Search

ReO4– as a hazardous waste severely threatens environmental safety and human health. The high-efficiency adsorbent for the removal of ReO4– is of immense interest but still faces challenges. Herein, we established cationic metal–organic framework nanoparticles by an amino protonation strategy. Based on a facile and green method, we first introduced dense amino groups (6.59 mmol/g) in UiO-66 in situ to prepare UiO-66-(NH2)2, during which acetic acid as a modulator was applied to construct defects. Subsequently, UiO-66-(NH2)2 was acidified to the cationic UiO-66-(NH3+Cl–)2. Notably, this cationic adsorbent exhibits a high adsorption capacity of 590.2 mg g–1 and a short adsorption equilibrium time of 240 min for ReO4–. Besides, the excellent chemical stability and reusability endow UiO-66-(NH3+Cl–)2 with promising potential in practical applications. Experimental characterization and density functional theory (DFT) calculations suggest that the electrostatic interaction, ion exchange, and coordination interaction jointly contribute to the effective removal of ReO4–. Thus, this work provides a highly efficient cationic metal–organic framework nanoparticle for ReO4– removal and, importantly, proposes a feasible strategy for constructing cationic adsorbents. [ABSTRACT FROM AUTHOR]

The increasing demand for sustainable and efficient catalytic processes has driven the development of advanced nanoreactors. In this study, we present a sophisticated Metal–organic framework (MOF)-template-mediated approach to synthesize yolk–shell Co-CN@SiO2 nanoreactors, where Co nanoparticles were supported on carbon nitride (C–N) nanosheets as the core encapsulated within a nanoporous SiO2 shell. This yolk–shell structure with confined cavities can provide a high surface area and overcome challenges such as Co nanoparticle sintering and mass transport limitations, resulting in superior catalytic performance. Remarkably, these nanoreactors achieved a 99% yield of benzyl alcohol from benzaldehyde hydrogenation under base-free conditions. Moreover, the influence of calcination temperatures on the structural evolution of the Co-based silica nanoreactors was explored, revealing the critical role of synergistic interaction between C–N and Co nanoparticles in boosting catalytic activity. Density functional theory calculations were conducted to investigate the adsorption energies of reacting species on the catalyst, providing mechanistic insights into the enhanced hydrogenation activity of the Co-CN@SiO2. This work offers valuable insights into the rational design of advanced nanoreactors for various catalytic applications, particularly in the field of green chemistry and sustainable synthesis. [ABSTRACT FROM AUTHOR]

Conventional metal oxide semiconductor (MOS) gas sensors have an inherent disadvantage of high operating temperatures and low sensitivity to weakly polarized gases, such as methane. This study mainly focuses on developing specialized MOS-based gas sensors for the highly sensitive detection of methane. Therefore, we designed and prepared Co3O4-based nanocomposites of La-CoOx/N/C via the pyrolysis of a La-doped zeolitic imidazolate framework (ZIF-67) hydrothermally grown on carbon black (CB) nanospheres. The resulting La-CoOx/N/C material is dominated by hollow nanospheres, owing to CB pyrolysis. In the as-formed nanocomposite, the dispersed La2O3 acts as a "fence" to prevent the agglomeration of Co3O4 nanoparticles and form rich heterojunctions. Meanwhile, N-coordinated carbon (N/C) acts as an anchor for La-CoOx attachment, which further improves the dispersion of the composite oxides and enhances their adsorption capacity for methane molecules. Consequently, the La-CoOx/N/C sensor demonstrated a response of 1.25 with 4/5 s recovery/response times for 600 ppm of methane at a relatively low temperature (130 °C). Furthermore, a methane-sensing mechanism is demonstrated based on heterostructure effects and first-principles calculations. The proposed La-CoOx/N/C gas sensor is a device that exhibits excellent methane sensing performance at low temperatures without requiring precious metals. [ABSTRACT FROM AUTHOR]

In recent years, antitumor strategies based on reactive oxygen species (ROS) have received extensive attention but are limited due to the low efficiency of ROS production and unsatisfactory free radical toxicity. In this work, Na2S2O8@Co-metal–organic framework (ZIF-67) @glucose oxidase (NZG) NPs were prepared to provide highly toxic ROS including •SO4– and •OH and used for the treatment of breast cancer. When NZG NPs entered the tumor tissue, the Co-based metal–organic framework (ZIF-67) was responsively broken in the acidic microenvironment, and the released GOx further promoted the generation of gluconic acid and H2O2, thus accelerating ZIF-67 cleavage and Na2S2O8 release under lower pH. The highly toxic sulfate radical (•SO4–) converted from S2O82– could further combine with H2O to produce •OH, thereby enriching the ROS species at the tumor site. The combination of •SO4– and •OH not only effectively induced the apoptosis of breast cancer cells but also reversed the immunosuppressive microenvironment at the tumor site. In summary, as a novel highly toxic ROS nanogenerator, NZG NPs provide efficient chemokinetic therapy and immune activation to promote tumor tissue ablation, providing a strategy for the development of antitumor ROS generators. [ABSTRACT FROM AUTHOR]

The primary challenges for nanozyme-mediated tumor catalytic therapy are the insufficient catalytic activity of nanozymes and inadequate endogenous hydrogen peroxide (H2O2) levels in the tumor microenvironment (TME). To address these challenges, FeMOF/Pt/GOx (FMPG), a TME-responsive cascade nanoreactor, was designed for photothermal-cascade catalytic antitumor therapy. FMPG comprises MIL-100-(Fe), an iron-based metal–organic framework material, loaded with ultrasmall platinum nanoparticles (Pt NPs) and glucose oxidase (GOx). Within the TME, FMPG degrades in the presence of high phosphate concentrations, releasing GOx, Fe2+, and Pt NPs. GOx consumes glucose, reducing ATP levels in cells and inducing a starvation state in tumor cells. Subsequently, the H2O2 produced by GOx and overexpressed in tumor cells reacts with Fe2+ to generate hydroxyl radicals, facilitating cascade catalytic therapy. The Pt NPs exhibit catalase-like activity and catalyze the production of oxygen from H2O2, further enhancing starvation. Under 808 nm laser irradiation, the as-prepared composites generate localized heat, enabling effective photothermal therapy. This nanoreactor demonstrates efficient tumor inhibition by in situ consumption and production of compounds, promoting the development of precise synergetic cancer therapies with spatiotemporal controllability. [ABSTRACT FROM AUTHOR]

The safe use of methanol-reforming hydrogen fuel cells requires the accurate identification and detection of the gases involved in methanol and hydrogen. To address this issue, we construct unique gas sensors by uniformly growing zeolitic imidazolate framework (ZIF) (ZIF-67 and ZIF-8) particles on the surface of functionalized V2CTx (F-V2CTx), which are prealkalized and then grafted with (3-aminopropyl) triethoxysilane (APTES). In the achieved composite of F-V2CTx/ZIFs, V2CTx provides a fast electron transport channel, and ZIFs provide adsorption sites for specific gases. Thus, with different ZIF modifications, the V2CTx/ZIF-based sensors are modulated to realize the selective detection of methanol or hydrogen. This reveals that the F-V2CTx/ZIF-8 and F-V2CTx/ZIF-67 sensors exhibit fast response/recovery to hydrogen (5/4 s to 500 ppm H2) and methanol (3/12 s to 10 ppm methanol), respectively. The F-V2CTx/ZIF-67 sensor exhibits the capability of detecting sub ppm methanol, with a theoretical detection limit of 72 ppb, while the F-V2CTx/ZIF-8 sensor shows good selectivity to hydrogen at room temperature. The mechanisms for the gas-sensing enhancement and gas-selectivity modulation of V2CTx/ZIF sensors are clarified based on the heterojunction effect and first-principles calculations, respectively. This work expands the application of nanocomposites composed of V2CTx and ZIFs in the field of gas sensors and proposes an effective strategy for gas selectivity modulation by different ZIF modifications. [ABSTRACT FROM AUTHOR]

Carbon-doped MXene quantum dots (MNQDs) were synthesized through a hydrothermal reaction involving citric acid and ethylene diamine in the presence of MXene. Palladium nanoparticles were subsequently incorporated into the MNQDs and integrated into an iron-based metal–organic framework, forming MIL-PdMNQDs. The successful synthesis of MIL-PdMNQDs was confirmed by PXRD, SEM, TEM, XPS, and FTIR analyses. Modified glassy carbon and screen-printed electrodes with MIL-PdMNQDs were used to measure l-ascorbic acid concentrations in a phosphate buffer solution, ranging from 10 to 100 nM. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) revealed a linear anodic peak current between 52.05 and 82.44 μA, with a linear regression (R2) value of 0.9885. In human serum diluted with PBS (5 mL of serum in 95 mL of PBS), the MIL-PdMNQDs-SPE1 detected ascorbic acid concentrations from 10 to 50 μM, illustrating a DPV redox peak current between 124.39 and 152.54 μA, with an R2 of 0.9901. Additionally, in artificial sweat, the DPV sensor detected ascorbic acid concentrations ranging from 100 to 1000 μM, with current readings between 11.132 and 64.83 μA and an R2 value of 0.9903, demonstrating its selective sensing capability. The limit of detection (LOD) for ascorbic acid in PBS using MIL-PdMNQDs-GCE was determined to be 4.705 nM. The MIL-PdMNQDs-GCE and SPE sensors exhibited high stability and exceptional selectivity for ascorbic acid detection. [ABSTRACT FROM AUTHOR]

Understanding the structure of thin films is essential for successful applications of metal–organic frameworks (MOFs), such as low k-dielectrics in electronic devices. This study focuses on the thin film formation of the 3D nanoporous MOF Cu2(bdc)2(dabco). The thin films are prepared by a layer-by-layer technique with varying deposition cycles (1 to 50). Thin film morphologies and crystallographic properties were investigated using atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, and grazing-incidence X-ray diffraction (GIXD). AFM revealed an island growth (Volmer–Weber) with plate-like shaped islands. FTIR and GIXD revealed that Cu2(bdc)2(dabco) crystals form already during the first preparation cycle. The heights of the islands do not increase linearly with the number of deposition cycles, suggesting multiple growth stages. X-ray diffraction pole figures uncover a uniplanar texture of the Cu2(bdc)2(dabco) crystals, together with randomly oriented crystallites. The fraction of uniplanar oriented crystals increases with each deposition cycle, reaching a maximum of 75% at ten deposition cycles, simultaneously achieving complete substrate coverage. However, already at five cycles, an additional phase of randomly oriented copper-terephthalate (Cu2(bdc)) crystals appeared; this phase reaches a fraction of 22% at the largest film thickness (50 cycles). In summary, a detailed understanding of the thin film formation of an archetypal layer-pillar MOF is presented, elucidating how films grow in terms of their morphology and crystalline properties. Samples prepared by ten cycles show complete coverage of the substrate together with the highest degree of preferred crystal orientation. These results establish a deepened understanding of critical parameters for MOF thin film applications, such as complete substrate coverage and definition of the nanopores relative to the substrate surface. [ABSTRACT FROM AUTHOR]

With the accelerated progression of modern society, artificial colorants are utilized extensively for their attractive coloration. Herbicides are applied widely to control unwanted plants in agricultural fields which cause toxic effects on human health and the environment. The increased utilization of these toxic chemicals has necessitated the development of a highly sensitive sensor that can selectively identify these toxic chemicals. In this study, we explored a nanoscale Zr-(IV)-based metal–organic framework (MOF) (1′) as a fluorescence sensor toward precise recognition of food colorant tartrazine and herbicide metamitron. The quenching efficiency of 1′ toward tartrazine and metamitron was 93 and 88%, respectively. The limit of detection was found to be 5.7 nM for tartrazine and 13.7 nM for metamitron, which are remarkably lower than the other reported sensors. Moreover, the quick response time (<10 s for tartrazine and <20 s for metamitron) and recyclable property of 1′ made it a promising candidate for real-world application. Furthermore, 1′ was utilized for the detection of tartrazine in various food matrices, which displayed a very good recovery percentage. This study also highlights the potential of 1′ toward real-time detection of metamitron in different environmental water systems and a variety of pH media. Additionally, we have prepared cost-effective, user-friendly Zr-(IV) MOF-embedded chitosan on paper composite for the hands-on detection of tartrazine. We have elaborately investigated the mechanisms of fluorometric sensing with several instrumental techniques. Adsorption capacity of 1′ toward tartrazine was also measured and it showed fast adsorption (<1 min). It also displayed over 90% selectivity for adsorption of tartrazine in the presence of commonly occurring cations and anions. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs), known for their versatile structures and high porosity, have become a key focus in materials science with broad applications across multiple research areas. This review offers a prospective outlook, emphasizing the use of MOF-based ion-selective nanofluidic membranes in critical areas such as ion separation, seawater desalination, and energy conversion. It highlights the latest technological breakthroughs, discusses the underlying mechanisms, and evaluates the performance of these membranes in practical applications. Furthermore, the review provides a comprehensive summary and insightful recommendations for future directions, emphasizing the potential of MOF-based membranes in ion separation and sustainable energy production. [ABSTRACT FROM AUTHOR]

The inherent volume expansion of sulfur, the low conductivity of sulfur species, and the shuttle effects of lithium polysulfides (LiPSs) have limited the commercial deployment of lithium–sulfur (Li–S) batteries. Herein, a tungsten oxynitride skeleton featured with a three-dimensional ordered macroporous (3DOM) structure and embedded with ZIF-67-derived Co-NC nanoparticles (S/Co-NC/WNO) is developed as an effective sulfur host in Li–S batteries. The stable and unique 3DOM structure is conducive to electrolyte permeation and reduces the influence of the volume expansion. Nitrogen doping not only enhances the electrical conductivity of WO3 but also favors LiPS trapping. Meanwhile, Co-NC nanoparticles act as catalytic centers, promoting LiPS adsorption and catalytic conversion, leading to quick and durable Li–S chemistry. Therefore, S/Co-NC/WNO exhibits outstanding electrochemical performance. The initial discharge capacity is 1028.5 mAh g–1 at 0.2 C, and after 100 cycles, a discharge capacity of 938.0 mAh g–1 is maintained. Even under a sulfur loading of 8 mg cm–2, the Li–S battery was capable of reaching an areal capacity of 5.54 mAh cm–2. In addition, the flexible pouch cell based on S/Co-NC/WNO cathode also achieved stable cycling performance, which demonstrates its promising potential in Li–S battery applications. [ABSTRACT FROM AUTHOR]

Sonodynamic therapy (SDT) has demonstrated considerable potential in its noninvasive approach and ability to target tumors located deep within brain tissues (>10 cm). However, the effectiveness of this technique is hindered by tumor hypoxia (2% O2), the abundance of the reactive oxygen species (ROS) scavenger glutathione (GSH), and the limited ROS generation capacity of the sonosensitizer. In light of these limitations, a cascade nanozyme comprising platinum (Pt)-coated porphyrin metal–organic frameworks (PCN-224-(Fe)) modified with COOH-PEG was developed [Pt/PCN-224-(Fe)/PEG, labeled as PFMP nanozyme] to enhance the toxicity of ROS. This nanozyme emulates the catalytic function of Pt in the decomposition of hydrogen peroxide (H2O2) into O2 for the purpose of alleviating tumor hypoxia. Additionally, it replicates the function of glutathione peroxidase (GPX) by utilizing iron (Fe3+) to reduce the overexpression of GSH. These two mechanisms act in concert to amplify the generation of ROS. They achieve this by enhancing O2 production and impairing the capacity of GSH to scavenge ROS, thereby synergistically potentiating the toxicity of ROS. In vitro and in vivo studies have demonstrated evidence for efficient ROS generation, resulting in a significant 6-fold reduction in tumor volume compared to the control groups and achieving an impressive 80% survival rate 30 days after treatment. [ABSTRACT FROM AUTHOR]

Ischemic osteonecrosis, particularly glucocorticoid-induced osteonecrosis of the femoral head (GIONFH), is primarily due to the dysfunction of osteogenesis and angiogenesis. miRNA, as a therapeutic system with immense potential, plays a vital role in the treatment of various diseases. However, due to the unique microenvironmental structure of bone tissue, especially in the case of GIONFH, where there is a deficiency in the vascular system, it is challenging to effectively target and deliver to the ischemic osteonecrosis area. A drug delivery system assisted by genetically engineered cell membranes holds promise in addressing the challenge of targeted miRNA delivery. Herein, we leverage the potential of miR-21 in modulating osteogenesis and angiogenesis to design an innovative biomimetic nanoplatform system. First, we employed metal-organic frameworks (MOFs) as the core structure to load miR-21-m (miR-21-m@MOF). The nanoparticles were further coated with the membrane of bone marrow mesenchymal stem cells overexpressing CXCR4 (CM-miR-21-m@MOF), enhancing their ability to target ischemic bone areas via the CXCR4-SDF1 axis. These biomimetic nanocomposites possess both bone-targeting and ischemia-guiding capabilities, actively targeting GIONFH lesions to release miR-21-m into target cells, thereby silencing PTEN gene and activating the PI3K-AKT signaling pathway to regulate osteogenesis and angiogenesis. This innovative miRNA delivery system provides a promising therapeutic avenue for GIONFH and potentially other related ischemic bone diseases. 1. CXCR4-Engineered Membranes Enhance Targeting for Ischemic Osteonecrosis. 2. miR-21-Based Gene Therapy for Regulating Osteogenesis and Angiogenesis. 3. Expanding the Use of Membrane-Cloaked MOF Nanoparticles. [Display omitted] [ABSTRACT FROM AUTHOR]

Phosphate plays a crucial role in biological metabolism across both plants and animals, with abnormal concentrations often indicating various diseases. Despite the prevalence of the molybdenum blue detection method, certain issues persist, including difficulties in preservation and the need for fresh preparation. Here, we introduce a hydroxy-modified metal–organic framework, University of Oslo 66 (UiO-66-2OH), as a versatile platform for fluorescence probes capable of detecting phosphate concentrations in both botanical and clinical contexts. By changing modulator amounts and metal centers, we synthesized particles of varying sizes and active centers (Zr and Hf). Our investigations revealed that a 300 nm UiO-66-2OH particle with a Zr center was optimal for phosphate detection, achieving a limit of detection of 7 μM with low cost. Furthermore, we explored the potential agricultural and diagnostic applications. These findings underscored the versatility and promise of UiO-66-2OH as a sensing material for diverse biological and medical applications. [ABSTRACT FROM AUTHOR]

The hunt for stable and effective luminous materials has always been a major focus of investigation and research during the development of electrochemiluminescence (ECL). However, numerous challenges persist even in current times. The aggregation-induced emission (AIE) ligand 1,1,2,2-tetra-(4-carboxylbiphenyl)-ethylene and La3+ were used in this study to create a rod-like metal–organic framework (La-TCBPE-MOF, LTM), which was then constructed into an inventive ECL immunosensor for the ultrasensitive detection of neuron-specific enolase (NSE). LTM showed stronger ECL signals compared to H4TCBPE aggregations, which can be attributed not only to the immobilization of H4TCBPE ligands within the rigid MOF matrix, which restricted free intramolecular rotation and vibration, but also to the reduction of nonradiative transitions. Furthermore, the loading capacity of the H4TCBPE luminophore was significantly boosted by anchoring H4TCBPE into the rigid MOF as a bridging ligand. Consequently, a larger ECL intensity was produced due to the increased amount of H4TCBPE luminophores being stimulated. As anticipated, the fabricated ECL immunosensor exhibited a broad linear range spanning from 100 fg mL–1 to 100 ng mL–1, accompanied by an impressively low limit of detection (LOD) of 21.5 fg mL–1. Moreover, the ECL immunosensor was effectively utilized for measurement in human serum. In summary, this research demonstrated a successful integration of AIE into the field of ECL, enabling rapid, sensitive, and highly precise detection of NSE. [ABSTRACT FROM AUTHOR]

Copper is a toxic water contaminant; its quantification below the maximum contaminant level (MCL) of 1.3 ppm by a sensitive, field-deployable sensor becomes critical. Here, the cobalt-doped zeolitic-imidazolate framework (Co/ZIF-8) nanomaterial was developed as a novel, highly selective, sensitive, and stable chemoreceptor as an alternative to ZIF-8 for Cu-(II) ion detection. A dip-type optical absorption Cu-(II) ion sensor was realized by an in situ deposition of Co/ZIF-8 nanoparticles over a highly sensitive U-bent fiber optic sensor (FOS) probe with a remarkable high evanescent wave-based absorption (EWA) sensitivity. The Co/ZIF-8 coated FOS works on the principle of attenuation of the light passing through the FOS by the Co/ZIF-8 nanoparticles due to EWA at 400 nm wavelength upon interaction with Cu-(II) ions and increases proportional to the Cu-(II) ions concentrations. The interaction of Cu-(II) ions with Co/ZIF-8 nanoparticles was extensively characterized with the help of UV–visible absorption, scanning electron microscopy and EDAX analysis, X-ray diffraction, and FTIR absorption spectral analysis. Cu-(II) ions were found to replace Zn-(II) in the Co/ZIF-8, forming Cu-imidazole complexes over and off the nanoparticles, leaving the surface rich with Co- and Cu-imidazole complexes and thereby altering the optical and morphological properties of the Co/ZIF-8. The sensor demonstrated an excellent dynamic range of 0.05–100 ppm with an experimental LoD of 50 ppb using a simple LED-photodetector-based setup, selectivity for Cu-(II) against 12 other potential interfering metal ions, and a shelf life of at least 3 months. The facile and scalable Co/ZIF-8 deposition process, simpler instrumentation, excellent sensor parameters, and good recovery rates with field water samples make this strategy highly promising for on-site environmental monitoring. [ABSTRACT FROM AUTHOR]

As an emerging material with the potential to combine the high efficiency of homogeneous catalysts and high stability and recyclability of heterogeneous catalysts, metal‐organic frameworks (MOFs) have been viewed as one of the candidates to produce catalysts of the next generation. Herein, we heterogenized the highly active mono(phosphine)‐Pd complex on surface of UiO‐66 MOF, as a catalyst for Suzuki and Heck cross coupling reactions. The successful immobilization of these Pd‐monophosphine complexes on MOF surface to form UiO‐66‐PPh2–Pd was characterized and confirmed via comprehensive set of analytical methods. UiO‐66‐PPh2–Pd showed high activity and selectivity for both Suzuki and Heck Cross Coupling Reactions. This strategy enabled facile access to mono(phosphine) complexes which are challenging to design and require multistep synthesis in homogeneous systems, paving the way for future MOF catalysts applications by similar systems. [ABSTRACT FROM AUTHOR]

Water electrolysis is considered a compelling path for generating ecofriendly and sustainable hydrogen fuel. To realize highly effective electrocatalytic water splitting, improving anodic oxygen evolution reaction (OER) activity is key because of its high overpotential. The urea oxidation reaction (UOR) is a promising method instead of the OER. Herein, a series of bimetallic nanoporous M2V-MOF materials (M = Fe, Co, and Ni) with vanadium doping is successfully synthesized by a one-step hydrothermal method and the materials are applied as electrocatalysts for water and urea electrolysis. Among the as-synthesized M2V-MOF materials, Fe2V-MOF as an impressive trifunctional electrocatalyst has very low overpotentials of 291 mV@10 mA cm–2 for the OER, 1.48 V@50 mA cm–2 for the UOR, and 182 mV@–10 mA cm–2 for the hydrogen evolution reaction (HER). Adapting it as a cathode and anode electrode for water splitting in 1.0 M KOH, a low cell voltage of 1.73 V is required for delivering 10 mA cm–2. The urea-assisted electrolysis cell only needs 1.63 V to drive a current density of 10 mA cm–2 and exhibits excellent stability over 60 h. [ABSTRACT FROM AUTHOR]

Rapid interest in identifying specific biomarkers has been sparked by the development of wearable electrochemical sensors for physiological and biological monitoring via noninvasive measurement. During anaerobic metabolic circumstances, monitoring the lactate content become critical for noninvasive diagnostic of hypoxia. To improve the sensitivity of wearable sweat biosensors for detecting lactate concentrations, in this study, metal–organic framework (MOF)-derived NiCo-based layered double hydroxides (m-NiCo LDHs) with N-doped graphene quantum dots (NGQDs) decoration are designed. According to the X-ray absorption spectroscopy (XAS) analysis, the incorporation of NGQDs will alter the local electronic structure of transition metals in m-NiCo LDHs, thereby reducing the charge transfer resistance and accelerating the electron transfer kinetics during electrochemical reactions of lactate detection. After understanding the role of NGQDs in the matrix of m-NiCo LDHs, as-designed NGQD/m-NiCo LDH-based electrochemical biosensors for lactate detection displayed superior sensitivity of 62.63 ± 1.50 μA mM–1 cm–2 under an applied potential of 0.60 V (vs Ag/AgCl/3 M KCl) with the lactate concentration range of 0 to 15 mM in alkaline condition, compared to pristine NiCo LDH (16.77 ± 1.70 μA mM–1 cm–2)- and m-NiCo LDH (45.45 ± 4.39 μA mM–1 cm–2)-based ones. This research provides a potential electrocatalyst of GQD-modified MOF-derived LDHs for using enzyme-free electrochemical lactate sensors with reliable and stable performance in order to implement noninvasive human perspiration monitoring on wearable bioelectronics. [ABSTRACT FROM AUTHOR]

Metal–organic framework (MOF)-derived magnetic metal/carbon nanocomposites have evolved as prospective functional materials with application in the electromagnetic wave (EMW) absorption field due to their tailorable dielectric–magnetic characteristic. Nonetheless, a significant challenge remains in regulating the microstructure of MOF-derived nanomaterials to acquire excellent EMW absorption. Herein, NiCo alloy and N-doped bamboo-like carbon nanotube network (NiCo@CNTs/NC) magnetic–dielectric composites were fabricated using a one-dimensional (1D) NiCo-MOF nanobelt as precursor through a one-step melamine-assisted pyrolyzing process. The interconnected carbon nanotube network structure offers multiple electronic migration and hop paths and effectively facilitates conductive loss. The adjustable Ni/Co nodes in the 1D MOFs were effectively transformed into NiCo alloy nanoparticles and confined within the tips of the in situ-generated interconnected CNT networks. Such well-dispersed and nanoconfined magnetic NiCo nanoparticles generate a nanoscale magnetic coupling network and provide a high density of polarized sites, reinforcing the magnetic–dielectric coupling ability as well as triggering interfacial polarization. Consequently, the optimized NiCo@CNTs/NC-20/1 composite achieves glorious EMW absorption with a strong reflection loss (RLmax) of −30.31 dB at only 1.4 mm thickness and an effective absorption bandwidth as wide as 4.5 GHz at 1.6 mm thickness when the filling fraction is 20 wt %. Considering the excellent EMW absorption properties, we believe that this work will provide new insights into the design of magnetic metal/carbon nanocomposites that enhance EMW absorption properties through the reasonable construction of low-dimensional interconnected magnetic–dielectric networks with magnetic nanoparticles in nanoconfined spaces. [ABSTRACT FROM AUTHOR]

Nanocoral arrays of Co-(OH)-F@NiCo-LDH/Co9S8 have been successfully synthesized onto nickel foam via a solvothermal method. The prepared heterostructured nanocage demonstrates outstanding electrochemical properties such as excellent specific capacitance (3409 mC cm–2 at 1 mA cm–2) and superior capacity retention (96.38% retention after 7000 charge–discharge cycles at 10 mA cm–2). The asymmetrical supercapacitor fabricated by reduced graphene oxide and Co-(OH)-F@NiCo-LDH/Co9S8 showed an excellent energy density of 37.2 W h kg–1 at a power density of 800 W kg–1 and superior capacity storage (87.63% retention after 5000 cycles of charge–discharge). This suggests that the composite has excellent performance for electrochemical supercapacitor applications. The unique combination of materials and structural design strategy employed highlight the significant advancements to develop high-performance supercapacitors, positioning this study at the cutting edge of nanomaterials research in energy applications. [ABSTRACT FROM AUTHOR]

The nanointerfaces of ZnO-Cu and the size of active nanoparticles (NPs) play crucial roles in the development process of CO2 hydrogenation. Herein, Zn-PBC80 with an unsaturated coordination Zn2+ center was constructed from Zn-(NO3)2·6H2O and 3,5-bis-(4′-carboxyl-phenyl) pyridine (H2PBC), serving as an anchoring site for supporting Cu2+ and a platform for encapsulating NPs. The different loading concentrations of Cu2+ and pyrolysis of the MOFs-based precursor vary the chemical environments of the catalysts, resulting in different distributed states and average sizes of active sites. Specifically, the pyrolysis of Zn-PBC80-Cu-1 with a concentration ratio of 1:1 facilitates the construction of an interfacial ZnO-Cu nanocomposite and smaller NP size. Among a series of CO2 catalysts, the resultant ZnO-Cu-1-700 exhibits the best catalytic performance with a satisfying CO2 conversion rate (16.5%), outstanding CO selectivity (100%), and promoting catalytic stability over 30 h. The best catalytic performance could be attributed to the more stable electronic structure of metallic Cu NPs and the generation of oxygen vacancies resulting from the unique ZnO-Cu nanointerfaces among the catalysts. This discrepancy in catalytic performance indicates that the active nanointerfaces affects the electronic structure of active centers, providing valuable insight into the design of efficient catalysts for CO2 reduction. [ABSTRACT FROM AUTHOR]

Addressing the critical scientific challenge of enhancing the catalytic efficiency of transition metal-based metal–organic framework (MOF) materials in the two-electron oxygen reduction reaction (2e– ORR) for the electrochemical synthesis of H2O2 is of paramount importance in a related field. In this context, we had developed an interface synthetic strategy for constructing a series of bimetallic Ni–M (M = Co, Fe, Cu) center MOFs. This approach capitalized on the strong synergy among metallic ions, effectively regulating the electronic structure and thereby improving the catalytic activity of Ni active sites. Notably, the proposed Ni–Co MOF catalyst demonstrated exceptional 2e– ORR activity, achieving a remarkable H2O2 selectivity of up to 96%. This performance significantly surpassed that of Ni–Fe (54%) and Ni–Cu (67%) MOFs, as well as many other reported transition metal catalysts. Detailed studies on the structure–function relationship at the atomic level unveiled that Ni species in a high oxidation state, effectively regulated and stabilized by adjacent Co2+ ions, played a pivotal role in ensuring the superior 2e– ORR activity of the Ni–Co MOF. These physical-chemical insights into the reaction mechanism and structure–function relationships offer valuable guidance for the rational design of highly efficient MOF-based catalysts and reaction systems for on-site electrochemical synthesis of H2O2 via a 2e– ORR process. [ABSTRACT FROM AUTHOR]

Efficient chemodynamic therapy requires the intracellular self-supply of H2O2 with the simultaneous depletion of glutathione (GSH). The anticancer drug doxorubicin (DOX) was loaded onto CaO2 nanoparticles followed by encapsulation of CaO2-DOX into a Cu-based metal–organic framework (CuMOF), which was surface modified with poly-(ethylene)-glycol (PEG) to form the CaO2-DOX-CuMOF/PEG nanoplatform. This preparation functioned as a GSH-responsive, self-sufficient chemo–chemodynamic anticancer agent, which simultaneously generated oxidative stress endogenously and released DOX. GSH-rich cancer cells disintegrated CaO2-DOX-CuMOF/PEG to release DOX and CaO2, promoting the formation of H2O2 and thus favoring the generation of reactive oxygen species (ROS). Its antiproliferative properties were evaluated in vitro in lung adenocarcinoma cells by conducting studies on cytotoxicity, intracellular ROS generation, and mitochondrial membrane potential. In the in vivo mice tumor model, the combined chemo–chemodynamic therapy with the synthesized nanocomposite was superior in suppressing tumors than the individual therapies. Thus, this class of MOF nanoplatforms, which has the potential to be assigned with various drugs, can prove to be a valuable tool in cancer therapy. [ABSTRACT FROM AUTHOR]

The design and synthesis of metal–organic frameworks (MOFs) for direct use as electrode materials are crucial for enhancing the electrocatalytic oxygen evolution reaction (OER). Herein, the ultrathin MIL-53-(Fe) nanosheet arrays with enriched coordinatively unsaturated metal sites (denoted as MIL-53-(Fe)/NF-B0.2-2) are obtained under the inhibition and modulation of benzoic acid (BA) ligands via a substitution-suppression process. The results confirm that this unique ultrathin structure effectively increases the electrochemical active surface areas (ECSA) and exposes the coordinatively unsaturated metal sites. More importantly, the enriched coordinatively unsaturated metal sites acting as active sites facilitate the adsorption of OH– during the OER process. Additionally, MIL-53-(Fe)/NF-B0.2-2, with its optimized energy band structure, exhibits superior charge transfer ability and diffusion processes, significantly improving the reaction kinetics in alkaline electrolytes. As a result, the MIL-53-(Fe)/NF-B0.2-2 electrode only requires extremely low overpotentials of 190 and 229 mV to reach current densities of 10 and 100 mA cm–2 for OER, respectively. This research not only proposes a novel strategy for designing efficient electrocatalysts but also provides insights into the structure–activity relationship, advancing the rational design of MOFs as effective electrode materials. [ABSTRACT FROM AUTHOR]

Quantitative analysis of harmful patina components on the surface of bronzeware is crucial as patina can corrode artifacts. Surface-enhanced Raman spectroscopy (SERS) has a common application in surface analysis. However, there exists an absence of documented investigations concerning the quantitative analysis of detrimental patina, particularly the chloride patina. To achieve high sensitivity in targeting harmful patina, we report a fabrication method for constructing Ag/Au alloys in the pores and on the surface of UiO-66 (zirconium 1,4-dicarboxybenzene metal–organic framework) nanomaterials, resulting in Ag/Au/UiO-66 nanoparticle monolayers formed by self-assembly at the oil–water interface. By incorporating them onto the surface of PVA hydrogel, we obtained SERS sensor devices with excellent flexibility, outstanding optical transparency, and ultrahigh activity. These sensor devices efficiently sample irregular surfaces and detect micrometer-scale specimen. They significantly enhance the Raman characteristic peaks of measured objects, facilitating precise analysis of the patina composition on the surface of bronze artifacts. The Raman peak at 118 cm–1 was boosted from 367 to 11,909 for detecting harmful patina, and the enhancement factor of the SERS substrate was calculated to be 3.6 ×1010 for detecting the Raman peak of rhodamine 6G (R6G), which could be easily detected at 610 cm–1 at a concentration of 10–13 mol/L (M). The Raman peaks at 610 cm–1 from the SERS substrate could also be readily detected. By grafting the organic fluorescent group amino-MQAE onto the surface of Ag/Au/UiO-66 nanoparticles (NPs), the content of harmful patina on the surface of bronze artifacts treated for different durations was indirectly determined. These results indicate the successful construction of the Ag/Au alloy on the surface of UiO-66 NPs, resulting in SERS sensor devices with excellent flexibility, optical transparency, and ultrahigh sensitivity. [ABSTRACT FROM AUTHOR]

At present, supercapacitors (SC) based on metal–organic frameworks (MOFs) have gained a lot of attention in energy storage and conversion applications because of their fascinating properties such as low densities, variable chemical functions, high surface area, and porosity. The manuscript covers the synthesis of bimetallic MOF and MOF-derived ferrites via a chemically wet route and heat treatment process, respectively. The prepared electrode material was utilized to construct the asymmetric supercapacitor devices. The MnFe2-MOF electrode exhibits outstanding electrochemical properties over the derived MnFe2O4 along with high reversibility, fast kinetics, low charge transfer resistance (2.9 Ω), and an excellent specific capacitance of 1226 F g–1 at a current density of 1 mA cm–2 with a superb cyclic stability of approximately 90.74% of the initial capacitance even after 5000 subsequent charge–discharge cycles. Additionally, an asymmetric device was fabricated to confirm the practical viability of MnFe2-MOF as an anode and activated carbon as a cathode. The fabricated asymmetric device demonstrates an excellent specific capacitance of 91.87 F g–1 at a 1 mA cm–2 current density with a specific energy of 32.67 Wh kg–1 and a high specific power of 1000 W kg–1. Simultaneously, the fabricated asymmetric supercapacitor (ASC) device unveils exceptional cyclic stability (85.25%) and Coulombic efficiency (96.81%) at a higher current density of 8 mA cm–2 even after 10,000 charge–discharge cycles. These perceptible results based on MOF-derived ferrite nanostructure can make it a significant electrode material for supercapacitor application in today's technological applications. [ABSTRACT FROM AUTHOR]

SBA-15@MOF-525 composites were constructed by in situ self-assembly of a metal–organic framework (MOF-525) with mesoporous SBA-15 silica. MOF-525 crystals were confined inside the mesopores as well as grown on the outside surface of SBA-15, under the impact of the structure-directing role of SBA-15, and the composites exhibited both microporous and mesoporous characteristics. In general, the adsorption of tetracycline (TC) on MOF-525 was affected by pH. The adsorption capacity of MOF-525 decreased rapidly, especially in an alkaline environment, due to the collapse of the MOF-525 skeleton. By contrast, incorporating MOF-525 into SBA-15 improved the stability of MOF-525. The adsorption of TC on SBA-15@MOF-525 was almost unaffected by pH. High and stable adsorption capacity over a wide pH range was maintained under acidic, neutral, and alkaline environments. The composites were used effectively for TC adsorption. The maximum adsorption capacity of TC on SBA-15@MOF-525 was 690 mg/g, which is higher than that of most of the reported adsorbents. The great potential of SBA-15@MOF-525 in practical applications was demonstrated by investigating the adsorption of TC in lake water samples. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman scattering spectroscopy (SERS) can provide molecular fingerprint peaks of the vibration information with great specificity and sensitivity. It is widely used in biomedical and chemical fields. Semiconductor-based substrates represent a hot spot in the field of SERS beyond conventional noble metals, and metal–organic frameworks are rarely realized for SER detection. Here, we modulate the energy-band structures of metal–organic frameworks (MOFs) further by metal oxides (MOs) to match the energy band of a target analyte. We construct MOF-encapsulated metal oxide core–shell nanoparticles (MO@MOFs) as substrates for Raman enhancement. Attributed to the high structural tailorability of both core and shell, a series of energy-band structures have been created. We perform SERS detection of rhodamine b (RhB) on MO@MOF and find that the enhanced factor of Fe3O4@MOF-(Co) and TiO2@MOF-(Ni) reach as high as 108 and 106, respectively, with low detection limits of 10–8 M, much lower than that using the corresponding MOFs. The SERS enhancement is based on mechanisms including charge transfer, interband and molecule resonances, and ground-state charge-transfer interactions. This work will promote the application of semiconductor-based nanomaterials with special modularity for surface-enhanced Raman scattering substrates. [ABSTRACT FROM AUTHOR]

The rational design of nanomaterials derived from a metal–organic framework (MOF) has received a lot of interest due to their high potential for energy-storage and conversion applications, which are because of their high conductivity, strong redox activity, and large specific surface area. In this study, a "one-for-all" approach was used to synthesize positive and negative electrodes from a single bimetallic cobalt–iron metal–organic framework (CoFe2-MOF) to fabricate a hybrid supercapacitor (HSC) device. Hierarchical bimetallic CoFe2-MOF architectures were synthesized by a straightforward and scalable solution method. The cobalt ferrite was prepared by annealing the bimetallic CoFe2-MOF in air, and the nanoporous carbon (NPC) was achieved by heating the CoFe2-MOF in an inert atmosphere. The CoFe2-MOF-derived NPC exhibits a high specific capacitance of 1271 F g–1 at 2 mA cm–2 current density with an excellent cycle stability of 96.87% even after 5000 cycles due to its huge surface area of 614 m2 g–1 and plenty of mesopores in it. The as-prepared cobalt ferrite and NPC derived from CoFe2-MOF were employed to construct the "all-in-one" HSC device using poly-(vinyl alcohol)–potassium hydroxide as a gel–polymer electrolyte. At 1 mA cm–2 current density, the manufactured "all-in-one" HSC device shows a high specific capacitance of 112.1 F g–1, an energy density of 56.2 Wh kg–1, and a power density of 1091.5 W kg–1. It demonstrated a high cyclic stability of 97.91% of its original capacitance over 5000 subsequent galvanostatic charge–discharge cycles with a Coulombic efficiency of 98.54%. This discovery might significantly progress research toward the creation of MOF-derived electrode materials for a bright future in energy-storage and conversion. [ABSTRACT FROM AUTHOR]

The adsorption capacity (AC) of the material can be significantly enhanced by the composite synergy between various metals, which in turn modifies the morphology, structure, and functional groups of the material. In this view, the nanoporous bimetal metal–organic frameworks (MOFs) using metals (Ce, Fe, Al, and La), namely, Ce@Fe1:1, Ce@Al1:1, and Ce@La1:1, were synthesized via a one-pot method. The nanoporous bimetal MOFs applied to remove F– ions from drinking water followed the order of Ce@Fe1:1 > Ce@Al1:1 > Ce@La1:1. Based on the above findings, Ce@Fe1:1 was further synthesized using cerium and iron at different molar ratios to optimize the best possible compositions, namely, Ce-Fu, Ce@Fe2:1, Ce@Fe1:1, Ce@Fe1:2, and Fe-Fu. These nanoporous bimetal MOF composites were applied to remediate the F– ion from wastewater and Ce@Fe1:1 exhibited the maximum AC of 84.4 mg g–1 at 288 K. It is worth mentioning that the utilization of ultrasonication as a mediator for the adsorption study over the conventional method gives excellent relaxation in time as it enhances the reaction kinetics. As a result, the study demonstrated rapid adsorption kinetics, which follows the pseudo-second-order (PSO) model. Moreover, coexisting ions such as NO3–, Cl–, HCO3–, and SO42– had less effect on the adsorption of fluoride. The adsorption mechanism of Ce@Fe1:1 bimetal MOFs supports the electrostatic attraction and ligand exchange processes, which were confirmed using characterization instruments, such as X-ray photoelectron spectroscopy (XPS) and zeta potential. [ABSTRACT FROM AUTHOR]

Herein, a nanoporous metal–organic framework (UiO-66-H1/H2) was constructed, which was developed as a universal platform for rare earth (RE) ion adsorption. In detail, 1,2,4,5-benzenetetracarboxylic acid (H2 linker) and 1,2,4-benzenetricarboxylic acid (H1 linker) were simultaneously introduced to construct the mixed-linker UiO-66-H1/H2. Compared with UiO-66-H2, the slightly reduced carboxyl groups of UiO-66-H1/H2 boost the specific surface area. This feature as well as the nanoscale particle promotes the diffusion and mass transfer efficiency of guest ions in the adsorbent channel. Meanwhile, the triangular-window channel shows an angstrom-level carboxyl-rich trap, whose size suits well with the diameters of the RE ions. Benefiting from these advantages, effective adsorption for various RE ions was achieved in the optimized UiO-66-H1/H2-a, with large capacities of 150–250 mg g–1 and rapid kinetics (∼30 min for equilibrium). Ionization of carboxyl induces the negatively charged surface of UiO-66-H1/H2-a, which facilitates the diffusion of cationic RE ions via electrostatic interactions. Meanwhile, the strong chelation interaction from free carboxyl groups contributes largely to the tight capture of RE ions, as proved by experiments and theoretical calculations. These results suggest that UiO-66-H1/H2-a is an effective adsorbent for the capture and recovery of RE ions. We expect that this work can provide an interesting insight into the balance group number and porosity. [ABSTRACT FROM AUTHOR]

The presence of antibiotics in aquatic environments has recently raised significant concerns due to their toxic effects as well as the propagation of antibiotic resistances. Thus, efforts are devoted to developing facile screening methods for sulfonamide antibiotics in waters. In this study, we designed a fluorescent array comprising three structurally different pyrene-based luminescent metal–organic framework (LMOF) sensors and applied it in the simultaneous screening of multiple sulfonamides. The pyrene-based LMOFs produced fluorescence quenching responses to sulfonamides via the static quenching mechanism and/or inner filter effect. The array was able to effectively sense and discriminate five structurally similar sulfonamides (sulfamethoxazole, sulfadiazine, sulfapyridine, sulfamerazine, and sulfamethazine), individual sulfonamide at different concentrations, and mixtures of two sulfonamides with various molar ratios. The detection limit of the pyrene-based MOF array for individual sulfonamide was lower than most previously reported fluorescent sensors. It also afforded a fast sulfonamide response (response equilibrium <2 min) owing to the open and uniform nanoporous structures of the LMOF array elements, which allowed a screening speed as fast as approximately 20 min/100 samples. The constructed array exhibited good performance in the discrimination of sulfonamides in real water samples, validating its practicability. This study provides a convenient strategy for the rapid screening of sulfonamide antibiotics in aquatic environments. It also validates the application potential of LMOF array in fluorescence sensing fields. [ABSTRACT FROM AUTHOR]

In some important chemical processes, selective removal of C2H2 from other gases is necessary. The method of selecting porous materials for separation is energy-efficient and economical in comparison with some traditional methods, such as solvent extraction and low-temperature distillation. Herein, we present three nanoporous Cu-(II)-adenine-based metal–organic frameworks (MOFs), [Cu-(AD)-(AC)], [Cu2(AD)2(SA)], and [Cu2(AD)2(GA)], denoted as Cu-AD-AC, Cu-AD-SA, and Cu-AD-GA, respectively (HAD = adenine, HAC = acetic acid, H2SA = succinic acid, and H2GA = glutaric acid). The adenine ligands and secondary aliphatic acid ligands of these MOFs are easy-accessible. The MOFs show isomorphic three-dimensional (3D) microporous framework structures with slightly different pore microenvironments due to the presence of different aliphatic acid ligands. There are 1D channels of ∼4.5 to ∼5 Å diameter in the MOFs, the surfaces of which are decorated with a Lewis basic site. The subtle structural differences lead to large differences in the stability and porosity of the MOFs. Among them, Cu-AD-SA showed a relatively high adsorption capacity of C2H2. In addition, adsorption isotherm measurements for single-component gases and breakthrough experiments for binary gas mixtures suggested that Cu-AD-SA could selectively adsorb C2H2 from a C2H2/C2H4 or a C2H2/CO2 mixture. [ABSTRACT FROM AUTHOR]

Adsorptive separation by porous solids provides an energy-efficient alternative for the purification of important chemical species compared to energy-intensive distillations. Particularly, the separation of linear hexane isomers from its branched counterparts is crucial to produce premium grade gasoline with high research octane number (RON). Herein, we report the synthesis of a new, flexible zinc-based metal-organic framework, [Zn5(μ3-OH)2(adtb)2(H2O)5·5 DMA] (Zn-adtb), constructed from a butterfly shaped carboxylate linker with underlying (4,8)-connected scu topology capable of separating the C6 isomers nHEX, 3MP, and 23DMB. The sorbate-sorbent interactions and separation mechanisms were investigated and analyzed through in situ FTIR, solid state NMR measurements and computational modeling. These studies reveal that Zn-adtb discriminates the nHEX/3MP isomer pair through a kinetic separation mechanism and the nHEX/23DMB isomer pair through a molecular sieving mechanism. Column breakthrough measurements further demonstrate the efficient separation of linear nHEX from the mono- and dibranched isomers.

Owing to the mixed insertion and multielectron conversion reaction mechanisms, nonstoichiometric copper selenide (Cu2–xSe) has been known as a potential anode for lithium-ion batteries. However, huge volume changes during discharge and charge limit its ability for lithium-ion storage. Constructing heterophase nanocomposite uniformly distributed in the carbon network has been recognized as an effective approach to address the above issue. In this work, polyoxometalate-based metal–organic frameworks were used as the self-template to derive octahedral mesoporous carbon-coated heterophase copper selenide and molybdenum dioxide (MoO2/Cu2–xSe@C) nanocomposites, and the phase transformation of copper selenides from CuSe to Cu2–xSe can be achieved by tuning the pyrolysis temperature, thus optimizing the electrochemical performance. As a result, the optimized electrode delivers a high reversible specific capacity of 864.8 mAh g–1 at 0.2 A g–1 after 100 cycles, an excellent rate capability with a capacity of 480.9 mAh g–1 at 2.0 A g–1, and a long-term stability up to 500 cycles with a capacity decay rate per cycle of only 0.003%. Also, the reaction mechanism and structural stability after cycling were analyzed in detail. [ABSTRACT FROM AUTHOR]

Carbon mitigation is one challenging issue that the world is facing. To tackle the deleterious impacts of CO2, processes emerged, including chemisorption from amine-based solvents and, more recently, physisorption in nanoporous solids. Physisorption in metal–organic frameworks (MOFs) is currently attracting considerable attention; however, the selection of the optimum sorbent is still challenging. While CO2 adsorption by MOFs has been widely explored from a thermodynamics standpoint, dynamical aspects remain less explored. CALF-20-(Zn) MOF was recently proposed as a promising alternative to the commercially used CO2 13X zeolite sorbents; however, an in-depth understanding of the nanoscopic mechanisms originating its good performance still has to be achieved. To do so, we deliver some insights into the adsorption and diffusion of CO2, H2O, and mixtures in CALF-20 through atomistic simulations. CALF-20-(Zn) was revealed to exhibit unconventional guest–host behaviors that give rise to abnormal guest thermodynamics and dynamics. The hydrophobic nature of the nanoporous solid leads to a low water adsorption enthalpy at low loading, followed by a continuous increase, driven by strong water hydrogen bonds, found to arrange as quasi 1D molecular wires in MOF nanoporosity, recalling water behavior in small-diameter carbon nanotubes. While no superdiffusion was found in the CALF-20-(Zn) as compared to carbon nanotubes, this behavior was shown to impact the guest-loading diffusion coefficient profile, with the presence of a minimum that correlates with the inflection point in the adsorption isotherm corresponding to the H2O wires formation. Interestingly, the diffusion coefficients of CO2 and H2O were also found to be of the same order of magnitude, with similar nonlinear profiles as a function of the guest loading. We further demonstrated that the diffusion coefficient for CO2 in the presence of water decreases with increasing water loading. [ABSTRACT FROM AUTHOR]

Exosomes are emerging cancerous biomarkers, while reliable, convenient, and highly sensitive analysis remains challenging. Herein, we report a dual metal–organic framework (MOF)-based electrochemical biosensor for directly capturing and detecting cancerous exosomes in complex biological samples. This biosensor comprises three key components, that is, a pH-sensitive ZIF-8-engineered screen-printed carbon electrode for signal transduction, a pH-insensitive magnetic nanoparticle-modified copper-based MOF (MNP/Cu-BTC MOF) for exosome collection, and a DNA logic system for DNA computation. MNP/Cu-BTC MOF can directly and rapidly collect exosomes from biological media without the use of expensive antibodies or time-consuming centrifugation processes. By introduction of a DNA-based logic system, streptavidin-glucose oxidase (SA-GOx) can be chemically bonded to the surface of exosomes through the biotin–streptavidin interaction. This fabricated biosensor allows ultrasensitive detection of exosomes through the combination of magnetic enrichment, acidification of the solution around the electrode through enzymatic catalysis of glucose to gluconic acid, and ZIF-8-mediated signal transduction as an exosome capture tool. The fabricated biosensor allows label-free detection of exosomes ranging from 104 to 108 particles mL–1 with a limit of detection of 2.2 × 104 particles mL–1. With its capacity for simple exosome collection, accurate identification, and sensitive detection, the proposed biosensor may accelerate the translation of exosome analysis for routine clinical testing. [ABSTRACT FROM AUTHOR]

Highly efficient and reusable protective materials for chemical warfare agents (CWAs) are in high demand. Here, we used a surface modification technique to develop a material that provides chemical protection. Using an electrospun polyacrylonitrile (PAN) nanofiber membrane as the substrate, we modified the surface of the nanofiber with dopamine hydrochloride, which self-polymerized to form a polydopamine (PDA) surface layer, onto which we loaded metal–organic framework (MOF-808) particles. The presence of PDA on the surface of the PAN nanofibers significantly increased the breaking strength (2-fold increase) and elongation (9-fold increase) of the nanofiber membrane. Moreover, the PDA functionalities formed coordination sites to trigger the in situ growth of MOF-808 particles on the surface of the nanofiber membrane, thereby considerably increasing the growth rate and loading capacity. The surface of the nanofiber membrane was completely covered with MOF-808 particles following solvothermal treatment for 16 h. The MOF-808/PAN/PDA composite membrane could rapidly degrade 99.9% of dimethyl-4-nitrophenyl phosphate to p-nitrophenol within 8 min. After the membrane was used several times, the conversion rate stabilized at 95.9%, indicating that the MOF-808/PAN/PDA composite membrane has significant potential for application as protective clothing for CWAs. [ABSTRACT FROM AUTHOR]

Rational design of a hierarchical core–shell structured photocatalyst is crucial for enhancing the separation and transport efficiency of photogenerated carriers, thereby improving the photocatalytic degradation efficiency. In this study, hollow polyhedral CoSx was first synthesized by utilizing dodecahedral Co-based metal–organic framework (ZIF-67) as a Co source and template, followed by introducing In and S species to fabricate hierarchical core–shell In2S3/CoSx composites. The resulting In2S3/CoSx porous hollow heterostructured composites exhibited an accelerated interfacial carrier transfer ratio and enhanced photocatalytic removal performance of tetracycline hydrochloride (TCH). Among them, the optimized sample In2S3/CoSx-2 (CoIS-2) demonstrated the highest TCH removal rate of 0.0324 min–1, which was 22.8 times higher than that of pristine CoSx and 5.7 times higher than that of pure In2S3, respectively. Moreover, its apparent quantum efficiency reached 4.66% at 420 nm. Electron spin resonance analysis and active substance capture experiments confirmed that superoxide radical (•O2–) played a predominant role in the reaction system. Furthermore, we investigated the dynamics of photoinduced carriers through a series of photoelectric tests combined with density functional theory calculations. This study provides valuable insights into controllable construction of metal–organic framework-based materials with high photocatalytic degradation efficiency and stability. [ABSTRACT FROM AUTHOR]

To meet the requirements for commercial application, more and more attention has been paid to the oxygen evolution reaction (OER) catalytic performance under high-current conditions. In this article, carbon nanohorns (CNHs) filled with Ni nanoparticles can be obtained through a one-step method, and then the core-shell structured Ni@NiS 2 encapsulated by N-doped carbon nanohorns (Ni@NiS 2 @CNHs) were obtained through a vulcanization process. Ni@NiS 2 @CNHs only requires a small potential of 400 mV to drive a high current density of 100 mA cm−2. Unfortunately, due to the strong agglomeration effect of nanopowders, the stability of Ni@NiS 2 @CNHs is slightly lower than that of other excellent catalysts. In this case, Ni+ deposited on the Ni@NiS 2 @CNHs was used as metal source to grow Ni-MOF by solvothermal method, ultimately obtaining Ni@NiS 2 @CNHs@MOF. It is found that this unique structure improves the electrocatalytic performance and stability of the composites. Thanks to the synergistic effect of multiphase nanostructures, Ni@NiS 2 @CNHs@MOF exhibited improved electrocatalytic performance. The underlying reason is that core-shell structured Ni@NiS 2 @CNHs can be stability and uniformly embedded on the layered structure of MOF, thus the long-time stability can be enhanced. To drive current density of 50 mA cm−2, 100 mA cm−2 and 200 mA cm−2 for OER, Ni@NiS 2 @CNHs@MOF only require potentials of 260 mV, 290 mV, and 310 mV, respectively, which is superior to most reported non noble metal catalysts. Combined with its excellent long-term stability, Ni@NiS 2 @CNHs@MOF can meet the requirements of commercial catalysts. [ABSTRACT FROM AUTHOR]

Diamine-appended variants of the metal-organic framework M2(dobpdc) (M = Mg, Mn, Fe, Co, Zn; dobpdc4- = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate) exhibit exceptional CO2 capture properties owing to a unique cooperative adsorption mechanism, and thus hold promise for use in the development of energy- and cost-efficient CO2 separations. Understanding the nature of thermal transport in these materials is essential for such practical applications, however, as temperature rises resulting from exothermic CO2 uptake could potentially offset the energy savings offered by such cooperative adsorbents. Here, molecular dynamics (MD) simulations are employed in investigating thermal transport in bare and e-2-appended Zn2(dobpdc) (e-2 = N-ethylethylenediamine), both with and without CO2 as a guest. In the absence of CO2, the appended diamines function to enhance thermal conductivity in the ab-plane of e-2-Zn2(dobpdc) relative to the bare framework, as a result of noncovalent interactions between adjacent diamines that provide additional heat transfer pathways across the pore channel. Upon introduction of CO2, the thermal conductivity along the pore channel (the c-axis) increases due to the cooperative formation of metal-bound ammonium carbamates, which serve to create additional heat transfer pathways. In contrast, the thermal conductivity of the bare framework remains unchanged in the presence of zinc-bound CO2 but decreases in the presence of additional adsorbed CO2.

Therapeutic enzymes used for genetic disorders or metabolic diseases oftentimes suffer from suboptimal pharmacokinetics and stability. Nanodelivery systems have shown considerable promise for improving the performance of enzyme therapies. Here, we develop a cell membrane-camouflaged metal-organic framework (MOF) system with enhanced biocompatibility and functionality. The MOF core can efficiently encapsulate enzymes while maintaining their bioactivity. After the introduction of natural cell membrane coatings, the resulting nanoformulations can be safely administered in vivo. The surface receptors on the membrane can also provide additional functionalities that synergize with the encapsulated enzyme to target disease pathology from multiple dimensions. Employing uricase as a model enzyme, we demonstrate the utility of this approach in multiple animal disease models. The results support the use of cell membrane-coated MOFs for enzyme delivery, and this strategy could be leveraged to improve the usefulness of enzyme-based therapies for managing a wide range of important human health conditions.

CsPbBr3 perovskite nanocrystals (CNCs) have emerged as promising candidates for optoelectronics, although instability issues have retarded their progress toward commercialization. As a solution to this core issue, herein CNCs are bound to the metal–organic framework MOF-5 to form a stable composite MOF:CNC for sensing applications in aqueous media. The electrostatic interaction of Pb2+ and Br– ions of CNCs with the terephthalate and Zn2+ ions of MOF-5 do not disturb the structural integrity of the MOFs and the photoluminescence (PL) properties of the CNCs but renders more stability to both the MOFs and CNCs in a water medium. As a proof-of-concept experiment, this water-resistant MOF:CNC probe was successfully validated for the detection of Cd2+ in a water medium. The mechanism of fluorescence enhancement during the sensing of Cd2+ is elucidated using X-ray photoelectron spectroscopy, temperature-dependent, and time-resolved PL studies. The high stability and photoefficiency exhibited by this MOF:CNC composite proves that it is a viable system for applications in aqueous media. [ABSTRACT FROM AUTHOR]

The development of a simple and effective strategy for designing a highly efficient oxygen evolution electrocatalyst is more important to speed up the efficiency-limiting step involved in water electrolysis. The high efficiency of the oxygen evolution reaction (OER) is directly correlated with the class of electrode materials employed. This work reports a series of Co3S4 nanoparticles (Co3S4-2h, Co3S4-3h, and Co3S4-4h) derived from a metal–organic framework (MOF) via a single-step annealing strategy with varying reaction times for the study of OER. During the annealing process, the MOF precursor [Co3(tiron-bpy)2(bpy)-(H2O)8]·(H2O)2 termed as Co-T-BPY directly converted to cobalt sulfide (Co3S4) nanoparticles, along with additional support of the N-doped carbon moiety. Interestingly, variation of reaction time in a fixed temperature condition played a decisive role in optimizing the surface area with huge active sites of the derived products. The optimized Co3S4-3h product needed an overpotential of 285 mV to reach 10 mA cm–2 current density and an acceptable Tafel value (109 mV dec–1) with excellent 14 h of stability performance under harsh alkaline conditions. The OER results are attributed to the combined effect of the Co3S4 phase and N-doped carbon matrix, resulting in substantial stability and high conductivity. Therefore, we believe that the time variation strategy for the preparation of a cobalt-based non-precious electrode material can pave the way in search of an OER-efficient electrocatalyst. [ABSTRACT FROM AUTHOR]

In this study, a series of Al-doped metal-organic frameworks (AlxZr(1−x)-UiO-66) were synthesized through a one-step solvothermal method. Various characterization techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and N2 sorption measurement, suggested that the Al doping was uniform and barely influenced the crystallinity, chemical stability, and thermal stability of the materials. Two cationic dyes, safranine T (ST) and methylene blue (MB), were selected for investigating the adsorption performances of Al-doped UiO-66 materials. Al0.3Zr0.7-UiO-66 exhibited 9.63 and 5.54 times higher adsorption capacities than UiO-66, 498 mg/g and 251 mg/g for ST and MB, respectively. The improved adsorption performance can be attributed to π-π interaction, hydrogen bond, and the coordination between the dye and Al-doped MOF. The pseudo-second-order and Langmuir models explained the adsorption process well, which indicated that the dye adsorption on Al0.3Zr0.7-UiO-66 mostly occurred through chemisorption on homogeneous surfaces. A thermodynamic study indicated the adsorption process was spontaneous and endothermic. The adsorption capacity did not decrease significantly after four cycles. [ABSTRACT FROM AUTHOR]