Porous Metal-organic Frameworks Research Articles

Modular Synthesis of Templated Bimetallic Sites in Metal–Organic Framework Pores

Modular Synthesis of Templated Bimetallic Sites in Metal–Organic Framework Pores

Germ must be found: The HNT@RhB@MOF-Tb polychromatic fluorescent nanoprobe is applied for the visual detection of 2,6-dipicolinic acid

A polychromatic fluorescent nanoprobe based on natural halloysite nanotubes with fluorescent dyes and porous metal–organic frameworks co-loaded on the surface and inner wall of the nanotubes was constructed for the highly sensitive visual identification of the Bacillus anthracis biomarker 2,6-dichlorophenolic acid (DPA). The limit of detection for DPA was 11.27 nM, which is significantly lower than the spore-borne dose for anthrax infection (60 uM). The multi-color fluorescent probe showed potential for rapid, accurate, and highly selective detection of Bacillus anthracis markers in actual samples. Besides, a portable fluorescence detection platform was developed in combination with a smartphone color scanning APP to simplify the detection process and realize real-time semi-quantitative analysis.

An amino acid-functionalized coordination polymer of Cd(II) as a fluorescent probe detecting Cu(II) ion

Cd(II) complex 1, namely {[Cd(HL)]·CH3OH}n was design as a new fluorescence probe for measuring concentration of Cu2+ ion in aqueous solution. Complex 1 is a 3,6-connected double-layered porous metal–organic framework, which was synthesized by optimizing the ratio of Cd(OH)2 and a new ligand 4'-(((1-carboxyethyl)amino)methyl)-[1,1′-biphenyl]-3,5-dicarboxylic acid (H3L) under solvothermal conditions. It not only had good thermal and solvent stabilities, but also displayed a strong solid-state fluorescence centered at 375 nm with a moderate quantum yield of 37.12% under excitation at 275 nm. More importantly, its fluorescence could be obviously quenched by the addition of Cu2+ ion. The fluorescence quenching may be caused by the weak coordination interaction between Cu2+ and the uncoordinated imino N in ligand (HL)2–, as well as the slightly competitive absorption of excitation light by Cu2+. In the low concentration range of Cu2+ ion, the fluorescence quenching efficiency of complex 1 is closely related to the concentration of Cu2+ ion, and the relationship between fluorescence quenching efficiency and the concentration of added Cu2+ ion could be well fitted by Stern-Volmer equation with KSV being 1.589 × 104 M−1 and the detection limit for Cu2+ ion being 5.7 μM. Our case may provide potential applications for the detection of Cu2+ ion in daily domestic water.

Eye-Readable and Wearable Colorimetric Sensor Arrays for In Situ Monitoring of Volatile Organic Compounds.

Wearable sensors utilize changes in color as a response to physiological stimuli, making them easily recognizable by the naked eye. These colorimetric wearable sensors offer benefits such as easy readability, rapid responsiveness, cost-effectiveness, and straightforward manufacturing techniques. However, their applications in detecting volatile organic compounds (VOCs) in situ have been limited due to the low concentration of complex VOCs and complicated external interferences. Aiming to address these challenges, we introduced readable and wearable colorimetric sensing arrays with a microchannel structure and highly gas-sensitive materials for in situ detection of complex VOCs. The highly gas-sensitive materials were designed by loading gas-sensitive dyes into the porous metal-organic frameworks and further depositing the composites on the electrospun nanofiber membrane. The colorimetric sensor arrays were fabricated using various gas-sensitive composites, including eight dye/MOF composites that respond to various VOCs and two Pd2+/dye/MOF composites that respond to ethylene. This enables the specific recognition of multiple characteristic VOCs. A microfluidic channel made of polydimethylsiloxane (PDMS) was integrated with different colorimetric elements to create a wearable sensor array. It was attached to the surface of fruits to collect and monitor VOCs using the DenseNet classification method. As a proof of concept, we demonstrated the feasibility of the wearable sensing system in monitoring the ripening process of fruits by continuously measuring the VOC emissions from the skin of the fruit.

A novel magnetic Fe, N co-doped Ce-MOFs derived carbon as a peroxymonosulfate activator for the degradation of tetracycline hydrochloride: Performance and activation mechanism

The activation of peroxymonosulfate (PMS) using metal-organic frameworks (MOFs) has garnered significant interest in the field of wastewater treatment. However, the environmental challenges associated with traditional methods for synthesizing MOFs precursors, such as the requirement for high temperatures and pressures, remain. Furthermore, the catalytic performance and stability of mono-metallic materials are areas needing enhancement. This work successfully synthesized a novel magnetic Fe-Ce bimetallic N-doped porous MOF material (Fe/Ce@5MNC). The optimized Fe/Ce@5MNC exhibited a higher specific surface area and a more extensive pore structure, as verified by various characterization techniques. Moreover, the synthesis process of the precursor is simpler, energy-saving, and relatively environmentally friendly. Notably, the synergistic effect between Fe and Ce, coupled with the presence of multiple active sites such as FeNx and graphite N, enabled Fe/Ce@5MNC to decompose 86.4 % of TCH within 30 min, marking a 31.4 % increase over Ce@NC. After four cycles, the catalyst maintained good surface stability, with the degradation efficiency remaining at 67.7 %. Quenching and electron paramagnetic resonance (EPR) experiments confirmed that the main degradation mechanisms are singlet oxygen (1O2) generation and electron transfer. This study presents a new method for synthesizing efficient Fe, N co-doped magnetic bimetallic PMS activators and designing carbon catalysts for deep oxidation.

Layer by Layer Spraying Fabrication of Aggregation-Induced Emission Metal-Organic Frameworks Thin Film.

The development of new metal-organic frameworks (MOFs) thin films is important for expanding their functions and applications. Herein, we first report a new kind of MOF thin film by using aggregation-induced emission (AIE) dicarboxyl ligand through a liquid-phase epitaxial (LPE) layer-by-layer (LBL) spraying method (named AIE surface-coordinated metal-organic frameworks thin film, AIE-SURMOF). The obtained AIE-SURMOF Zn4O(TPE)3 (ZnTPE) has highly growth orientation and homogeneous thin film, showing strong fluorescent property. Furthermore, by loading chiral guest in the MOF pore, the formed chiral encapsulated AIE-SURMOF can clearly indicate obvious circularly polarized luminescence performance with glum of 0.01. This study provides new MOF thin film and new strategy for expanding function and application of MOF materials.

Renewal of electrical energy by green hydrogen using a metal organic framework with Fe3O4 cluster

Recently, metal-–organic frameworks (MOFs) with high porosity have drawn extensive attention in water splitting. The present study reports the synthesis of a porous Fe-based MOF by a modified precursor made of magnetite (Fe3O4). Subsequently, a series of undoped and lanthanide -doped (MOFs) are prepared using the solvothermal method. The synthesis provided a high surface area with a high specific surface and pore volume. The synthesized electrocatalyst with a high surface area is demonstrated as an excellent electrocatalyst for the hydrogen evolution reaction(HER) investigated in acidic media. The electrochemical results demonstrated low Tafel slopes (81 and 166 mV dec–−1), high exchange current, high ssurface area (Cdl) (148.29 and 150.57 mV), and high stability for Au/MIL-53 (Fe)/Gd-Fe3O4 and glassy carbon electrode GCE/MIL-53 (Fe)/La-Fe3O4. The high activity is attributed to the large surface area of the synthesized Fe/ Fe3O4-based MOF, which is porous and magnetic. The effect of base metal on catalyst performance was discussed. Through the unification of two catalytically active metals as lanthanide, a new opportunity opens up for the development of synergistic systems in multiple applications.

Direct observation of tunable thermal conductance at solid/porous crystalline solid interfaces induced by water adsorbates

Improving interfacial thermal transport is crucial for heat dissipation in devices with interfaces, such as electronics, buildings, and solar panels. Here, we design a strategy by utilizing the water adsorption-desorption process in porous metal-organic frameworks (MOFs) to tune the interfacial heat transfer, which could benefit their potential in cooling or heat dissipation applications. We observe a changeable thermal conductance across the solid/porous MOF interfaces owing to the dense water channel formed by the adsorbed water molecules in MOFs. Our experimental and/or modeling results show that the interfacial thermal conductance of Au/Cu3(BTC)2, Au/Zr6O4(OH)4(BDC)6 and Au/MOF-505 heterointerfaces is increased up to 7.1, 1.7 and 3.1 folds by this strategy, respectively, where Cu3(BTC)2 is referred to as HKUST-1 and Zr6O4(OH)4(BDC)6 is referred to as UiO-66. Our molecular dynamics simulations further show that the surface tension of Au layer will cause the adsorbed water molecules in MOFs to gather at the interfacial region. The dense water channel formed at the interfacial region can activate the high-frequency lattice vibrations and act as an additional thermal pathway, and then enhance heat transfer across the interfaces significantly. Our findings revealed the underlying mechanisms for tailoring thermal transport at the solid/porous MOF heterointerfaces by water adsorbates, which could motivate and benefit the new cooling system design based on MOFs.

Hydrogen-Bonded Metal-Organic Framework Nanosheet as a Proton Conducting Membrane for an H2/O2 Fuel Cell.

Proton-conducting metal-organic frameworks (MOFs) have attracted attention as potential electrolytes for fuel cells. However, research progress in utilizing MOFs as electrolytes for fuel cells has been limited, mainly due to challenges associated with issues such as the fabrication of MOF membranes, and hydrogen crossover through the MOF's pores. Here, proton conductivity and fuel cell performance of a self-standing membrane prepared from of a bismuth subgallateMOF nanosheets with non-porous structure are reported. The fabricated MOF nanosheet membrane with no binding agent exhibits structural anisotropy. The proton conductivity in the membrane thickness direction (4.4×10-3Scm-1) at 90°C and RH 100% is observed to be higher than that in the in-plane direction of the membrane (3.3×10-5Scm-1). The open circuit voltage (OCV) of a fuel cell with ≈120µm proton conducting membrane is 1.0V. The non-porous nature of the MOF nanosheets contributes to the relatively high OCV. A fuel cell using ≈40µm membrane as proton conducting electrolyte records a maximum of 25mWcm-2 power density and a maximum of 109mAcm-2 current density with 0.91V OCV at 80°C in humid conditions.

Rational Design of a Necklace-like ZIF-67/Poly(vinylidene fluoride) Electrospun Nanofiber Hybrid Membrane for Simultaneous Removal of PM0.3 and SO2.

Growing concerns over poor air quality, especially in urban and industrial regions, have led to increased global demands for advanced air-purification technologies. However, the stability and airborne pollutant control abilities of the available air-purification materials under diverse environmental conditions are limited. Thus, the advanced development of filtration materials that can effectively control different types of pollutants, such as particulate matter (PM) and gaseous pollutants, simultaneously has attracted attention. The zeolitic imidazolate framework (ZIF), a type of porous metal-organic framework (MOF), is a promising material for capturing weakly acidic toxic gases such as SO2 owing to its excellent adsorption performance and high thermal and chemical stability. In this study, we successfully developed an ultrastable necklace-like multifunctional hybrid membrane via the cetyltrimethylammonium bromide-assisted in situ growth of zeolitic imidazolate framework (ZIF)-67 crystals on electrospun Co2+-doped poly(vinylidene fluoride) nanofibers (70 nm) that can be used in different moisture environments to achieve sustainable air-filtration performance. The hybrid nanocomposite membrane demonstrated excellent performance for the simultaneous control of intractable fine PM0.3 (filtration efficiency, 99.461%) and SO2 (adsorption capacity, 1476.5 mg g-1) under different humidity conditions. This study contributes to the optimal synergistic integration of the advanced metal-organic framework (MOF)-nanofiber nanocomposite membranes and can guide the rational design and conceptualization of a facile and novel membrane for various applications in the environmental science and energy fields.

Determining Surface Areas and Pore Volumes of Metal-Organic Frameworks.

The surface area and pore volume of a metal-organic framework (MOF) can provide insight into its structure and potential applications. Both parameters are commonly determined using the data from nitrogen sorption experiments; commercial instruments to perform these measurements are also widely available. These instruments will calculate structural parameters, but it is essential to understand how to select input data and when calculation methods apply to the sample MOF. This article outlines the use of the Brunauer-Emmett-Teller (BET) method and Barrett-Joyner-Halenda (BJH) method for the calculation of surface area and pore volume, respectively. Example calculations are performed on the representative MOF UiO-66. Although widely applicable to MOFs, sample materials and adsorption data must meet certain criteria for the calculated results to be considered accurate, in addition to proper sample preparation. The assumptions and limitations of these methods are also discussed, along with alternative and complementary techniques for the MOF pore space characterization.

Design of sonochemical assisted synthesis of Zr-MOF/g-C3N4-modified electrode for ultrasensitive detection of antipsychotic drug chlorpromazine from biological samples.

Therapid fabrication is describedof binary electrocatalyst based on a highly porous metal-organic framework with zirconium metal core (Zr-MOF) decorated over the graphitic carbon nitride (g-C3N4) nanosheets via facile ultrasonication method. It is used for the robust determination of antipsychotic drug chlorpromazine (CLP) from environmental samples. The electrochemical behaviour of 2D Zr-MOF@g-C3N4 was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies. The crystalline and porous nature of the composite was characterized by XRD and SEM analysis. The functional groups and surface characteristics were investigated by FT-IR, Raman and XPS. The major electrochemical properties of the Zr-MOF@g-C3N4 composite towards CLP detection were analyzed by CV, chronocoulometric (CC), chronoamperometric (CA) and differential pulse voltammetry (DPV) techniques. The composite exhibits a low detection limit (LOD) of 2.45nM with a linear range of 0.02 to 2.99µM and attractive sensitivity for CLP. The sensor system shows higher selectivity towards the possible interferences of CLP drug and exhibits betterrepeatability and stability. Finally, the fabricated sensor system shows a high recovery range varying from 96.2 to 98.9% towards the real samples. The proposed electrochemical probe might be a promising alternative to the prevailing diagnostic tools for the detection of CLP.

Ligand Mediated Assembly of CdS Colloids in 3D Porous Metal–Organic Framework Derived Scaffold with Multi‐Sites Heterojunctions for Efficient CO2 Photoreduction

AbstractThe inclusion of colloidal particles into 3D porous constructs to realize heterostructure ensembles enhances surface interactions and energy transfer that can transform the catalytic properties of conventional catalysts. However, assembling hydrophobic colloidal nanoparticles within hydrophilic 3D porous matrices to create tailored heterostructures and catalytic properties is particularly challenging. Here, a modified ligand grafting method is presented to spontaneously assemble CdS inorganic colloidal quantum dots within a metal‐organic framework (MOF) derived porous framework for efficient photocatalytic CO2 reduction. The grafted long chain molecular ligands effectively suppress phase separation and endow a molecular‐recognition effect to form ordered assembly microstructures. The proof‐of‐concept assembly of CdS and Prussian blue analogues (PBA) derived Co3O4 facilitates a high density of heterojunctions formation, improving charge transfer and extended lifetimes of photo‐induced electrons. Consequently, CdS/Co3O4 assembly exhibits exceptionally active and stable photocatalytic CO2 reduction activity, with a CO production rate of 73.9 µmol g−1 h−1 and CO selectivity of 98.9%. Importantly, the ligand grafting method can be generalized to achieve spontaneous assembly of quantum dots within various metal organic framework derived porous scaffolds. This work provides a rational strategy for precise self‐assembly of colloidal nanoparticles within porous microstructures, allowing tailored heterointerfaces for functional materials and applications.

ZIF-8@CsPbBr3 Nanocrystals Formed by Conversion of Pb to CsPbBr3 in Bimetallic MOFs for Enhanced Photocatalytic CO2 Reduction.

Perovskite nanocrystals are embedded into metal-organic frameworks (MOFs) to create composites with high light absorption coefficients, tunable electronic properties, high specific surface area, and metal atom tunability for enhanced photocatalytic carban dioxide (CO2) reduction. However, existing perovskite-MOF structures with a large particle size are achieved based on Pb source adsorption into the pores of MOFs, which can significantly break down the porous structure, thereby resulting in a decreased specific surface area and impacting CO2 adsorption. Herein, a novel perovskite-MOF structure based on the synthesis of bimetallic Pb-containing MOFs and post-processing to convert Pb to CsPbBr3 nanocrystals (NCs) is proposed. It is discovered that the additional Pb is not introduced by adsorption, but instead engages in coordination and generates Pb-N. The produced ZIF-8@CsPbBr3 NCs are ≈40nm and have an ultra-high specific surface area of 1325.08 m2g-1, and excellent photovoltaic characteristics, which are beneficial for photocatalytic CO2 reduction. The electronic conversion rate of composites is 450mol g-1h-1, which is more than three times that of pure perovskites. Additionally, the superior reduction capacity is sustained after undergoing four cycles. Density Functional Thoery (DFT) simulations are used to explore the 3D charge density at the ZIF-8@CsPbBr3 NCs interface to better understand the electrical structure.

Highly Porous Metal-Organic Framework Entrapped by Cobalt Telluride-Manganese Telluride as an Efficient Bifunctional Electrocatalyst.

The electrochemical conversion of oxygen holds great promise in the development of sustainable energy for various applications, such as water electrolysis, regenerative fuel cells, and rechargeable metal-air batteries. Oxygen electrocatalysts are needed that are both highly efficient and affordable, since they can serve as alternatives to costly precious-metal-based catalysts. This aspect is particularly significant for their practical implementation on a large scale in the future. Herein, highly porous polyhedron-entrapped metal-organic framework (MOF)-assisted CoTe2/MnTe2 heterostructure one-dimensional nanorods were initially synthesized using a simple hydrothermal strategy and then transformed into ZIF-67 followed by tellurization which was used as a bifunctional electrocatalyst for both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The designed MOF CoTe2/MnTe2 nanorod electrocatalyst exhibited superior activity for both OER (η = 220 mV@ 10 mA cm-2) and ORR (E1/2 = 0.81 V vs RHE) and outstanding stability. The exceptional achievement could be primarily credited to the porous structure, interconnected designs, and deliberately created deficiencies that enhanced the electrocatalytic activity for the OER/ORR. This improvement was predominantly due to the enhanced electrochemical surface area and charge transfer inherent in the materials. Therefore, this simple and cost-effective method can be used to produce highly active bifunctional oxygen electrocatalysts.

Constructing light-insensitive Ag(I) sites by in situ integration of nanoheaters for efficient adsorptive desulfurization

The π-complexation between Ag(I) and thiophene sulfides is considered as one of the key factors to selectively remove thiophenic compounds, but its application is very limited due to the instability of Ag(I) under light as well as the energy-intensive regeneration. In this study, stable and photothermal Ag(I)/Ag(0) composite sites are constructed in metal-organic frameworks (MOFs) and act as target-specific adsorption sites for the uptake of thiophenic compounds. Partial Ag(0) nanoparticles that were in situ introduced in MOF pores are oxidized to Ag(I). As a result, Ag(I) becomes light-insensitive because the light-induced electron of Ag(I) can be transferred to the integrated Ag(0) nanoparticles, protecting Ag(I) from reduction. Furthermore, Ag(0) nanoparticles are photothermal due to the localized surface plasmon resonance, thus can precisely heat Ag(I) for desorption by converting visible light to energy. This work provides a new avenue to stabilize Ag(I) and efficiently regenerate adsorbents.

Iodine Adsorption-Desorption-Induced Structural Transformation and Improved Ag+ Turn-On Luminescent Sensing Performance of a Nonporous Eu(III) Metal-Organic Framework.

Posttreatment of pristine metal-organic frameworks (MOFs) with suitable vapor may be an effective way to regulate their structures and properties but has been less explored. Herein, we report an interesting example in which a crystalline nonporous Eu(III)-MOF was transferred to a porous amorphous MOF (aMOF) via iodine vapor adsorption-desorption posttreatment, and the resulting aMOF showed improved turn-on sensing properties with respect to Ag+ ions. The crystalline Eu-MOF, namely, Eu-IPDA, was assembled from Eu(III) and 4,4'-{4-[4-(1H-imidazol-1-yl)phenyl]pyridine-2,6-diyl}dibenzoic acid (H2IPDA) and exhibited a two-dimensional (2D) coordination network based on one-dimensional secondary building blocks. The close packing of the 2D networks gives rise to a three-dimensional supramolecular framework without any significant pores. Interestingly, the nonporous Eu-IPDA could absorb iodine molecules when Eu-IPDA crystals were placed in iodine vapor at 85 °C, and the adsorption capacity was 1.90 g/g, which is comparable to those of many MOFs with large BET surfaces. The adsorption of iodine is attributed to the strong interactions among the iodine molecule, the carboxy group, and the N-containing group and leads to the amorphization of the framework. After immersion of the iodine-loaded Eu-IPDA in EtOH, approximately 89.7% of the iodine was removed, resulting in a porous amorphous MOF, denoted as a-Eu-IPDA. In addition, the remaining iodine in the a-Eu-IPDA framework causes strong luminescent quenching in the fluorescence emission region of the Eu(III) center when compared with that in Eu-IPDA. The luminescence intensity of a-Eu-IPDA in water suspensions was significantly enhanced when Ag+ ions were added, with a detection limit of 4.76 × 10-6 M, which is 1000 times that of pristine Eu-IPDA. It also showed strong anti-interference ability over many common competitive metal ions and has the potential to sense Ag+ in natural water bodies and traditional Chinese medicine preparations. A mechanistic study showed that the interactions between Ag+ and the absorbed iodine, the carboxylate group, and the N atoms all contribute to the sensing performance of a-Eu-IPDA.

Improving the Separation of CO2/N2 Using Impregnation of a Deep Eutectic Solvent on a Porous MOF.

As the partial pressure of CO2 in flue gas is 0.1-0.2 bar, CO2 capture at a low pressure needs more attention. Under low pressure conditions, the functional metal-organic framework (MOF) is powerful for CO2 capture. One of the effective methods to increase the absorption capacity of the MOF is impregnation with deep eutectic solvents. In this research, NH2-MIL101(Cr) is impregnated with a deep eutectic solvent of choline chloride:urea (DES ChCl:urea) to enhance the adsorption capacity. The CO2 and N2 adsorption capacity of NH2-MIL101(Cr) and DES/NH2-MIL101(Cr) was investigated at temperatures of 288.15-303.15 K and pressures up to 1 bar. The obtained results indicate that the adsorption capacity of the MOF increases by 1.7 and 3 times with the impregnated DES for CO2 and N2, respectively. Nevertheless, the pore volume of the MOF decreased after impregnation, but the adsorption capacity of the MOF increased due to the interaction of the adsorbate with the confined DES in pores. The contribution of the impregnated DES to adsorption capacity is explained according to Henry's law. Also, high heats of adsorption are attributed to the strong interaction between modified NH2-MIL101(Cr) and CO2. Also, the sample was refined at 298 K and vacuum and was reused without considerable reduction of the CO2 capture capacity after 6 times. Moreover, the impregnation of ChCl:urea into NH2-MIL101(Cr) nanostructures was studied using density functional theory-based approaches.

Hierarchical synthesis of binary ZnO@MWCNTs heterogeneous photocatalyst derived from porous Zn metal organic framework (MOF) template: Study on the effective photodegradation of Congo red (CR) dye

This study presents the synthesis of a heterogeneous ZnO@MWCNTs photocatalyst through a solvothermal method, employing a Zn-metal organic framework (MOF) template. The resulting nanocomposite showcases ZnO nanorods integrated with MWCNTs, forming a material characterized by nanosized building blocks, a substantial specific surface area, robust pore structure, and uniform morphology. A comprehensive XRD characterization reveals crystalline ZnO nanorods proficiently loaded onto the MWCNTs surface, forming a cohesive nano-composite. The inclusion of MWCNTs influences crystal growth, reducing crystallite size and altering optical absorption due to surface Plasmon resonance. This leads to a higher concentration of surface hydroxyl groups in the ZnO framework. Additionally, MWCNTs act as electron sinks, significantly reducing ZnO photooxidation and enhancing overall photostability in the composite. The photocatalytic efficacy of the composite in Congo Red (CR) degradation is impressive, achieving 92% degradation within 90 min of UV light exposure. A proposed photocatalytic mechanism elucidates the heightened performance of the synthesized photocatalysts. Notably, the MOF-derived ZnO@MWCNTs exhibited superior dye adsorption capacity compared to alternative adsorbents. This work underscores the immense potential of the ZnO@MWCNTs nanocomposite as a highly efficient photocatalyst for environmental remediation, offering significant advancements in dye degradation and wastewater treatment technologies.

An ultrathin and crack‐free metal‐organic framework film for effective polysulfide inhibition in lithium–sulfur batteries

AbstractDue to their extensive microporous structure, metal‐organic frameworks (MOFs) find widespread application in constructing modification layers, functioning as ion sieves. However, the modification layers prepared by existing methods feature gaps between MOFs that are noticeably larger than the inherent MOF pore dimensions. Polysulfides and lithium ions unavoidably permeate through these gaps, hindering the full exploitation of the structural advantages. Herein, an ultrathin (20 nm) and crack‐free MOF film is formed on the separator by atomic layer deposition for the first time. Based on the separator, the mechanism of different MOF layers has been verified by phase field simulation and in situ Raman spectroscopy. The results accurately prove that the MOF particle layer can relieve the shuttle of polysulfides, but it does not have the effect of homogenizing lithium ions. Only the ultrathin and crack‐free MOF film with proper pore size can act as the ion sieve for both polysulfides and lithium ions. As a result, under the test condition of 2 mA cm−2–2 mAh cm−2, the overpotential of the Li/Li symmetric battery is only 18 mV after 2500 h. The capacity retention rate of the lithium–sulfur battery is 95.6% after 500 cycles and 80% after 1000 cycles at 2 C.