high porosities, and structural versatility. Furthermore, there is a growing interest in defective MOFs, where intentional defects are introduced into the MOF structure. This deliberate introduction of defects aims to enhance the adsorption capacity by increasing the number of available adsorption sites. In this context, herein, we present the Fe-BTC (BTC = 1,3,5-benzenetricarboxylic acid) synthesized via a post-synthetic metal-ion metathesis (PSMM) approach, which is one of the defect engineering methods applied to metal sites. We employ the well-established MOF, HKUST-1, known for its substantial surface area, as the pristine MOF. While the pristine MOF has a crystalline phase, during the PSMM process, Fe-BTC is transformed into an amorphous phase by allowing the introduction of numerous metal defect sites. These introduced metal defect sites serve as Lewis acidic sites, enhancing the adsorption capability for selenite. Furthermore, despite its amorphous nature, Fe-BTC exhibits a substantial surface area and porosity comparable to that of the crystalline pristine MOF. Consequently, Fe-BTC, distinguished by its numerous adsorption sites and its high porosity, demonstrates a remarkable capacity for selenite adsorption.

Owing to the rapid rise of global energy demands, the operation of nuclear power plants is still indispensable. However, following the nuclear accident at Fukushima-Daiichi in 2011, the secure sequestration of radioactive waste has become critical for ensuring safe operations. Among various forms of nuclear wastes, capturing radioactive organic iodide (ROIs, e.g., methyl iodide, ethyl iodide, and propyl iodide) as one of the important species in gas phase waste has been challenged owing to the insufficient sorbent materials. The environmental release of ROIs with high volatility can give rise to adverse effects, including the accumulation of these substances in the thyroid and the development of conditions such as hypothyroidism and thyroid cancer. Compared to an iodine molecule, ROIs exhibit low affinity for conventional sorbents such as Ag@mordenite zeolite and triethylenediamine-impregnated activated carbon (TED@AC), resulting in lower sorption rates and capacities. Furthermore, in conditions resembling practical adsorption environments with high humidity, the presence of H2O significantly impedes the adsorption process, leading to a nearly complete cessation of adsorption. To address these issues, metal-organic frameworks (MOFs) can be effective alternative sorbents owing to their high surface area and designable and tailorable pore properties. In addition, the wellfined crystalline structures of MOFs render in-depth study on the structure-properties relationship. However, there has been limited research on the adsorption of ROIs using MOFs, with the majority of adsorption processes relying on highly reversible physisorption. This type of ROIs adsorption not only exists in a precarious state that is susceptible to volatilization but also exhibits significantly reduced adsorption capabilities in humid environments. Thus, for the secure adsorption of the volatile ROIs, the development of sorbents capable of chemisorption is highly desirable. In this study, we focused on ROIs adsorption by electrophilic aromatic substitution with the electron-rich m-DOBDC4− (m-DOBDC4− = 4,6-dioxo-1,3-benzenedicarboxylate) present in Co2(m -DOBDC). The chemisorption of ROIs via electrophilic aromatic substitution not only leads to the formation of C-C bonds, ensuring stability but also triggers color changes in the crystal by interacting with open-metal sites and iodide ions. Leveraging these advantages, we developed an infrared radiation-based sensing method that demonstrates superior performance, exhibiting high adsorption capacities and rates, even under the challenging conditions of high-humidity practical environments.

The removal of aqueous pollutants, including dye molecules from wastewater remains one of the pressing problems in the world. Because of chemical stability and conjugated structure, dye molecules cannot be easy decomposed by heat with oxidizing reagents such as H2O2 and light. The most common representative of widespread organic pollutant is methylene blue (MB) with molecular formula C16H18ClN3S, which is important colorant and used in various chemical and biological production industries and causes serious environment problems. Porous materials, including MOFs (metal-organic frameworks) have been applied for efficient MB photocatalytic degradation. However, one of the main barriers to using most MOFs to break down aromatic organics is wide band gap energy, which means that the catalyst can exhibit high photocatalytic performance only under UVlight irradiation. Moreover, most MOFs usually show the poor water stability of frameworks, which tend to dissolve in water with total destruction. In this work we report about two new copper based MOFs with high photocatalytic properties for efficient MB degradation from wastewater under UV-light and natural sunlight. Time, required for 100% MB degradation, equals 7 minutes under UV (source 4 W 254 nm VL-4.LC UV-lamp) and 60 minutes under natural sunlight irradiation in the presence of H2O2. Crystal structure information is provided using single crystal X-ray diffraction data. The composition and comparative characteristics of MOFs are given using powder X-ray diffraction, UV–visible diffuse reflectance spectroscopy, UVvisible spectroscopy and Fourier-transform infrared spectroscopy.

유기 전구체와 금속 이온, 또는 금속-옥소 클로스터 간의 규칙적 배열을 통한 종의 다양성을 장점으로 하는 금속- 유기 골격체(Metal-Organic Frameworks, MOFs)는 에너지 사용량이 높은 상변화 기반 분리공정을 대체할 수 있는 에너지 효율 적인 막 기반 분리 기술의 개발 가능성을 열어주었다. 이에 최근 10년 동안 다결정 MOFs 분리막 합성 기술에서 상당한 진전 이 있었지만, 매우 제한된 종류의 MOFs만이 활용되고 있다. 이러한 기술 개발의 정체는 다결정 분리막의 비 선택적인 확산 경로인 결정 사이 결함(intercrystalline defects)에 대한 명확한 해결법이 없기 때문이다. 후처리 성능 제어기술(postsynthetic modifications, PSMs)은 기존 분리막을 플랫폼으로 활용하고 이를 물리적 그리고/혹은 화학적으로 처리함을 통해 분리 특성 을 개선 혹은 변경하는 기술을 말한다. PSMs 기술은 특정 분리막을 개발하는 데 있어서 새로운 MOFs를 설계하거나 막 합성 기술을 개발하지 않아도 된다는 장점이 있어서 다결정 MOF 분리막의 다양성을 제공하기 위한 새로 부상하는 전략으로 평가 된다. 본 총설에서는 PSMs 기술을 7개의 세부기술((1) 공유결합법, (2) 결정간 결함 플러깅법, (3) 결정 내부 결함 치유법, (4) 기공내 기능성 소재 함침법, (5) 기공 경화법, (6) 전구체 치환법 및 (7) 비정질화법)로 분류하고, 각 세부기술의 연구 동향 및 도전과제 그리고 향후 연구 방향에 대해 논의하고자 한다.

A porous-carbon material UiO-66-C was prepared from metal–organic frameworks UiO-66 by carbonization in inert gas atmosphere. Physicochemical properties of UiO-66-C materials were well characterized by Powder X-ray diffraction (PXRD), Scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FT-IR), Raman spectrometer, N2 adsorption/ desorption isotherms (BET), and the adsorption properties of the products were studied UiO-66-C has a high specific surface area up to 1974.17 m2/ g. Besides, the adsorption capacity of tetracycline could reach 678.19 mg/g, the adsorption processes agreed well with the pseudo-second-order kinetic model and Langmuir isotherm model.

We have prepared MIL-101/graphene oxide (GO) composites with various mixing molar ratio of Fe-containing metal– organic frameworks (MOFs) against GO. When synthesizing MOFs, it was possible to synthesize uniform crystal powders using hydrothermal method. MIL-101 consists of a terephthalic acid (TPA) ligand, with the central metal composed of Fe, which was the working electrode material for supercapacitors. Field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy analysis had been done to ascertain microstructures and morphologies of the composites. Cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge measurements were performed to analyze the electrochemical properties of the composite electrodes in 6 M KOH electrolyte. By controlling the metal ligand mole ratio against GO, we prepared a changed MOF structure and a different composite morphology, which could be studied as one of the promising optimized electrode materials for supercapacitors.

Metal–organic frameworks (MOFs) are widely used as supports for single-atom catalysts (SACs) owing to their high specific surface area, porosity, and ordered metal–ligand structure. Their activity can be increased by increasing the number of electrochemically accessible active sites via the formation of atomically dispersed metal catalysts (M–Nx) that coordinate with nitrogen atoms on the MOF. Herein, we introduce the relationship between the size of the MOF as a starting material and the catalytic activity for the oxygen reduction reaction in alkaline media. The morphology and features of the MOFs are critically dependent on their size. Remarkably, cage-like MOFs below 33 nm are converted into collapsed structures and are connected between each MOF, even carbon fiber- or tube-like features, after carbonization. SACs derived from medium-sized MOFs exhibit excellent activity and are comparable to commercial Pt/C catalysts owing to their porous structure. Therefore, we believed that controlling the size of MOFs containing active atoms is an effective method of modulating the morphological properties of the support and even the number of active sites that are closely related to the activity.

The magnetocaloric effect (MCE), which is the reversible temperature change of magnetic materials due to an applied magnetic field, occurs largely in the vicinity of the magnetic phase transition temperature. This phenomenon can be used to induce magnetic refrigeration, a viable, energy-efficient solid-state cooling technology. Recently, Metal-organic frameworks (MOFs), due to their structural diversity of tunable crystalline pore structure and chemical functionality, have been studied as good candidates for magnetic refrigeration materials in the cryogenic region. In cryogenic cooling applications, MCE using MOF can have great potential, and is even considered comparable to conventional lanthanum alloys and magnetic nanoparticles. Owing to the presence of large internal pores, however, MOF also exhibits the drawback of low magnetic density. To overcome this problem, therefore, recent reports in literature that achieve high magnetic entropy change using a dense structure formation and ligand tuning are introduced.

We developed a facile methodology for fabricating a free-standing mixed-matrix membrane (MMM) containing covalently incorporated vinyl-functionalized UiO-66-CH=CH2 particles up to 60 wt% by utilizing thiol-ene photopolymerization. FTIR, TGA, SEM, EDX, and XRD strongly supported the fact that the desired MMM containing well-dispersed UiO-66-CH=CH2 particles was successfully produced by C–S bond formation. The MMM was highly flexible and showed improved mechanical properties compared to the pristine polymeric membrane, indicating that the covalently immobilized UiO-66-CH=CH2 particles were homogeneously distributed in the polymer matrix. Gas permeability across the MMM was significantly enhanced compared with the pristine polymeric membrane as diffusion of the gas molecules was facilitated in the porous space of the MOF.

Nitrogen is a serious contaminant in natural gas because it decreases the energy density. The natural gas specification in South Korea requires a N2 content of less than 1 mol%. Thus, cost-effective N2 removal technology from natural gas is necessary, but until now the only option has been energy-intensive processes, e.g., cryogenic distillation. Using porous materials for the removal process would be beneficial for an efficient separation of CH4/N2 mixtures, but this still remains one of the challenges in modern separation technology due to the very similar size of the components. Among various porous materials, metal-organic frameworks (MOFs) present a promising candidate for the potential CH4/N2 separation material due to their unique structural flexibility. A MIL-53(Al), the most well-known flexible metal-organic framework, creates dynamic changes with closed pore (cp) transitions to open pores (ops), also called the ‘breathing’ phenomenon. We demonstrate the separation performance of CH4/N2 mixtures of MIL-53(Al) and its derivative MIL-53-NH2. The CH4/N2 selectivity of MIL- 53-NH2 is higher than pristine MIL-53(Al), suggesting a stronger CH4 interaction with NH2.