Metal-organic Framework Catalyst Research Articles

Synthesis and Characterization of Cobalt–Organic Framework as an Electrocatalyst for Water Splitting Application

ABSTRACTClimate change is seen as a crucial environmental dilemma that humanity will confront in the upcoming decade. For this purpose, the solvothermal‐assisted technique is used to create metal–organic frameworks (MOFs), which are porous materials characterized by strong connections between organic ligands and metal ions. The MOF discussed here contains cobalt as the metal node and a linker derived from 2‐aminobenzoic acid and terephthalaldehyde. The prepared powder underwent analysis using various techniques including Fourier‐transform infrared spectroscopy (FT‐IR), powder X‐ray diffraction (PXRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area measurement, and thermal analysis. BET analysis revealed a surface area of 1587.06 m2/g, a total pore volume of 0.86394 cc/g, and an average pore size of 1.088 nm. The RGO@Co‐MOF prepared was utilized to evaluate water splitting efficiency, demonstrating favorable catalytic activity like most reported modified MOF catalysts under low current density conditions of 10 mA/cm2.

Regulating the Microenvironment of Zn‐Based Metal‐Organic Framework for Enhanced CO2 Electroreduction to Formate

Electrocatalytic CO2 reduction (ECR) has emerged as one of the most promising strategies to alleviate the energy crisis and CO2 pollution, for which a wide variety of catalysts are under development. Metal‐organic frameworks (MOFs) with clear and designable structures are an excellent platform for ECR. Here, two isostructural N, O‐coordinated Zn‐MOFs, FJU‐126‐4F and FJU‐126‐CH3, based on terephthalic acid ligand with different groups (one is ‐4F, the other is ‐CH3) on the benzene ring, have been constructed for ECR catalysts. Significantly, the different functional groups make the performance difference of ECR. The maximum Faraday efficiency of formate (FEformate) for FJU‐126‐4F is 60.5% with the partial current density of formate (jformate) of ‐19.35 mA cm‐2 at ‐1.47 V, while the optimum FEformate of FJU‐126‐CH3 is 50.2% with the jformate of ‐10.04 mA cm‐2 at ‐1.57 V. The work provides insight into the rational design of MOF catalysts for ECR.

Application of Ni‐Based MOFs Catalyst in Oxidative Coupling Reaction of Benzylamine

AbstractNanoparticles made of porous coordination polymers, known as metal‐organic frameworks (MOFs), are becoming increasingly popular in nanomaterials research, especially in catalytic applications. With their intricate architectures, MOFs make it possible to incorporate metal nodes, encapsulate substrates, and use functional linkers, all of which contribute to synergistic engineering. A Ni‐based metal‐organic framework sample was prepared by the solvothermal method with NiCl2.6H2O as a precursor of Ni metal and terephthalic (H2BDC) acid as a linker. The as‐synthesized NiBDC was verified by X‐ray diffraction (XRD), Fourier‐transform infrared spectroscopy (FT‐IR), scanning electron microscopy (SEM), scanning electron microscopy with energy dispersive X‐ray spectroscopy (SEM‐EDX), transmission electron microscopy (TEM), and N2 adsorption/desorption isotherms. Based on these findings, we applied the as‐synthesized NiBDC to the oxidative coupling reaction of benzylamine. The results revealed that with NiBDC as a heterogeneous catalyst, the oxidative coupling reaction of benzylamine achieved a performance of 92%. Furthermore, the catalyst maintains good stability after four catalytic cycles, with an efficiency of approximately 82%.

CH4 Carbonylation to Acetic Acid Using H2O as an Oxidant on a Rh-Functionalized UiO-67 Combined with Oriented External Electric Fields: Selectivity and Mechanistic Insights from DFT Calculations.

Acetic acid (CH3COOH), as an industrially important petrochemical product, is predominantly produced via multistep energy-intensive processes. The development of a rhodium single-site heterogeneous catalyst has received considerable attention due to its potential to transform CH4 into CH3COOH in a single step. Herein, the reaction mechanism for the generation of CH3COOH from CH4, CO, and H2O catalyzed by Rh-functionalized metal-organic framework (MOF) UiO-67 and the selectivity of products CH3COOH, formic acid (HCOOH), methanol (CH3OH), and acetaldehyde (CH3CHO) under the oriented external electric fields (OEEFs) were systematically explored by density functional theory (DFT) calculations. The results reveal that the insertion of CO into Rh-CH3 is the rate-determining step with a free energy barrier of 21.0 kcal/mol in CH4 carbonylation to CH3COOH. Upon applying an OEEF of Fx = +0.0050 au along the C-C bond, the rate-determining step shifts toward H2O decomposition with the barrier of 19.6 kcal/mol, significantly improving the selectivity for CH3COOH production, compared to the major competitive HCOOH route. The Brønsted-Evans-Polanyi (BEP) relationships between key transition states, field strength, and NPA charge transfer were established. This study may guide the rational design of atomically dispersed MOF catalysts for the selective coconversion of CH4 and CO to CH3COOH using H2O as the oxidant under the OEEF.

Molecular Architecture @ MOFs: Designing a Multifunctional Catalyst for the Cascade Reaction of Olefins via Epoxides to Cyclic Carbonates

Employing enzymatic reaction cascade principles to synthesize artificial materials with multiple autonomously operating active sites is one of the holy grails in modern catalysis research. In this regard, metal‐organic frameworks (MOFs) are promising host platforms. Yet, applying MOFs as enzyme‐mimicking catalysts is synthetically challenging. Herein, we present a design strategy for the synthesis of porphyrin‐based MOFs for the cascade catalysis of the conversion of olefins to epoxides and their cycloaddition with CO2 to cyclic carbonates. The MOFs feature tunable dual active sites with synthetically controllable metal variations. A clear dependence of the metal combination on the catalytic performance of the MOF catalysts is shown. This work advances the understanding essential for designing sophisticated, multifunctional porphyrin MOFs for efficient one‐pot cascade catalysis.

One-pot synthesis of 2D-Ni-MOF from waste PET plastic in aqueous medium for selective electrooxidation of glycerol, ethanol, and methanol

This study investigates the electrochemical performance and selectivity of a nickel-based metal-organic framework (Ni-MOF) catalyst synthesized from waste PET plastic using a one-pot approach in aqueous media. The Ni-MOF electrode was evaluated for glycerol electrooxidation reaction (GEOR), ethanol electrooxidation reaction (EEOR), and methanol electrooxidation reaction (MEOR). Linear sweep voltammetry (LSV) revealed current densities of 30mA/cm² at 0.5639V for GEOR, 50.07mA/cm² at 0.35V for EEOR, and 45.73mA/cm² at 0.39V for MEOR, indicating superior catalytic activity. Nyquist plots showed lower charge transfer resistance (Rct) values of 11.0 Ω for GEOR, 2.79 Ω for EEOR, and 2.69 Ω for MEOR, confirming efficient electron transfer. Bode impedance plots demonstrated lower impedance for alcohol electrooxidation compared to oxygen evolution reaction (OER). Chronoamperometry (CA) tests indicated excellent stability with 75.72% glycerol conversion for GEOR and selectivities of 94% for glyceric acid, 65.59% for acetic acid in EEOR, and 70.54% for formic acid in MEOR. These results highlight the potential of Ni-MOF derived from recycled PET plastic for sustainable and efficient electrooxidation of C1-C3 alcohols.

Electrolyte Composition‐Dependent Product Selectivity in CO2 Reduction with a Porphyrinic Metal–Organic Framework Catalyst

AbstractA copper porphyrin‐derived metal–organic framework electrocatalyst, FICN‐8, was synthesized and its catalytic activity for CO2 reduction reaction (CO2RR) was investigated. FICN‐8 selectively catalyzed electrochemical reduction of CO2 to CO in anhydrous acetonitrile electrolyte. However, formic acid became the dominant CO2RR product with the addition of a proton source to the system. Mechanistic studies revealed the change of major reduction pathway upon proton source addition, while catalyst‐bound hydride (*H) species was proposed as the key intermediate for formic acid production. This work highlights the importance of electrolyte composition on CO2RR product selectivity.

Singlet oxygen dominant-activation by hollow structural cobalt-based MOF/peroxymonosulfate system for micropollutant removal

Despite the keen interest in potentially using the metal-organic framework (MOF) in advanced oxidation processes (AOPs), their application for environmental abatement and the corresponding degradation mechanisms have remained largely elusive. This study explores the use of cobalt-based MOF (CoMOF) for peroxymonosulfate (PMS) activation to remove tetracycline (TC) from water resources. Under optimal conditions, the given catalytic system could achieve a TC removal of 83.3%. Radical quenching tests and EPR analysis revealed that SO4•–, HO•, •O2−, and 1O2 could participate in the catalytic degradation, but the discernible removal mechanism was mainly ascribed to the nonradical pathway induced by 1O2. At only 5 mg/L of CoMOF, the performance of the catalytic system was superior to that of PMS alone for different types of micropollutants. The CoMOF/PMS system could also reliably deal with typical anions in water, such as Cl−, SO42−, HCO3−, and PO43−. The MOF catalyst could last for four cycles with a minor decrease in reactivity of ∼30%. However, the removal performance decreased markedly when aromatic natural organic matter (NOM) were present in the water bodies, and the effectiveness was lower in alkaline or acidic environments. Our work offers insights into the catalytic degradation of CoMOF/PMS applied in contaminated water remediation and serves as a baseline for fabricating an efficient MOF with enhanced catalytic performance and stability.

Enhanced carbon dioxide reduction in microbial electrosynthesis using amine-functionalized metal-organic framework catalyst

Microbial electrosynthesis (MES) is a promising technology that can reduce carbon dioxide (CO2) into valuable platform chemicals using microbial biocatalytic action. However, inefficient microbe-electrode interactions greatly reduce the current uptake by microbes, ultimately hampering the CO2 reduction reaction. Therefore, this study aimed to enhance microbe-electrode interaction using amine-functionalized metal-organic framework (MOF) catalysts such as NH2-UiO-66(Zr) and NH2-UiO-66(Zr/Ni) on the cathode. Both abiotic and biotic cyclic voltammetry (CV) revealed the highest reduction current response from the NH2-UiO-66(Zr/Ni)-modified cathode among the tested cathodes, such as NH2-UiO-66, Pt-C, and unmodified cathode (control). Thus, the MES using the NH2-UiO-66(Zr/Ni) cathode could achieve an acetic acid production rate of 1166 ± 31 mg/L·d at a coulombic efficiency of 76 ± 2 %, which was higher than the MES operations with NH2-UiO-66(Zr) and without catalyst with corresponding values of 912 ± 12 mg/L·d and 67 ± 3 %, and 428 ± 13 mg/L·d and 56 ± 4 %, respectively. Biofilm analyses using scanning electron microscopy and confocal microscopy showed thick biofilm development on the NH2-UiO-66(Zr/Ni) cathode with abundant live bacteria. The results suggest that the amine-functionalized MOF can enhance the interaction of microbes with the cathode, resulting in efficient and high-rate bioelectrochemical CO2 reduction to valuable organic chemicals.

Cu-Fe bimetallic MOFs with long lifetime separated-state charge for enhancing selectivity for CO2 photoreduction to CH4

Improving the CO2 to CH4 conversion efficiency of Cu metal-organic frameworks (Cu-MOFs) catalysts is important for promoting carbon capture and utilization. In this work, a series of novel Cu-Fe bimetallic MOFs photocatalysts (Cu-BTB-Fe with 0.5 wt%, 1.0 wt%, 2.0 wt%, and 4.0 wt% of Fe; H3BTB = 1,3,5-tris(4-carboxyphenyl) benzene) were synthesized by a bimetallic site (Cu and Fe) design strategy in order to improve the electron-hole separation efficiency and CO2 adsorption activation. Findings indicated that the as-synthesized Cu-BTB-2 wt% Fe catalyst exhibited excellent catalytic performance for the conversion of CO2 to CH4 and CO under simulated sunlight irradiation, providing a yield of 32.20 μmol∙g−1∙h−1 and a selectivity of 69.24 % for CO2 to CH4 conversion as well as a yield of 14.29 μmol∙g−1∙h−1 for CO2 to CO conversion without liquid phase products. This is because the Cu-Fe bimetallic sites can continuously supply photoinduced electrons with long separated-state decay lifetime to efficiently activate CO2. Specifically, the Cu-BTB-Fe catalysts provided a high proportion of effective photoinduced electrons with long decay lifetime for the CO* hydrogenation process through a unique electron transfer mechanism, while the strong affinity between CO2 and [Cu2(COO)4]-Fe active units enabled high CO2 adsorption activation and rapid CO2 reduction. The present approach, hopefully, would help to establish feasible pathway for the development of novel highly selective Cu-based MOFs photocatalysts for CO2 photocatalytic reduction yielding CH4.

Enhanced Local Ion Transport in High-Performance Anion Exchange Membrane Water Electrolyzers Via Quaternary Ammonium-Functionalized Metal-Organic Framework Electrocatalysts

Anion-exchange membrane water electrolyzers (AEMWEs) present a multitude of advantages, particularly in the utilization of non-platinum group (non-PGM) catalysts. While diverse catalysts have demonstrated notable electrocatalytic activity in alkaline conditions, the integration of the ionomer with the electrocatalyst at the active catalyst layer is crucial for enhancing overall AEMWE performance in practical device demonstrations by improving mass transport. However, the intrinsic instability of polymeric ionomers, leading to physical detachments or alkaline (chemical) degradation, poses a challenge that can potentially diminish performance. In this study, drawing inspiration from the aforementioned ionomer chemistry, we introduce non-PGM NiFe-based metal-organic frameworks (MOFs) incorporating quaternary ammonium (QA) cation moieties covalently functionalized to benzenedicarboxylic acid (BDC) ligands as promising electrocatalysts for the oxygen evolution reaction (OER) in alkaline environments. Three specifically designed functional groups with varying ion exchange capacities (IEC) and alkaline stability—trimethylamine (TMA), N-methylpyrrolidine (C4N), and N-methylpiperidine (C5N)—were directly tethered to BDC ligands. The alkaline OER activity of Ni2Fe1-QA-MOF was meticulously assessed using rotating disk electrodes and AEMWE devices. These directly tethered QA groups markedly facilitated improved ionic transport of OH- ions at the catalyst/electrolyte interfaces compared to BDC ligands, ultimately leading to a significant enhancement in half-cell activity and AEMWE performance. In-situ IR/RAMAN spectroscopy revealed that QA moieties highly promoted local ionic transport at the interfaces, as evidenced by characteristic peaks indicating a robust interaction between QA and OH- ions. Unexpectedly, QA moieties not only contributed to ionic transport in local environments but also induced oxidation states of Ni metal sites, while Fe sites exhibited no changes during the applied potential in the OER region, as comprehensively revealed by synchrotron X-ray absorption spectroscopy (XAS). In comparison with conventional NiFe layered double hydroxide (LDH) structures, we posit that the substantial structural transformation of Ni moieties can be attributed to an increased degree of M-O bond interaction, enhanced by the local interaction between QA and OH- ions. Density functional theory (DFT) calculations also validate the balanced adsorption of OER intermediates on QA-MOFs. Finally, QA-NiFe-MOF was directly synthesized on a porous transport layer (PTL), and its AEMWE performance was evaluated without the use of any ionomer. At 1.0 M KOH, C4N, C5N, and TMA-based NiFe MOFs exhibited current densities of 9.35 A/cm2, 9.11 A/cm2, and 7.6 A/cm2, respectively. These current densities surpassed those of bare BDC-NiFe MOF and commercial IrO2 anode catalysts, which exhibited only 7.39 A/cm2 and 6.4 A/cm2, respectively. Consequently, we emphasize that the facilitation of local ionic transport could yield remarkable AEMWE performance, even in the absence of conventional polymeric ionomers.

Copper-doped strontium metal-organic framework: Dual-function active material for supercapacitor and oxygen evolution reaction

Bimetallic metal-organic frameworks (MOFs) have recently been a research hotspot for numerous energy applications because of the heightened synergistic impact between their elements. Nevertheless, MOFs' relatively low electrical conductivity and ability to mask active sites severely restrict their use. Herein, we synthesize a novel copper-doped strontium metal-organic framework (Cu-doped Sr MOF) material via a facile hydrothermal method. Interestingly, it demonstrates a notable energy storage performance with a specific capacity of 243.6 C g−1 (443 F g−1) compared to the undoped Sr MOF (81.3 C g−1 and 147.8 F g−1) at 1 A g−1. It also reveals long-term cycling stability (98.7 % over 10,000 GCD cycles) and fast ion diffusion. Moreover, an asymmetrical supercapacitor device assembled using Cu-doped Sr MOF as the positive electrode and AC as the negative electrode can provide an energy density of 19 Wh kg−1 and a power density of 801 W kg−1. The Cu-doped Sr MOF electrode exhibits a distinct overpotential of 398 mV compared to undoped Sr MOF (600 mV) at 10 mA cm−2, with a Tafel slope of 58 mV dec−1. The outstanding electrochemical performance and OER activity can be attributed to the synergistic effects between Cu and Sr in the MOF cluster. This study provides valuable insight into the doping strategy in the MOF cluster. Also, it opens new possibilities for designing alternative MOF electrodes and catalysts for commercial applications in supercapacitors and oxygen evolution reactions.

Constructing Metal-Organic Framework Films with Adjustable Electronic Properties on Hematite Photoanode for Boosting Photogenerated Carrier Transport.

Hematite (α-Fe2O3) has become a research hotspot in the field of photoelectrochemical water splitting (PEC-WS), but the low photogenerated carrier separation efficiency limits further application. The electronic structure regulation, such as element doping and organic functional groups with different electrical properties, is applied to alleviate the problems of poor electrical conductivity, interface defects, and band mismatch. Herein, α-Fe2O3 photoanodes are modified to regulate their electric structures and improve photogenerated carrier transport by the bimetallic metal-organic frameworks (MOFs), which are constructed with Fe/Ni and terephthalate (BDC) with 2-substitution of different organic functional groups (─H, ─Br, ─NO2 and ─NH2). The α-Fe2O3 photoanode loaded with FeNi-NH2BDC MOF catalyst exhibits the optimal photocurrent density (2mAcm-2) at 1.23VRHE, which is 2.33 times that of the pure α-Fe2O3 photoanode. The detailed PEC analyses demonstrate that the bimetallic synergistic effect between Fe and Ni can improve the conductivity and inhibit the photogenerated carrier recombination of α-Fe2O3 photoanodes. The ─NH2 group as an electron-donor group can effectively regulate the electron distribution and band structure of α-Fe2O3 photoanodes to prolong the lifetime of photogenerated holes, which facilitates photogenerated carrier transport and further enhances the PEC-WS performance of α-Fe2O3 photoanode.

Structural engineering of metal-organic framework catalysts for efficient conversion of glucose into 5-HydroxyMethylFurfural

The research on sustainable and efficient routes to produce valuable chemicals from renewable biomass has garnered considerable attention in recent years. Among these chemicals, 5-hydroxymethylfurfural (5-HMF) holds significant promise as a versatile platform molecule for various applications in the chemical industry. This study investigates the production of 5-HMF from glucose using zirconium-based metal-organic frameworks (Zr-MOFs) as environmentally friendly catalysts, an alternative to the traditional homogeneous catalysts. UiO-66 and its functionalized derivatives (e.g. UiO-66(NH2),UiO-66(COOH)2, and UiO-66(OH)2) were synthesized to study the effect of the functional groups on the dehydration reaction. The synthesized MOFs were fully characterized using powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), N2 adsorption-desorption, Infrared spectroscopy (IR), Pyridine-Fourier Transform Infrared spectroscopy (Py-FTIR), and scanning electron microscopy (SEM). The catalytic performance of the synthesized MOFswas evaluated for the dehydration of glucose to 5-HMF in DMSO and further optimized in other monophasic and biphasic systems. Results indicated that UiO-66(COOH)2 exhibited exceptional catalytic activity for the conversion of glucose to HMF, with a significantly higher HMF yield of 44 % compared to other reported MOF catalysts and to that of H2SO4, which yielded 35 % at a temperature of 140 °C and a 6 h reaction time. This is mainly attributed to the effect of the bifunctional active acid sites of the metal nodes and the functional group of the organic linker (free carboxylic groups), which acted as the main source of Lewis and Brønsted acid sites respectively, compared to UiO-66. Additionally, the results suggested that the catalyst with higher acid density, higher relative mesopority, and a moderate B/L ratio could enhance glucose dehydration regardless of the surface area. Furthermore, the catalyst demonstrated excellent reusability and stability, with a decrease of only 10 % after four reaction cycles. The recycled catalyst revealed no structural alterations in its framework. This study contributes to the growing body of research on Zr-based MOF as a stable and efficient catalyst for glucose valorization to produce 5-HMF under mild reaction conditions.

The catalytic activity of metal–organic frameworks (MOFs) and post-synthetic modified MOF towards depolymerisation of polycarbonate

Chemical recycling of polycarbonate (PC) recovers valuable chemicals like monomers but often requires catalysts for mild reaction conditions and high conversion rates. This study explores the use of metal–organic frameworks (MOFs) as catalysts for PC methanolysis. We investigated the catalytic activity of amine-containing MOFs, specifically ZIF-8, MAF-6, and UiO-66-NH2, which have basic active sites favouring PC depolymerisation. MOFs were characterised using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) analysis. We examined the effects of temperature, catalyst content, and time on PC recycling efficiency and also conducted post-synthetic modification (PSM) of MOF-5 to assess its catalytic performance in PC depolymerisation. Methanolysis yielded bisphenol A (BPA) and dimethyl carbonate (DMC), with conversion rates confirmed by nuclear magnetic resonance (NMR). MOF catalysts significantly enhanced conversion rates compared to reactions without catalysts, with ZIF-8 and MAF-6 achieving nearly 100% PC conversion. PSM of MOF-5 with ethylenediamine (ED) led to increased PC conversion. Additionally, the MOF-based catalysts were recovered and reused for up to three cycles.

High performance oxygen reduction and evolution reactions by graphitization of nickel –cobalt framework system

This study presents the successful synthesis of metal-organic frameworks (MOFs) via a simple one-pot method, followed by pyrolysis at 1000 °C to be used in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). A study utilizing various techniques, including field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and X-ray diffraction (XRD), investigated the properties of NiCo-MOF and its individual components before and after pyrolysis.The pristine MOFs exhibited limited electrochemical stability for both ORR and OER, while the pyrolyzed MOFs demonstrated a significant enhancement and excellent long-term stability in OER and ORR performance in alkaline media. Notably, the OER performance rivaled that of the benchmark IrO2 electrocatalyst, with similar onset potentials (1.48 V for IrO2, 1.52 V, 1.56 V, and 1.59 V for pyrolyzed NiCo-MOF, Co-MOF, and Ni-MOF, respectively). Furthermore, the pyrolyzed MOF catalysts displayed promising ORR activity in a 0.1 M KOH solution under O2 saturation, as evidenced by their onset potentials (around 0.615 V, 0.63 V, and 0.7 V vs. RHE) and favorable Tafel slopes (53, 84, and 154 mV dec⁻1, for graphitizated Ni-MOF, Co-MOF, and NiCo-MOF, respectively). These findings demonstrate the effectiveness of pyrolysis in engineering the MOF crystal structure for enhanced catalytic performance. This paves the way for further exploration of this synthesis method for the design of structurally optimized catalysts and applicable to a broad spectrum of energy technologies.

Activation of MOF Catalysts with Low Steric Hindrance via Undercoordination Chemistry for Efficient Polysulfide Conversion in Lithium–Sulfur Battery

AbstractLithium–sulfur (Li–S) batteries promise high theoretical energy density and cost‐effectiveness but grapple with challenges like the polysulfide shuttle effect and sluggish kinetics. Metal–organic framework (MOF) catalysts emerge as a leading solution, despite limited conductivity and high steric hindrance. This study employs undercoordination chemistry to modify Zn–Co bimetallic MOFs (D‐ZIF L), removing organic ligands from active centers. This process mitigates spatial hindrance, thereby promoting comprehensive contact between sulfur species and metal active centers, consequently enhancing the catalytic efficiency of MOFs. Moreover, undercoordination treatment of the metal active centers induces electron redistribution, augmenting electron density at the Fermi level of the metal elements, thereby ameliorating the intrinsic conductivity. Leveraging these advantages, fabricated Li–S batteries employing D‐ZIF L catalysts exhibited markedly mitigated shuttling effects and accelerated sulfur species conversion kinetics. Notably, a substantial reverse areal capacity of 5.0 mAh cm⁻2 is achieved after 100 cycles with an evaluated sulfur loading of 5.5 mg cm⁻2. Furthermore, a practical pouch cell demonstrated an initial capacity of 1.8 Ah at 85.8 mA with stable cycling for 50 cycles. This study underscores the potential of undercoordination chemistry in the development of highly conductive MOF catalysts with minimized steric hindrance, thereby advancing the prospects of Li–S battery technology.

Acetate-based ionic liquid immobilized Fe-MIL-101-NH2: A highly efficient heterogeneous catalyst for the conversion of CO2 into oxazolidinones with N-aryl epoxy amines

A novel acetate-based ionic liquid immobilized metal organic frameworks catalyst, Fe-MIL-101-N(Bnme2)OAc, was synthesized using a straightforward ion exchange strategy. Initially, Fe-MIL-101-N(Bnme2)Br was prepared by condensing a quaternary ammonium salt ionic liquid (N(BzBnme2)Br) with Fe-MIL-101-NH2. Subsequently, the Br- ions were exchanged with OAc- ions from potassium acetate to produce the desired catalyst. The morphology, structure and physicochemical properties of the catalyst were comprehensively characterized by XRD, SEM, FT-IR, DRS UV−vis, TGA, BET, and EA, which confirmed both the successful preparation of the catalyst and the integrity of the MOFs framework. The heterogeneous catalyst Fe-MIL-101-N(Bnme2)OAc demonstrated high activity in catalyzing the reaction of N-aryl epoxy amines with CO2 to form oxazolidinone compounds under optimal conditions (80 °C, 8 h, 1 mL of MeCN, 1.0 MPa CO2 and 5 mg catalyst), achieving a yield of up to 99 % with almost no production of the by-product cyclic carbonate. Moreover, this catalyst displayed excellent recyclability and extensive substrate applicability, maintaining its catalytic activity for at least five consecutive uses. Substrates with various substituents also produced the corresponding oxazolidinone products in high yields.

URJC-1: Stable and Efficient Catalyst for O-Arylation Cross-Coupling.

The design of metal-organic frameworks (MOFs) allows the definition of properties for their final application in small-scale heterogeneous catalysis. Incorporating various catalytic centers within a single structure can produce a synergistic effect, which is particularly intriguing for cross-coupling reactions. The URJC-1 material exhibits catalytic duality: the metal centers act as Lewis acid centers, while the nitrogen atoms of the organic ligand must behave as basic centers. The impact of reaction temperature, catalyst concentration, and basic agent concentration was evaluated. Several copper-based catalysts, including homogeneous and heterogeneous MOF catalysts with and without the presence of nitrogen atoms in the organic ligand, were assessed for their catalytic effect under optimal conditions. Among the catalysts tested, URJC-1 exhibited the highest catalytic activity, achieving complete conversion of 4-nitrobenzaldehyde with only 3% mol copper concentration in one hour. Furthermore, URJC-1 maintained its crystalline structure even after five reaction cycles, demonstrating remarkable stability in the reaction medium. The study also examined the impact of various substituents of the substrate alcohol on the reaction using URJC-1. The results showed that the reaction had high activity when activating substituents were present and for most cyclic alcohols rather than linear ones.

Highly Efficient Nitrogen Reduction to Ammonia through the Cooperation of Plasma and Porous Metal-Organic Framework Reactors with Confined Water.

While the ambient N2 reduction to ammonia (NH3) using H2O as hydrogen source (2N2+6H2O=4NH3+3O2) is known as a promising alternative to the Haber-Bosch process, the high bond energy of N≡N bond leads to the extremely low NH3 yield. Herein, we report a highly efficient catalytic system for ammonia synthesis using the low-temperature dielectric barrier discharge plasma to activate inert N2 molecules into the excited nitrogen species, which can efficiently react with the confined and concentrated H2O molecules in porous metal-organic framework (MOF) reactors with V3+, Cr3+, Mn3+, Fe3+, Co2+, Ni2+ and Cu2+ ions. Specially, the Fe-based catalyst MIL-100(Fe) causes a superhigh NH3 yield of 22.4 mmol g-1 h-1. The investigation of catalytic performance and systematic characterizations of MIL-100(Fe) during the plasma-driven catalytic reaction unveils that the in situ generated defective Fe-O clusters are the highly active sites and NH3 molecules indeed form inside the MIL-100(Fe) reactor. The theoretical calculation reveals that the porous MOF catalysts have different adsorption capacity for nitrogen species on different catalytic metal sites, where the optimal MIL-100(Fe) has the lowest energy barrier for the rate-limiting *NNH formation step, significantly enhancing efficiency of nitrogen fixation.