Metal-organic Framework Compound Research Articles

Porphyrin Aluminum Metal-Organic Framework in Liquid Water, its Interaction with the Oxidized Organosulfur Compound Diethyl Sulfoxide, and its Sorption from Aqueous Solution.

Oxidized organosulfur compounds and, in particular, sulfoxides are of interest as solvents in the semiconductor and pharmaceutical industry, environmental contaminants, and simulants in deactivation of chemical warfare agents. An experimental study is reported of the interaction of porphyrin aluminum metal-organic framework Al-MOF-TCPPH2 (Compound 2) with diethyl sulfoxide (DESO) in pure form and in aqueous solution. First, the suitability of Compound 2 as sorbent in aqueous solution was assessed; namely, its long-term stability (up to 15 days) in liquid water has been investigated at room temperature and under stirring. Here, a novel facile spectroscopic method has been used, a periodic micro-sampling of sorbent from suspension, followed by vacuum mini-filtration and an ex situ time-dependent attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) analysis. Next, the interaction of Compound 2 with pure liquid DESO under ambient conditions was investigated, which yields the stoichiometric adsorption complex (Al-MOF-TCPPH2)1(DESO)2 denoted Compound 3. In this adsorption complex, molecules of DESO interact with the OH group and carboxylate group of the sorbent. Then, the removal of DESO from Compound 3 was assessed, using facile treatment with warm water in the micro Soxhlet apparatus followed by the ATR FT-IR analysis. Finally, Compound 2 was tested in sorption of DESO from diluted aqueous solution. In the initial step, the sorption proceeds very quickly (in <1 min the concentration of DESO decreases by about 20%) followed by a much slower step. The maximum amount of adsorbed DESO corresponds to half of the amount adsorbed from pure DESO as found by the high-performance liquid chromatography-ultraviolet detection method. This adsorbed amount corresponds to 1 mol DESO adsorbate per mol of sorbent. Porphyrin aluminum metal-organic framework Compound 2 is promising for the removal of DESO from diluted aqueous solution, and it is of interest for the removal of similar oxidized organosulfur compounds.

Porous Ruthenium-Tungsten-Zinc Nanocages for Efficient Electrocatalytic Hydrogen Oxidation Reaction in Alkali.

With the rapid development of anion exchange membrane technology and the availability of high-performance non-noble metal cathode catalysts in alkaline media, the commercialization of anion exchange membrane fuel cells has become feasible. Currently, anode materials for alkaline anion-exchange membrane fuel cells still rely on platinum-based catalysts, posing a challenge to the development of efficient low-Pt or Pt-free catalysts. Low-cost ruthenium-based anodes are being considered as alternatives to platinum. However, they still suffer from stability issues and strong oxophilicity. Here, we employ a metal-organic framework compound as a template to construct three-dimensional porous ruthenium-tungsten-zinc nanocages via solvothermal and high-temperature pyrolysis methods. The experimental results demonstrate that this porous ruthenium-tungsten-zinc nanocage with an electrochemical surface area of 116 m2 g-1 exhibits excellent catalytic activity for hydrogen oxidation reaction in alkali, with a kinetic density 1.82 times and a mass activity 8.18 times higher than that of commercial Pt/C, and a good catalytic stability, showing no obvious degradation of the current density after continuous operation for 10,000 s. These findings suggest that the developed catalyst holds promise for use in alkaline anion-exchange membrane fuel cells.

Recent Advances in Catalytic Compounds Developed by Thermal Treatment of (Zr-Based) Metal–Organic Frameworks

Metal–organic frameworks (MOFs) have been the subject of extensive scientific investigation in the last three decades and, currently, they make up one of the types of compounds most studied for their potential application in a wide range of distinct catalytic processes. Pristine MOF compounds provide several intriguing benefits for catalytic applications, including large interior surface areas and high densities of active sites; high catalytic reaction rates per volume; post-synthesis modifications with complementary catalytic groups; and the ability for multiple functional groups to catalyze the reaction. For most large-scale catalytic applications, including those in fuel processing, gas emission reduction, and chemical synthesis, pristine MOFs often show limited stabilities and opportunities for regeneration at high temperatures. As a result, the real applications of MOFs in these technologies are likely to be constrained, and a controlled thermal modification to prepare MOF-derivative compounds has been applied to induce crystalline structural changes and increase the structural stability of the MOFs, enhancing their potential applicability in more severe catalytic processes. Recent advances concerning the use of this strategy to boost the catalytic potential of MOF-derivative compounds, particularly for stable Zr-based MOFs, are outlined in this short review article.

Localizing bismuth single atoms around tin nanoparticles for efficient CO2 reduction and fabrication of high-performance sodium-ion batteries

The utilization of Bi/Sn alloy-based materials has garnered significant interest as a promising avenue for the development of sodium-ion batteries and the achievement of electrocatalytic CO2 reduction. This is due to their notable attributes of high theoretical specific capacity and low working potential, as well as their abundance and high catalytic activity. Nevertheless, the practical application potential of these alloys is restrained by their inadequate electrical conductivity without incorporating conductive carbon networks to improve the electrical conductivity of the composite material and consequential volumetric fluctuations, which ultimately lead to unsatisfactory cycle life and the depletion of active components. A single-atom Bi-coated Sn nanoparticle was synthesized utilizing metal-organic framework (MOF) compounds as precursors. The resulting composite exhibits the ability to mitigate volume changes that arise during charge and discharge processes, while also enhancing the catalytic activity of the system for CO2 reduction through synergistic effects. Upon pyrolysis of the MOFs at elevated temperatures, a carbon matrix "protective layer" is formed to prevent the loss of active substances under conditions of electrode pulverization. This leads to improved cycle stability and coulomb efficiency of the battery. The ion permeation and gas diffusion are facilitated by the three-dimensional porous structures of composites. The conductive networks further improve the conductivity of materials, prevent the shedding of electrode material from electrodes, and facilitate electron transport. Consequently, the electrode demonstrates exceptional electrochemical performance, as evidenced by a high capacity of 510 mAh g−1 after 1000 cycles and a reversible capacity of 497 mAh g−1 after 500 cycles. Furthermore, the composite material demonstrates a notable degree of selectivity towards CO2 reduction, as evidenced by a coulombic efficiency of 95.7% for HCOOH at a potential of −1.1 V but only a coulombic efficiency of 2.3% for H2. Furthermore, the composite material exhibits commendable stability. The findings presented in this study offer valuable technical insights towards the attainment of carbon neutrality and carbon peaking.

Metal organic framework (MOF): Synthesis and fabrication for the application of electrochemical sensing

Metal-organic frameworks (MOF) are a class of porous hybrid materials of metal ions linked by organic bridging ligands. These materials consist of different families of crystalline frameworks with metal ions and metal-ion clusters linked by the coordination bonds with suitable organic ligands. These porous materials possess high surface area, variable pore sizes, various functions, and excellent thermal stability. As a result, these unique and tailored MOF materials found varied applications in electrochemical sensor development. The review critically examines the approach to synthesizing a wide range of MOF compounds. The utilization of MOF in fabricating a small-scale sensor device demonstrates the ability to detect various water contaminants in aquatic environments. Moreover, it showcased an in-depth advancement in sensor and device development utilizing MOFs materials. The efficient use of electrochemical sensors is discussed critically and presents these studies’ challenges and future perspectives.

MOF-derived NiAl2O4/NiCo2O4 porous materials as supercapacitors with high electrochemical performance.

Metal-organic framework compounds are extensively utilized in various fields, such as electrode materials, owing to their distinctive porous structure and significant specific surface area. In this study, NiCoAl-MOF metal-organic framework precursors were synthesized by a solvothermal method, and NiAl2O4/NiCo2O4 electrode materials were prepared by the subsequent calcination of the precursor. These materials were characterized by XRD, XPS, BET tests, and SEM, and the electrochemical properties of the electrode materials were tested by CV and GCD methods. BET tests showed that NiAl2O4/NiCo2O4 has an abundant porous structure and a large specific surface area of up to 105 m2 g-1. The specific capacitance of NiAl2O4/NiCo2O4 measured by the GCD method reaches up to 2870.83 F g-1 at a current density of 1 A g-1. The asymmetric supercapacitor NiAl2O4/NiCo2O4//AC assembled with activated carbon electrodes has a maximum energy density of 166.98 W h kg-1 and a power density of 750.00 W kg-1 within a voltage window of 1.5 V. In addition, NiAl2O4/NiCo2O4 materials have good cycling stability. These advantages make it a good candidate for the application of high-performance supercapacitors.

Never-Ending Story: New Cyclodextrin-Based Metal-Organic Framework Crystal Structures Obtained Using Different Crystallization Methods.

Six novel cyclodextrin (CD)-based metal-organic frameworks (MOFs) were synthesized using distinct crystallization methodologies. A modified vapor diffusion method is introduced for the first time, termed fast crystallization, which enables the rapid solid-state formation of MOF compounds. This innovative method yielded four of the newly synthesized MOFs. The crystal structures of five obtained frameworks were structurally characterized through single-crystal X-ray diffraction, while one, compound 5 (γ-CD-K-5), was additionally characterized as a bulk powder. Structural analysis revealed that two of the newly obtained MOFs, namely, compound 2 (α-CD-K-2) and compound 3 (α-CD-Rb-3), exhibited isostructural characteristics, forming a three-dimensional (3D) framework. Compound 1 (α-CD-K-1) shared the same space group as EVEGET (α-CD-K) and displayed the same framework type. Furthermore, the crystal packing of compound 4 (β-CD-K-4) closely resembled that of compound 1 and EVEGET, with the only distinction lying in the type of CD employed. Notably, compound 6 (γ-CD-K-6) incorporated an iodine ion with an occupancy of 0.2. To discern the intermolecular interactions within the obtained MOFs, the Hirshfeld surface was calculated using Crystal Explorer software.

Discovery and Synthesis Optimization of Isoreticular Al(III) Phosphonate-Based Metal-Organic Framework Compounds Using High-Throughput Methods.

High-throughput (HT) methods are an important tool for the fast and efficient screening of synthesis parameters and the discovery of new materials. This manuscript describes the synthesis of metal-organic frameworks (MOFs) from solution using an HT reactor system, resulting in the discovery of various phosphonate-based MOFs of the composition [Al2H12-x(PMP)3]Clx∙6H2O (H4PMP = N,N '-piperazine bis(methylenephosphonic acid)) for x = 4, 6, denoted as Al-CAU-60-xHCl, containing trivalent aluminum ions. This was accomplished under solvothermal reaction conditions by systematically screening the impact of the molar ratio of the linker to the metal and the pH of the reaction mixture on the product formation. The protocol for the HT investigation includes six steps: a) synthesis planning (DOE = design ofexperiment) within the HT methodology, b) dosing and working with in-house developed HT reactors, c) solvothermal synthesis, d) synthesis workup using in-house developed filtration blocks, e) characterization by HT powder X-ray diffraction, and f) evaluation of the data. The HT methodology was first used to study the influence of acidity on the product formation, leading to the discovery of Al-CAU-60∙xHCl (x = 4 or 6).

Electrochemical Performance and Mechanism of Bimetallic Organic Framework for Advanced Aqueous Zn Ion Batteries.

Widespread interest has been generated by aqueous zinc batteries (AZIBs), which have excellent theoretical capacities (820 mA h g-1), a low redox potential (-0.76 V vs SHE of Zn metal), and high security. Suitable cathodes for constructing high performance AZIBs are of great signification. Metal-organic frameworks (MOFs) with adjustable structure via metals and organic units show great potential in AZIBs. In this work, ZnMn-Squaric acid (ZnMn-SQ) was synthesized using squaric acid through coprecipitation and served as the cathode for AZIBs. The ZnMn-SQ electrode demonstrated a high capacity of 489.1 mA h g-1 at 0.2 A g-1. Meanwhile, ZnMn-SQ can obtain 80.7 mA h g-1 after 1300 cycles, showing an outstanding long cycle life. More importantly, ex situ characterizations of XRD, XPS, and FT-IR revealed that ZnMn-SQ undergoes a structural transformation from the initial ZnMn-SQ framework to manganese oxide accompanied by Zn-SQ and then reduced to MnOOH, ZnMn2O4, and Zn4SO4(OH)6·5H2O (ZHS) in subsequent cycles. In addition, a modified zinc anode using cubic porous Zn-SQ-3d was used to construct ZnMn-SQ // Zn-SQ-3d@Zn(Zn-SQ-3d-coated Zn) high performance AZIBs, the capacity of which reaches 171.3 mA h g-1 at 1 A g-1 after 660 cycles. This work provided chances for constructing high-performance zinc ion batteries using MOF compounds.

Enhanced Thermal Decomposition and Safety of Spherical CL-20@MOF-199 Composites via Micro-Nanostructured Self-Assembly Regulation.

The characteristics of high burning rate, high energy output, and low pressure exponent have always been the focus of development in the field of composite solid rocket propellants. In this paper, a metal-organic framework (MOF-199) compound is introduced to prepare micro-nanospherical CL-20@MOF-199 composites via the spray-drying self-assembly technique to reach the above goals. MOF-199, which acts as an attractive combustion catalyst and a safety regulator, is uniformly coated on the surface of CL-20 with close interface contact between particles, effectively accelerating the thermal decomposition of CL-20 and ensuring safety performance. The average noncovalent interaction (aNCI) analysis illustrates that there are strong C-H···O hydrogen bonds and van der Waals interaction between CL-20 and MOF-199 molecules, greatly enhancing the effect of interparticle assembly. The effects of different contents of MOF-199 on the thermal, safety, and energy properties of CL-20 were discussed. The thermal analysis demonstrates that MOF-199 has a significant thermal catalytic effect on CL-20, with an advanced peak temperature of thermal decomposition of 14.2 °C and a reduced activation energy barrier of 34.2 kJ·mol-1, mainly benefitting from more exposed catalytic active sites and close interface contact. In addition, CL-20@MOF-199 composites exhibit decreased mechanical sensitivity (IS: 21-40 cm, FS: 80-240 N) and excellent energy performance. This work clearly demonstrates that MOF-199 is both a superior combustion catalyst and a good safety buffer for CL-20, and it opens new potential for further applications of CL-20 in composite solid propellants.

Chiral "doped" MOFs: an electrochemical and theoretical integrated study.

This work reports on the electrochemical behaviour of Fe and Zn based metal-organic framework (MOF) compounds, which are "doped" with chiral molecules, namely: cysteine and camphor sulfonic acid. Their electrochemical behaviour was thoroughly investigated via "solid-state" electrochemical measurements, exploiting an "ad hoc" tailored experimental set-up: a paste obtained by carefully mixing the MOF with graphite powder is deposited on a glassy carbon (GC) surface. The latter serves as the working electrode (WE) in cyclic voltammetry (CV) measurements. Infrared (IR), X-ray diffraction (XRD) and absorbance (UV-Vis) techniques are exploited for a further characterization of the MOFs' structural and electronic properties. The experimental results are then compared with DFT based quantum mechanical calculations. The electronic and structural properties of the MOFs synthesized in this study depend mainly on the type of metal center, and to a minor extent on the chemical nature of the dopant.

Prussian blue (PB) modified gold nanoparticles as a SERS-based sensing platform for capturing and detection of pyrazinoic acid (POA)

Pyrazinoic acid (POA) is a metabolite of the anti-tuberculosis drug pyrazinamide (PZA), and its detection can be used to assess the resistance of Mycobacterium tuberculosis in cultures, as only sensitive strains of the bacteria can metabolize PZA into POA. Prussian blue is a well-known metal-organic framework compound widely used in various sensing platforms such as electrochemical, photochemical, and magnetic sensors. In this study, we present a novel sensing platform based on Prussian blue-modified gold nanoparticles (AuNPs) designed to enhance the affinity of POA towards the sensing surface and to capture POA molecules from aqueous solutions. This SERS-based method allows for the selective enrichment of POA, which can be detected in both pure aqueous solution and in the presence of its pro-drug PZA. The limit of detection (LOD) for POA was estimated to be 1.08 μM in pure aqueous solution and 0.18 mM in the presence of PZA. Furthermore, the precision of the SERS method was verified by the relative standard deviation (RSD) of 3.34–12.02% for three parallel samples using different matrices, i.e. aqueous solution, spiked river water and spiked simulated saliva. The recoveries of the samples ranged from 92.65 to 118.51%. These all demonstrate the potential application of the proposed detection scheme in medical research.

Recent Progress of Multiferroicity and Magnetoelectric Effects in ABX3‐Type Perovskite Metal–Organic Frameworks

AbstractMultiferroics have been investigated extensively in the last decades due to their wide range of applications in high‐density multistate storage, spintronics, and novel multifunctional magnetic–electric devices. One peculiar subgroup of multiferroic materials comprises 3D perovskite metal–organic frameworks (MOFs) with the general formula ABX3 (A = monovalent organic cation (such as an alkali metal or protonated amine), B = divalent metal cation, X = organic anion), for their coexistence of multiple orders (electric, magnetic, and elastic, et al.). The purpose of this review is to give a representative overview of the recent progress in the field of ABX3‐type multiferroic MOFs, containing 3d magnetic metal ions at B‐site. First, the perovskite multiferroic MOFs in which X‐site is occupied by formate, is examined and summarized. In particular, magnetoelectric coupling effects, such as electric‐field tuning of magnetic properties and magnetic field control of electric polarization, and pressure control of structural/magnetic/electric properties, are described and discussed. Then, it is focused on the structural phase transitions and ferroic orders by analyzing several representative multiferroic MOFs compounds with none‐formate. To motivate the researchers in this area, some promising topics that have not yet been fully explored in perovskite multiferroic MOFs are finally proposed.

Elasticity of Dense Metal–Organic Framework Compounds

Elasticity of Dense Metal–Organic Framework Compounds

Fe, N-codoped carbon derived from different ligands for oxygen reduction reaction in air-cathode microbial fuel cells: Performance comparison and the associated mechanism

In order to clarify the effect of iron ligands on properties, catalysts with different structure through four kinds of ligands are prepared and the oxygen reduction reaction (ORR) activity and the maximum power density in microbial fuel cells (MFCs) are compared. The formed Fe single atoms, the metal-organic framework compound, the Prussia blue crystal and ethylenediamine coordination compound (Phen-Fe, PA-Fe, PB-Fe and EDA-Fe) exhibit the maximum power densities of 2041 ± 23 mW m−2, 1656 ± 32 mW m−2, 1062 ± 31 mW m−2, and 1865 ± 36 mW m−2, respectively. In addition, the electrochemical performance of four catalysts with different structures is significantly different, and the higher exchange current density and 4-electron pathway of Phen-Fe explained the kinetics of ORR. The structures and surface properties are explored through a series of characterizations. The different amounts of nitrogen functionalities, Fe ion, and high graphitization degree are thought to facilitate electron transfer, lower Rct and improve ORR activity. In sum, the iron ligands have a great influence on the structure and performance of catalysts, and the single-atom structure and ethylenediamine coordination structure are proved to be promising structures for ORR in MFCs.

Recent advances for water-stable metal-organic frameworks (MOFs)

Metal-organic framework (MOF) compounds have been widely studied and explored for many years due to their diversity of structure and composition. It is a new kind of framework material because of its high specific surface area, high porosity, and adjustable pore structure and internal environment. It has unlimited development prospects in gas storage, separation, catalysis, chemical sensing, and other related fields. Therefore, MOFs have attracted great and extensive attention. This paper mainly summarizes MOFs materials with good water stability, and stability of MOFs compounds under various harsh environmental conditions was analyzed, and the synthetic method and properties of these MOFs materials were summarized. In conclusion, this paper for the summary of the water-resistant MOFs compounds is helpful to provide a good guide to finding or creating other novel water stability MOFs functional materials.

NiCoSe4@CNFs derived from MOF compounds enabling robust polysulfide adsorption and catalysis in Li-S batteries

The availability of lithium sulfur (Li-S) batteries is significantly constrained by the severe shuttle effect and sluggish conversion kinetics of polysulfides (LiPSs). Here, we construct the catalytic NiCoSe4/carbon nanofibers interlayer composite (NiCoSe4 @CNFs) to restrict shuttle effect and accelerate the polysulfides conversion. The NiCoSe4 derived from metal organic framework (MOF) retains the advantage of CoSe2 in chemical adsorption for polysulfide, and Ni doping offers superior electrocatalytic activity. Meanwhile, the carbonization of MOF ensures the NiCoSe4 superior electrical contact with the derived carbon materials. In addition, CNFs build conductive carbon matrix for the growth of NiCoSe4 on the surface to facilitate the electron transfer during charging and discharging process. Benefit from the unique structure, NiCoSe4 @CNFs as interlayer can quickly and effectively carry out the strategy of polysulfides adsorption followed by simultaneously catalysis. Batteries with a NiCoSe4 @CNFs interlayer can deliver excellent performance with a stable cycle performance after 500 cycles (residual capacity of 74 %) at 2 C and a high discharge specific capacity of 1019.5 mAh g−1 at 0.5 C. Achieving robust polysulfide adsorption and electrocatalytic activity in NiCoSe4/carbon nanofibers interlayer opens previously unexplored avenues towards advanced separation technologies and energy-harvesting devices.

Challenges in Developing MOF-Based Membranes for Gas Separation.

Metal-organic frameworks (MOFs) are promising candidates for membrane gas separation. MOF-based membranes include pure MOF membranes and MOF-based mixed matrix membranes (MMMs). This Perspective discusses the challenges for the next stage of the development of MOF-based membranes based on research conducted in the past decade. We focused on three major issues associated with pure MOF membranes. First, some MOF compounds have been overstudied, despite the availability of numerous MOFs. Second, gas adsorption and diffusion in MOFs are often independently investigated. The correlation between adsorption and diffusion has seldom been discussed. Third, we identify the importance of characterizing the gas distribution in MOFs to understand the structure-property relationships for gas adsorption and diffusion in MOF membranes. For MOF-based MMMs, engineering the MOF-polymer interface is essential for achieving the desired separation performance. Various approaches to modify the MOF surface or polymer molecular structure have been proposed to improve the MOF-polymer interface. Herein, we present defect engineering as a facile and efficient approach for engineering the MOF-polymer interfacial morphology and its extended application for various gas separations.

Supernano Crystals Boost the Initial Coulombic Efficiency and Capacity of Copper Benzene-1,3,5-Tricarboxylate for Li-Ion Batteries

Despite the high capacity of metal–organic framework (MOF) electrodes for Li-ion batteries (LIBs), the low initial Coulombic efficiency (ICE) due to irreversible and massive consumption of lithium ions in the initial cycle hinders their practical application. Nanoscale transition metal oxides (TMOs) can activate the electrochemically stable Li–O bonds and therefore improve the ICE. Hence, copper benzene-1,3,5-tricarboxylate (Cu-BTC) rods with encapsulated supernano CuO were synthesized in a straightforward way using CuO and H3BTC as the metal source and organic ligand, respectively. By altering the reaction temperature, the size of CuO crystals can be adjusted from 6.98 to 2.72 nm. The CuO-doped Cu-BTC (40 °C) anode delivers an optimal capacity of 990.7 mA h g–1 (under 0.2 A g–1) after 100 cycles and the highest ICE of 61.84%, which exceeds the other counterparts. Such superior electrochemical properties are closely related to the size and content of CuO. This strategy introduces supernano CuO into Cu-BTC, which can be generalized to construct other in situ-formed TMO-doped MOF compounds as efficient lithium storage materials.

Structural Properties of Metal-Organic Frameworks at Elevated Thermal Conditions via a Combined Density Functional Tight Binding Molecular Dynamics (DFTB MD) Approach.

The performance of different density functional tight binding (DFTB) methods for the description of six increasingly complex metal-organic framework (MOF) compounds have been assessed. In particular the self-consistent charge density functional tight binding (SCC DFTB) approach utilizing the 3ob and matsci parameter sets have been considered for a set of four Zn-based and two Al-based MOF systems. Moreover, the extended tight binding for geometries, frequencies, and noncovalent interactions (GFN2-xTB) approach has been considered as well. In addition to the application of energy minimizations of the respective unit cells, molecular dynamics (MD) simulations at constant temperature and pressure conditions (298.15 K, 1.013 bar) have been carried out to assess the performance of the different DFTB methods at nonzero thermal conditions. In order to obtain the XRD patterns from the MD simulations, a flexible workflow to obtain time-averaged XRD patterns from (in this study 5000) individual snapshots taken at regular intervals over the simulation trajectory has been applied. In addition, the comparison of pair-distribution functions (PDFs) directly accessible from the simulation data shows very good agreement with experimental reference data obtained via measurements employing synchrotron radiation in case of MOF-5. The comparison of the lattice constants and the associated X-ray diffraction (XRD) patterns with the experimental reference data demonstrate, that the SCC DFTB approach provides a highly efficient and accurate description of the target systems.