Layered Metal-organic Frameworks Research Articles

Asymmetric ionogel electrolyte with an ultrathin metal–organic framework layer for lithium dendrite inhibition in solid-state lithium-metal batteries

Solid-state electrolytes (SSEs) are used to prevent internal short circuits caused by the growth of lithium dendrites in solid-state lithium-metal batteries (SSLMBs). Ionogel electrolytes are new polymeric SSEs with outstanding processability, excellent flexibility, and superior ionic conductivity. Lithium-ion transport in ionogel electrolytes depends on ionic liquid (IL) content; however, increasing the IL content improves ionic conductivity but sharply decreases mechanical properties, thus limiting the ability to resist lithium dendrites. Thus, ionogel electrolytes must strike a balance between ionic conductivity and mechanical properties. Herein, we adopt a new strategy to suppress the growth of lithium dendrites by in situ polymerizing an ultrathin metal–organic framework (MOF) layer (9.8 μm) onto a highly ionic conductive ionogel electrolyte. The ionogel electrolyte provides an asymmetric SSE (ASSE) with a remarkable ionic conductivity of 4.8 × 10−4 S cm−1 (30 °C), whereas the ultrathin MOF layer regulates uniform dissolution/deposition of lithium and inhibits lithium dendrite growth, thereby increasing critical current density of the ASSE to 0.65 mA cm−2. An SSLMB assembled with the ASSE and LiFePO4 exhibits excellent performance and cycling stability, maintaining a specific capacity of 125.4 mAh g−1 after 500 cycles at 0.3C.

FO-SPR Model for Full-Spectrum Signal Analysis of Back-reflecting FO-SPR Sensors to Monitor MOF Deposition.

In this study, we explore the full-spectrum capabilities of fiber-optic surface plasmon resonance (FO-SPR) for analyzing heterogeneous samples with increased comprehensiveness. Our approach involves refining a literature-derived FO-SPR model to more precisely reflect experimental data obtained using a back-reflecting sensor configuration. Key enhancements in our model include adjustments to the thickness and permittivity of the gold SPR-active layer on the FO-SPR sensor as well as improvements to the angular distribution of light within the system. We apply this optimized model to the investigation of the deposition process of a metal-organic framework (MOF), specifically ZIF-8, using FO-SPR. By closely examining the temporal variations in the FO-SPR signal during MOF layer formation, we simultaneously determine the evolving thickness and refractive index (RI) of the MOF layer, offering a dual-parameter analysis. Our results demonstrate that a full-spectrum analysis of the FO-SPR signal can extract critical information from samples exhibiting radial heterogeneity. This advancement significantly enhances the quantitative assessment of various phenomena that alter the refractive index in the sensor's domain, such as adsorption and binding processes. This work thus represents a significant step forward in the field of FO-SPR sensor technology, promising broad applications in areas requiring the precise detection and analysis of complex samples.

Impact of Layer Stacking Manner on the Lithium-Ion-Battery Performance in Electrically Neutral Tetraoxolene-Bridged Iron(II) Hexagonal Layer Metal–Organic Frameworks

Impact of Layer Stacking Manner on the Lithium-Ion-Battery Performance in Electrically Neutral Tetraoxolene-Bridged Iron(II) Hexagonal Layer Metal–Organic Frameworks

Ratiometric emission of Tb(III)-functionalized Cd-based layered MOFs for portable visual detection of trace amounts of diquat in apples, potatoes and corn

Diquat (DQ) is a typical bipyridine herbicide widely used to control weeds in fields and orchards. The severe toxicity of diquat poses a serious threat to the environment and human health. Metal-organic frameworks (MOFs) have received widespread attention due to their unique physical and chemical properties and applications in the detection of toxic and harmful substances. In this work, a two-dimensional (2D) Tb(III) functionalized MOF Tb(III)@1 (1 = [Cd(HTATB)(bimb)]n·H2O (Cd-MOF), H3TATB = 4,4′,4″-triazine-2,4,6-tribenzoicacid, bimb = 1,4-bis((1H-imidazol-1-yl)methyl)benzene) has been prepared and characterized. Tb(III)@1 has excellent optical properties and high water and chemical stability. After the Tb(III) is fixed by the uncoordinated -COO- in the 1 framework, Tb(III)@1 emits the typical green fluorescence of the lanthanide ion Tb(III) through the “antenna effect”. It is worth noting that Tb(III)@1 can be used as a dual emission fluorescence chemical sensor for the ratio fluorescence detection of pesticide DQ, exhibiting a relatively low detection limit of 0.06 nM and a wide detection range of 0–50 nM. After the addition of DQ, a rapid color change of Tb(III)@1 fluorescence from green to blue was observed due to the combined effects of IFE, FRET and dynamic quenching. Therefore, a simple test paper box has been designed for direct on-site determination of pesticide DQ. In addition, the developed sensor has been successfully applied to the detection of DQ in real samples (fruits a Yin-Xia Sun and Bo-Tao Ji contributed equally to this work and should be considered co-first authors.nd vegetables) with satisfactory results. The results indicate that the probe developed in this study has broad application prospects in both real sample detection and actual on-site testing.

Structure optimization of ceramic-based metal−organic framework membrane for efficient desalination

To address global water pollution and crisis issue, wastewater recycling, seawater and brackish water desalination have been increasingly utilized to produce clean water. Ceramic membranes have been gaining widespread interest due to their unique physicochemical properties and high stability. Integrating nanoporous MOF (metal organic framework) with ceramic membranes could enable a rational design of ceramic-based MOF membranes with enhance sieving performance. Herein, we report an in-situ method to construct an inter-crystalline defect-free MOF layer on ZrO2 ceramic membranes for efficient desalination application. After optimizing synthesis parameters, an inter-crystalline defect-free and well-intergrown ceramic-based MOF membrane was obtained. The ceramic-based MOF membranes not only demonstrated a near-complete salt rejection, but also exhibited high water flux, which are superior to most of the reported zeolite and MOF membranes. In addition, the MOF membranes exhibited promising performance and structure stability even when exposed to harsh water environments. Our work introduces a protocol for the design of high-performance ceramic-based MOF membrane as a promising candidate for challenging desalination applications under different environments.

Poly(vinylidene fluoride)-based composite membranes with continuous metal–organic framework layer for high-performance separators of lithium-ion batteries

Lithium-ion batteries (LIBs) play a critical role in modern portable electronic devices, electric vehicles, and wearable electronics. However, the formation of lithium dendrites during cycling results in serious capacity loss and safety risks owing to the heterogeneous transport and deposition of Li+. In this work, we present a poly(vinylidene fluoride) (PVDF)-based composite membrane with a continuous metal–organic framework (MOF) layer as high-performance separators in LIBs. The PVDF membranes with uniform pore structures are prepared by using superspreading strategy, facilitating the growth of continuous and controllable MOF layer inside the membranes via a simple interfacial synthesis. The as prepared PVDF-MOF composite membranes display uniform and continuous subnanochannels with connected opened metal sites (OMS), which can generate a homogeneous transport of Li+. Taking advantages of the low impedance (∼2 Ω), high ionic conductivity (0.61 mS cm−1), and high stripping peak current (0.89 mA cm−2), the PVDF-MOF composite separators efficiently prevent the uneven deposition and the generation of lithium dendrites. Moreover, the PVDF-MOF-based LIBs showed a high capacity retention rate of 81.0 % after 250 cycles. This strategy paves a new avenue for MOF-based composite separator in LIBs.

Tunable Circularly Polarized Luminescence by Confining Dye Molecules within Chiral Layered Metal–Organic Framework

AbstractCircularly polarized luminescence (CPL) active materials have attracted widespread attention because of their potential applications. Nonetheless, it is still a great challenge to fabricate CPL materials with both high fluorescence quantum efficiency (Φ) and high luminescent asymmetry factor (glum). According to the unique structure characteristics of chiral layered metal–organic frameworks (CLMOFs), herein a novel strategy to construct high‐performance CPL materials, by utilizing the confinement effect of CLMOFs is developed. Conjugate dye molecules, such as fluorescent brighteners, fluorescein, and rhodamine B, which are readily subjected to aggregation‐caused quenching (ACQ) effect, are successfully intercalated into CLMOF matrix, affording blue, yellow–green, and red CPL, respectively. Both high Φ and glum values of up to 91% and 0.069 are obtained, owing to the distinct confinement effect of CLMOFs. After confining dye molecules within CLMOF, the ACQ effect is effectively inhibited, which is beneficial for fluorescence enhancement; simultaneously, the chirality transfer from CLMOF matrix to dyes by controlling their arrangement in the chiral confinement microenvironment, leading to the high glum values. Based on the full‐color and strong CPL, a multi‐dimensional code system is proposed. This work paves a new avenue to design and assemble CPL materials with high Φ and glum, which can be widely adopted.

Exfoliation of Metal-Organic Frameworks to Give 2D MOF Nanosheets for the Electrocatalytic Oxygen Evolution Reaction.

The structure and properties of materials are determined by a diverse range of chemical bond formation and breaking mechanisms, which greatly motivates the development of selectively controlling the chemical bonds in order to achieve materials with specific characteristics. Here, an orientational intervening bond-breaking strategy is demonstrated for synthesizing ultrathin metal-organic framework (MOF) nanosheets through balancing the process of thermal decomposition and liquid nitrogen exfoliation. In such approach, proper thermal treatment can weaken the interlayer bond while maintaining the stability of the intralayer bond in the layered MOFs. And the following liquid nitrogen treatment results in significant deformation and stress in the layered MOFs' structure due to the instant temperature drop and drastic expansion of liquid N2, leading to the curling, detachment, and separation of the MOF layers. The produced MOF nanosheets with five cycles of treatment are primarily composed of nanosheets that are less than 10 nm in thickness. The MOF nanosheets exhibit enhanced catalytic performance in oxygen evolution reactions owing to the ultrathin thickness without capping agents which provide improved charge transfer efficiency and dense exposed active sites. This strategy underscores the significance of orientational intervention in chemical bonds to engineer innovative materials.

Exfoliation of Metal–Organic Frameworks to Give 2D MOF Nanosheets for the Electrocatalytic Oxygen Evolution Reaction

AbstractThe structure and properties of materials are determined by a diverse range of chemical bond formation and breaking mechanisms, which greatly motivates the development of selectively controlling the chemical bonds in order to achieve materials with specific characteristics. Here, an orientational intervening bond‐breaking strategy is demonstrated for synthesizing ultrathin metal–organic framework (MOF) nanosheets through balancing the process of thermal decomposition and liquid nitrogen exfoliation. In such approach, proper thermal treatment can weaken the interlayer bond while maintaining the stability of the intralayer bond in the layered MOFs. And the following liquid nitrogen treatment results in significant deformation and stress in the layered MOFs’ structure due to the instant temperature drop and drastic expansion of liquid N2, leading to the curling, detachment, and separation of the MOF layers. The produced MOF nanosheets with five cycles of treatment are primarily composed of nanosheets that are less than 10 nm in thickness. The MOF nanosheets exhibit enhanced catalytic performance in oxygen evolution reactions owing to the ultrathin thickness without capping agents which provide improved charge transfer efficiency and dense exposed active sites. This strategy underscores the significance of orientational intervention in chemical bonds to engineer innovative materials.

Modification of titanium implants by bioactive and antibacterial zinc gallate metal organic framework

Bone diseases like rheumatoid arthritis or osteoporosis often lead to severe bone fractures requiring artificial implants. Titanium, especially its Ti6Al4V alloy, is favored for orthopedic and dental implants due to its exceptional properties. However, titanium implants face challenges like delayed osseointegration and bacterial susceptibility. Surface functionalization techniques, including antimicrobial coatings and drug delivery systems, aim to address these issues. Metal organic frameworks (MOFs), especially bio-MOFs, offer potential for implant modification due to their large surface area and biocompatible components. Here, we developed a MOF layer on titanium implants using gallic acid and Zn2+ ions to enhance antibacterial properties and bioactivity. The obtained materials were characterized using various research techniques. Using FT-IR microscopy, it was confirmed that the MOF is evenly distributed over the entire surface of the material. The MOF layer affects the hydrophilicity of the surface and the contact angle is approximately 60°. Additionally, tests for HAp growth, BSA adsorption and antibacterial performance were conducted. Our findings suggest that the MOF layer improves implant performance and biocompatibility by inducing HAp growth, enhancing protein sorption, and inhibiting microbial growth by about 20–40 % depending on the microorganism.

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.

Two-dimensional layered MOF nanosheets with multiple binding sites for selective detection and removal of Fe(III) ions

Heavy metal contamination has become an urgent global concern, posing a significant threat to our environment and health. Hence, it is critical to exploit functional materials for heavy metal ions sensing and elimination. However, the development of multifunctional materials that can simultaneously accomplish the selective detection and removal of the metal ions remains a significant challenge. In this work, a two-dimensional (2D) layered metal–organic framework (LMOF) functionalized with diverse binding sites has been utilized to concurrently detect and remove Fe3+ ions. The LMOF [Zn(hsb-2) (5-aipa)](HSB-W15) was rationally designed and constructed from the mixed ligands of hsb-2 (1,2-bis(4′-pyridylmethylamino)-ethane) and 5-aipa (5-aminoisophthate) under mild condition. In addition, the corresponding ultrathin nanosheets HSB-W15-NS were also obtained by adapting the instant in situ exfoliation (IISEM) method. Owing to the ultrathin nanosheet morphology and an abundance of active sites on the surface, HSB-W15-NS nanosheets can function as an effective fluorescent sensor to detect Fe3+ and Cr3+ ions. Exceptionally, HSB-W15-NS can also be used to selectively capture Fe3+ ions from water, with up to 93 % removal efficiency, and the adsorption equilibrium attained in 5 min. The sensing and adsorption processes were investigated based on kinetic model analysis, Fourier transform infrared spectroscopy, Raman spectrum analysis, density functional theory calculations, and control experiments. This work inspired the development of ultrathin 2D MOF nanosheets for applications in environmental protection.

Layered MOF supported on 2D delaminated MXene (Mo2Ti2C3) nanosheets boosted water splitting.

Metal organic frameworks (MOFs) have a porous structure, high surface area, and high charge transfer, and they have been regarded as model electrocatalysts. Optimization of the electrocatalytic activity of MOFs is challenging, and an effective strategy for this optimization is the construction of a well-defined interfacial bond bridge. In this work, an in situ approach of composite synthesis is reported for MOF (CoNiNH2BDC) with MXenes (Mo2Ti2C3), as the electrocatalytic properties of MOF can be greatly enhanced with the incorporation of the conductive material MXene. The prepared composite material was characterized thoroughly using XRD, XPS, FESEM, EDX, TEM, and BET. The synergistic effect of both components of this composite material resulted in enhanced conductivity and the number of active sites, which led to enhanced electrocatalytic performance. The CoNiNH2BDC MOF with different ratios of Mo2Ti2C3 MXene were synthesized, and the resulting materials were evaluated for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activities. It was observed that the MOFMX3 attained a 10 mA cm-2 current density at 1.44 V for OER and -0.037 V for HER (vs. RHE), and lower values of Tafel slopes of 44.8 mV dec-1 for OER and 45 mV dec-1 for HER in 0.1 M KOH were achieved. The higher double layer capacitance (C dl) values lead to high electrochemical surface area (ECSA) values. Lower Tafel slope values for MOFMX3 show that the presence of MXene nanosheets in the hybrid provides support to the layered and porous configuration of MOF, and the chances of the interaction of electrolyte to the catalytically active sites are significantly enhanced. This work highlights the idea of growing bimetallic MOFs on Mo2Ti2C3 MXene using an interdiffusion reaction strategy and opens up an avenue for designing highly electrocatalytic systems.

Tailoring van der Waals interactions in ultra-thin two dimensional metal-organic frameworks (MOFs) for photoconductive applications.

The diverse structural tunability of 2-dimensional π-stacked layered metal-organic frameworks (2D MOFs) enables the control of charge carrier mobility to achieve specific photoconductive characteristics. This study demonstrates the potential of various theoretical methodologies and frameworks in establishing a correlation between structure and functionality for such purposes. Through a focus on the archetypal Ni3(HITP)2 2D MOF, we examine the impact of quantum confinement and stacking fault defects on the absorption spectra using our recently-developed Frenkel-Holstein Hamiltonian. Specifically, the relationship between optical properties and number of layer units along the π-stacking direction is discussed. We employ Marcus rate theory to evaluate vertical carrier mobility subject to inter-layer proximity and different crystal packing which affect van der Waals interactions between layers. The insights presented in this research can inform the development of guidelines for enhancing photoconductive properties in 2D MOF nanosheets.

Synthesis of Metal-Organic Frameworks Zinc (II) with Optimum Slow Pyrolysis Process for Conductivity Performance

Metal-organic frameworks are one of the materials that currently have the potential as an anode material to replace graphite. It also has the advantages of large specific surface area, storage space and high gas absorption with high pore volume and good conductivity. The purpose of this study was to determine the optimum temperature for the synthesis of Metal-Organic Frameworks to obtain conductivity performance. Zinc nitrate hexahydrate and acetic acid were mixed in N, N-Dimthylformamide solvent at various temperatures of 250-650°C for 4 hours with a slow pyrolysis process and proceeded with precipitation. Solid Metal-Organic Frameworks formed were characterized using Scanning Electron Microscopy, X-ray diffraction, Fourier Transform Infra-Red, and IV-Meter. The crystal form is nanocubes of a layered metal-organic framework of Zinc (II) that penetrates each other in a hexagonal shape. The crystal contains zinc oxide with hydroxyl and carboxylic functional groups. Metal-organic synthesis occurs at an optimum reaction temperature of 450°C, showing high conductivity, with the fastest current increase, reaching a current of 3.82E-08 A at a voltage of 0.05 V.

Liquid exfoliation of a series of expanded layered Cu(II)-paddlewheel metal-organic frameworks to form nanosheets.

Ultrasonic liquid exfoliation provides a convenient route for converting layered materials into nanosheets. However, the relationship between the structure and morphology of the bulk materials and the properties of the resulting nanosheets remains poorly understood. In this work, we prepare an isoreticular series of layered metal-organic frameworks (MOFs) based on linear aromatic dicarboxylate derivatives (L1, L2, L3) with three different linker lengths (L3 > L2 > L1) and using copper(II) nitrate and acetate as metal ion sources. Liquid exfoliation of large crystals of all three MOFs [Cu2(L)2](solvent)2, synthesised from Cu(NO3)2, produced monolayer nanosheets with longer linkers leading to larger lateral dimensions. Exfoliation of smaller MOF crystals, formed using the copper(II) acetate salt under identical conditions, produced a much higher concentration of multi-layer nanosheets with smaller lateral dimensions. These results indicate that the initial crystal size plays an important role in determining both the lateral dimensions and the thicknesses of nanosheets. Such insights contribute to a deeper understanding of the design principles governing metal-organic framework nanosheets (MONs) and other two-dimensional materials.

Shear Stress‐Triggered Theranostic Nanoparticles for Piezoelectric‐Fenton‐Photodynamic Thrombolysis and Endogenous Thrombus Imaging

AbstractThrombus therapy is challenged by potential bleeding risk of thrombolytic agents, and external irradiation is usually needed in thrombus imaging. Herein, highly efficient theranostic platforms are designed for piezoelectric‐Fenton‐photodynamic thrombolysis and endogenous thrombus imaging in response to the elevated shear stress at the thrombus site. Piezoelectric tetragonal barium titanate (tBT) nanoparticles (NPs) are coated with Fe3+‐coordinated metal‐organic frameworks (MOFs), followed by inoculation of chlorin e6‐luminol conjugates and heparin absorption to obtain theranostic tBT@MOFCL/Hep NPs. Shear stress‐induced piezopotential on NPs accelerates Fe3+/Fe2+ transformation to deplete MOF layers, activates Fenton reaction and produces reactive oxidative species (ROS) for non‐pharmacological thrombolysis. In the meantime, the site‐specific ROS generation oxidizes luminol and the chemiluminescent resonance energy transfer with chlorin e6 generates red fluorescence for thrombus imaging without using external light irradiation. After intravenous injection into a carotid artery thrombosis model, the heparin‐mediated thrombus targeting yields 6.5‐fold higher luminescent intensity at the thrombus site. Thrombi in the carotid arteries are almost completely dissolved with integration of piezoelectric dynamic therapy, piezopotential‐enhanced Fenton reaction, and chemiluminescence‐excited photodynamic therapy, while causing no haematologic and histopathologic abnormality. This study demonstrates a concise strategy to generate shear stress‐responsive built‐in piezoelectric potentials, site‐specific non‐pharmacological thrombolysis, self‐illuminating, and stenosis degree‐adaptable thrombus imaging.

Optimizing Porous Metal-Organic Layers for Stable Zinc Anodes.

Aqueous zinc-ion batteries (ZIBs) have been considered as alternative stationary energy storage systems, but the dendrite and corrosion issues of Zn anodes hinder their practical applications. Here we report a series of two-dimensional (2D) metal-organic frameworks (MOFs) with Zr12 clusters, which act as artificial solid electrolyte interphase (SEI) layers to prevent dendrites and corrosion of Zn anodes. The Zr12-based 2D MOF layers were formed by incubating 3D layer-pillared Zr-MOFs in ZnSO4 aqueous electrolytes, which replaced the pillar ligands with terminal SO42-. Furthermore, the pore sizes of Zr12-based 2D MOF layers were systematically tuned, leading to optimized Zn2+ conduction properties and protective performance for Zn anodes. In contrast to the traditional 2D-MOFs with Zr6 clusters, Zr12-based 2D MOF layers as artificial SEI significantly reduced the polarization and increased the stability of Zn anodes in MOF@Zn||MOF@Zn symmetric cells and MOF@Zn||MnO2 full cells. In situ experiments and DFT computations reveal that the enhanced cell performance is attributed to the unique Zr12-based layered structure with intrinsic pores to allow fast Zn2+ diffusion, surface Zr-SO4 zincophilic sites to induce uniform Zn deposition, and inhibited hydrogen evolution by 2D MOF Zr12 layers.

Anisotropic Interface Successive Assembly for Bowl-Shaped Metal-Organic Framework Nanoreactors with Precisely Controllable Meso-/Microporous Nanodomains.

Colloidal metal-organic framework (MOF) nanoparticles, with tailored asymmetric nanoarchitectures and hierarchical meso-/microporosities, have significant implications in high-performance nanocatalysts, nanoencapsulation carriers, and intricate assembly architectures. However, the methodology that could achieve precise control over the anisotropic growth of asymmetric MOF particles with tailored distributions of meso- and microporous regions has not yet been established. In this study, we introduce a facile anisotropic interface successive assembly approach to synthesize asymmetric core-shell MOF (ZIF-67) nanobowls with worm-like mesopores in the core and intrinsic micropores in the shell. Our synthesis pathway relies on anisotropic nucleation of mesoporous MOF nanohemispheres on emulsion interfaces through the cooperative assembly of surfactants and MOF precursors. This is followed by the growth of microporous MOF layers on both interfaces of mesoporous cores and emulsion droplets, resulting in a hierarchically porous core-shell nanostructure. By utilizing this multi-interface-driven approach, we enable the creation of diverse geometries and distributions of mesopores and micropores in asymmetric MOF nanoarchitectures. The obtained bowl-like meso-/microporous core-shell ZIF-67 particles exhibit enhanced catalytic activity for CO2 cycloaddition, attributed to reactant accumulation within the bowl-like architecture, active site accessibility in the open mesoporous core, and improved structural stability. Overall, our study provides insights and inspiration for exploring the intricate asymmetric nanostructures of hierarchically porous MOFs with diverse potential applications.

Fabrication of an anionic layered metal-organic framework for the efficient removal of Sr2+

Efficient removal of radioactive 90Sr from solutions is of vital importance due to its radioactive nature and high mobility. Herein, a 2D anionic metal-organic framework (MOF) [Me2NH2][KZn(pydc)2(H2O)2]∙H2O (K-Zn-MOF; pydc = 2,6-pyridinedicarboxylic acid) was synthesized and characterized. The prepared K-Zn-MOF was in turn applied for the removal of Sr2+ ions and various experimental conditions including contact time, initial concentration, and temperatures were optimized. Experimental findings revealed that the adsorption of Sr2+ on K-Zn-MOF reached equilibrium within 60 min at room temperature with Re = 95.39%. K-Zn-MOF exhibited ultra-high adsorption capacity (878.3 mg g−1), remarkable affinity (Kd = 5.8 × 105 mL g−1) in solutions and super-high selectivity in the presence of interfering coexisting ions (Na+, K+, Mg2+, and Ca2+). Mechanistic investigation suggested that free exchangeable [Me2NH2]+ ions and strong interactions between uncoordinated oxygens from COO− groups with target ions significantly contributed to the rapid adsorption of Sr2+ ions.