Search Results (43)

An electrochemical aptamer sensor for the sensitive detection of aflatoxin B₁ (AFB₁) in corn samples was developed using nanocomposites loaded with copper nanoparticles (CuNPs) on zeolitic imidazolate framework-8 (ZIF-8), which were modified on a glassy carbon electrode (GCE). The CuNPs@ZIF-8 nanocomposites served as modifying materials for electrodes, exhibiting a high specific surface area and excellent compatibility with aptamers, thereby enhancing the electron transfer rate and increasing the aptamer loading and immobilization efficiency. The electrochemical properties before and after modification were investigated and validated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques, while the sensor’s performance was analyzed through quantitative detection via differential pulse voltammetry (DPV). Furthermore, various conditions, including the volume of ZIF-8 dispersion, electrodeposition time of copper nanoparticles, aptamer concentration, and AFB₁ incubation time, were optimized. The results indicated that the sensor exhibited a wide linear range (10.0 to 1.0 × 10⁶ pg/mL), with a lower limit of detection (LOD) of 1.13 pg/mL under optimized conditions, outperforming other reported aptamer sensors. The spiked recoveries in corn samples ranged from 96.663% to 105.72%. In conclusion, this sensor presents a novel solution for low-cost and high-sensitivity detection of AFB₁. Full article

The electrocatalytic decomposition of ammonia represents a promising route for sustainable hydrogen production, yet current systems rely heavily on noble metal catalysts with prohibitive costs and limited durability. A critical challenge lies in developing non-noble electrocatalysts that simultaneously achieve high active site exposure, optimized electronic configurations, and robust structural stability. Addressing these requirements, this study strategically engineered Cu-doped ZIF-8 architectures via in situ growth on nickel foam (NF) substrates through a facile room-temperature hydrothermal synthesis approach. Systematic optimization of the Cu/Zn molar ratio revealed that Cu_0.7Zn_0.3-ZIF/NF achieved optimal performance, exhibiting a distinctive nanoflower-like architecture that substantially increased accessible active sites. The hybrid catalyst demonstrated superior electrocatalytic performance with a current density of 124 mA cm⁻² at 1.6 V vs. RHE and a notably low Tafel slope of 30.94 mV dec⁻¹, outperforming both Zn-ZIF/NF (39.45 mV dec⁻¹) and Cu-ZIF/NF (31.39 mV dec⁻¹). Combined XPS and EDS analyses unveiled a synergistic electronic structure modulation between Zn and Cu, which facilitated charge transfer and enhanced catalytic efficiency. A gas chromatography product analysis identified H₂ and N₂ as the primary gaseous products, confirming the predominant occurrence of the ammonia oxidation reaction (AOR). This study not only presents a noble metal-free electrocatalyst with exceptional efficiency and durability for ammonia decomposition but also demonstrates the significant potential of MOF-derived materials in sustainable hydrogen production technologies. Full article

The development of sensitive and selective methods for detecting pesticide residues has become paramount for ensuring food safety. In this work, a high-performance molecularly imprinted electrochemical sensor based on the composite of Cu-BTC- and FeCo-ZIF-derived N-doped carbon (FeCo@NC), synthesized by pyrolysis and electrodeposition, was developed for Benomyl (BN) detection. The materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). In this sensing system, the Cu-BTC/FeCo@NC composite used as the electrode substrate displayed a large specific surface area, high electronic conductivity, and rich active catalytic sites, demonstrating excellent electrocatalytic ability toward BN oxidation. Meanwhile, Cu-BTC, with its abundant surface functional groups, facilitated strong hydrogen bonding interactions with the imprinted template molecule of 3,4-ethylenedioxythiophene (EDOT), promoting the formation of a uniform molecularly imprinted membrane on the substrate material surface. The introduced MIP-PEDOT could enhance the selective recognition and enrichment of the target BN, leading to an amplified detection signal. Thanks to the synergistic effects between Cu-BTC/FeCo@NC and MIP-PEDOT, the proposed sensor achieved a low detection limit of 1.67 nM. Furthermore, the fabricated sensor exhibited high selectivity, reproducibility, and interference resistance in detecting BN. The method has been successfully applied to the determination of BN in vegetable and fruit samples, indicating its potential for use in practical applications. Full article

Heavy metal pollution has posed a serious threat to the ecological environment and human health. Thus, the development of accurate and effective methods for their detection is crucial. In this study, a novel electrochemical sensor was fabricated to detect Cu²⁺ and Hg²⁺, based on N-doped carbon nanotube-wrapped Ni nanoparticle (Ni@N-CNT) sensing material, which was derived from the pyrolysis of Ni²⁺ doped ZIF-8. For electrode material design, the packaging structure not only protected the encapsulated Ni nanoparticles from electrochemical corrosion in the acid electrolyte but also provided excellent electro-catalytic activity and electrical conductivity by controlling their size. Thanks to the overall performance of the Ni@N-CNT composite, the proposed sensor exhibited excellent analytical performance for Cu²⁺ and Hg²⁺ detection, with ultra-low detection limits of 33.3 ng⋅L⁻¹ and 33.3 ng⋅L⁻¹, respectively. The sensor also demonstrated good repeatability, reproducibility and selectivity. In addition, the method was successfully applied to the electrochemical analysis of Cu²⁺ and Hg²⁺ in actual Chinese cabbage samples with satisfactory recovery, confirming its practical applicability. Full article

Compared to conventional adsorbents, zinc-based metal–organic frameworks (MOFs) such as zeolite imidazolium skeleton-8 (ZIF-8) exhibit enhanced thermal, chemical, and structural stability. Nonetheless, their powdered form results in limited dispersibility in aqueous solutions and a tendency to aggregate, which significantly restricts their utility in adsorption applications. This study reports a green composite aerogel through the in situ mineralization of ZIF-8 onto bacterial cellulose (BC) for the effective removal of toxic metal ions (Cu²⁺) and Congo red (CR) from wastewater. The ZIF@BC composite aerogel was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and specific surface area analysis. The findings indicated that the ZIF-8 produced were evenly distributed across the BC nanonetwork, facilitating effective adsorption of CR and Cu²⁺. The maximum adsorption capacities of the ZIF@BC aerogels were determined to be 397.55 mg/g for CR and 424.80 mg/g for Cu²⁺, as per the Langmuir isotherm. Furthermore, the ZIF-8@BC aerogels demonstrated excellent selectivity and reusability, particularly for CR adsorption. The proposed mechanism for the interaction between the composite aerogel and CR and Cu²⁺ involves electrostatic interactions, hydrogen bonding, π-π bonding, coordination bonding, ion exchange, microchemical precipitation, and pore diffusion. This research offers significant promise for the utilization of MOF powders and highlights substantial industrial potential. Full article

Heavy metal pollution has become an increasingly serious environmental issue, making the detection of heavy metals essential for safeguarding public health and the environment. This review aims to highlight the commonly used methods for detecting heavy metals (such as atomic absorption spectroscopy (AAS), atomic emission spectroscopy (AES), inductively coupled plasma–mass spectrometry (ICP-MS), square-wave anodic stripping voltammetry (SWASV), etc.), with a particular focus on electrochemical detection and electrode modification materials. Metal nanomaterials (such as titanium dioxide (TiO₂), copper oxide (CuO), ZIF-8, MXene, etc.) are emphasized as promising candidates for enhancing the performance of sensors due to their high surface area and excellent catalytic properties. However, challenges such as interference from non-target heavy metal ions and the formation of organometallic complexes with organic compounds can complicate the detection process. To address these issues, two potential solutions have been proposed: the development of advanced algorithms (such as machine learning (ML), back-propagation neural network (BPNN), support vector machines (SVM), random forests (RF), etc.) for signal processing and the use of pretreatment methods (such as Fenton oxidation (FO), ozone oxidation, and photochemical oxidation) to suppress such interferences. This paper aims to review commonly used methods for detecting heavy metals, with a particular emphasis on electrochemical techniques. It will also highlight the challenges faced in these methods, such as interference and sensitivity limitations, and propose innovative solutions, including the use of metal nanomaterials for improved sensor performance and the integration of advanced algorithms and pretreatment techniques to address interference and enhance detection accuracy. Full article

The development of copper-based materials with a high efficiency and low cost is desirable for use in iodine (I₂) remediation. Herein, Cu⁰-nanoparticles-functionalized, ZIF-8 (Zeolite Imidazole Framework-8)-derived, nitrogen-doped carbon composites (Cu@Zn-NC) were synthesized by ball milling and pyrolysis processes. The as-prepared composites were characterized using SEM, BET, XRD, XPS, and FT-IR analyses. The results showed that the morphology of ZIF-8 changed from a leaf-like structure into an irregular structure after the introduction of a copper salt and carbonization. The copper in the pyrolysis samples was mainly in the form of Cu⁰ particles. The presence of an appropriate amount of Cu⁰ particles could increase the specific surface area of Cu@Zn-NC. The subsequent batch adsorption results demonstrated that the as-fabricated composites showed high I₂ adsorption amounts (1204.9 mg/g) and relatively fast dynamics in an iodine–cyclohexane solution when the Cu content was 30% and the pyrolysis temperature was 600 °C, outperforming the other Cu-based materials. The isothermal adsorption followed both Langmuir and Dubinin–Radushkevich isotherm models, while the kinetics of I₂ adsorption followed a pseudo-second-order kinetic model. The activation energy (E_α) of the adsorbent was determined to be 47.2 kJ/mol, according to the Arrhenius equation. According to the experimental and DFT analyses, I₂-Zn interactions and I₂-Cu⁰ chemisorption jointly promoted the elimination of iodine. In general, this study provided an operative adsorbent for the highly effective capture of iodine in solution, which might be worth applying on a large scale. Full article

Gold nanoclusters (AuNCs) have been widely investigated because of their unique photoluminescence properties. However, the applications of AuNCs are limited by their poor stability and relatively low fluorescence. In the present work, we developed nanocomposites (L-Cys-AuNCs@ZIF-8) with high fluorescence and stability, which were constructed by encapsulating the water-dispersible L-Cys-AuNCs into a ZIF-8 via Zn²⁺-triggered growth strategy without high temperature and pressure. The maximum emission wavelength of the L-Cys-AuNCs@ZIF-8 composite was at 868 nm, and the fluorescence intensity of L-Cys-AuNCs@ZIF-8 was nearly nine-fold compared with L-Cys-AuNCs without the ZIF-8 package. The mechanism investigation by fluorescence spectroscopy and X-ray photoelectron spectroscopy showed that L-Cys-AuNCs@ZIF-8 impeded ligand rotation, induced energy dissipation, and diminished the self-quenching effect, attributing to the spatial distribution of L-Cys-AuNCs. Based on the high fluorescence efficiency of L-Cys-AuNCs@ZIF-8, a “signal off” detective platform was proposed with copper ions as a model analyte, achieving a sensitive detection limit of Cu²⁺ at 16.7 nM. The quenching mechanism was confirmed, showing that the structure of the L-Cys-AuNCs@ZIF-8 nanocomposites was collapsed by the addition of Cu²⁺. Attributing to the strong adsorption ability between copper ions and pyridyl nitrogen, the as-prepared L-Cys-AuNCs@ZIF-8 was shown to accumulate Cu²⁺, and the Zn²⁺ in ZIF-8 was replaced by Cu²⁺. Full article

Metal air batteries have gradually attracted public attention due to their advantages such as high power density, high energy density, high energy conversion efficiency, and clean and green products. Reasonable design of oxygen reduction reaction (ORR) catalysts with high cost-effectiveness, high activity, and high stability is of great significance. Metal organic frameworks (MOFs) have the advantages of large specific surface area, high porosity, and designability, which make them widely used in many fields, especially in catalysis. This paper starts with regulating and optimizing the composition and structure of MOFs. A series of N, S co-doped electrocatalysts FeCuS-N-C were prepared by two high-temperature pyrolysis processes using N-doped carbon hollow nanorods derived from ZIF-8 as the substrate. The one-dimensional nanorod material derived from this MOF exhibits excellent electrocatalytic ORR performance (Eonset = 0.998 V, E_1/2 = 0.874 V). When used as the air cathode catalyst for zinc air batteries and assembled into liquid ZABs, the battery discharge curve was calculated and found to have a maximum power density of 142.7 mW cm⁻², a specific capacity of 817.1 mAh gZn⁻¹, and a cycling stability test of over 400 h. This study provides an innovative approach for designing and optimizing non-precious metal catalysts for zinc air batteries. Full article

Microwave plasma-driven nitrogen fixation can occur at atmospheric pressure without complex processing conditions. However, this method still faces the challenge of high energy consumption and low production. Combined plasma–catalyst systems are widely used to increase production and reduce energy consumption in nitrogen fixation. However, the efficacy of currently used catalysts remains limited. In this paper, the metal–organic framework materials (MOFs) copper benzene-1,3,5-tricarboxylate (Cu-BTC) and zeolitic imidazolate framework-8 (ZIF-8) are combined with atmospheric microwave plasma for nitrogen fixation. The experimental results show that they have a better catalytic effect than the ordinary catalyst zeolite socony mobil-5 (ZSM-5). The maximum nitrogen oxide concentration reaches 33,400 ppm, and the lowest energy consumption is 2.05 MJ/mol. Compared to no catalyst, the production of nitrogen oxides (NO_x) can be increased by 17.1%, and the energy consumption can be reduced by 14.6%. The stability test carried out these catalysts demonstrates that they have a stable performance within one hour. To the knowledge of the authors, this is the first effort to study the synergistic effects of atmospheric microwave plasma and MOFs on nitrogen fixation. This study also introduces a potentially eco-friendly approach to nitrogen fixation, characterized by its low energy consumption and emissions. Full article

In the critical domain of wastewater treatment, the development of cost-effective, durable, and recyclable adsorbents with high adsorption capacities remains a significant challenge. This study introduces a novel magnetic bimetallic Metal–Organic Framework (MOF) adsorbent, MZIF-67-Co/Cu, doped with copper ions. The MZIF-67-Co/Cu adsorbent was successfully synthesized and structurally characterized, demonstrating remarkable selectivity for removing methyl orange (MO) from water. This high selectivity is attributed to the adsorbent’s high porosity and Lewis base properties at the coordinating metal ion center. The incorporation of Cu ions significantly enhances the porous architecture and increases the number of metal adsorption sites, leading to an impressive maximum MO adsorption capacity of 39.02 mg/g under optimized conditions (0.5 g/L adsorbent concentration, pH 3.0, 250 rpm agitation speed, adsorption time > 10 min). The adsorption kinetics closely follow the pseudo-second-order model, and the isotherm data fit well with the Langmuir model. The primary adsorption mechanisms involve electrostatic attraction and mesoporous interaction. This study highlights MZIF-67-Co/Cu as a highly efficient adsorbent with magnetic recovery capabilities, positioning it as a promising candidate for addressing critical issues in wastewater treatment. Full article

Metal–organic frameworks (MOFs) receive wide attention owing to their high specific surface area, porosity, and structural designability. In this paper, ZC-Ru and ZC-Cu electrodes loaded with monatomic Ru and Cu doped with nitrogen were prepared by pyrolysis, ion impregnation, and carbonization process using ZIF-8 synthesized by static precipitation as a precursor. ZC-Cu has a high specific surface area of 859.78 m² g⁻¹ and abundant heteroatoms O (10.04%) and N (13.9%), showing the specific capacitance of 222.21 F g⁻¹ at 0.1 A g⁻¹ in three-electrode system, and low equivalent series resistance (Rct: 0.13 Ω), indicating excellent energy storage capacity and electrical conductivity. After 10,000 cycles at 1 A g⁻¹ in 6 M KOH electrolyte, it still has an outstanding capacitance retention of 99.42%. Notably, symmetric supercapacitors ZC-Cu//ZC-Cu achieved the maximum power density and energy density of 485.12 W·kg⁻¹ and 1.61 Wh·kg⁻¹, respectively, positioning ZC-Cu among the forefront of previously known MOF-based electrode materials. This work demonstrates the enormous potential of ZC-Cu in the supercapacitor industry and provides a facile approach to the treatment of transition metal. Full article

Bisphenol A (BPA), representing a class of organic pollutants, finds extensive applications in the pharmaceutical industry. However, its widespread use poses a significant hazard to both ecosystem integrity and human health. Advanced oxidation processes (AOPs) based on peroxymonosulfate (PMS) via heterogeneous catalysts are frequently proposed for treating persistent pollutants. In this study, the degradation performance of BPA in an oxidation system of PMS activated by transition metal sites anchored nitrogen-doped carbonaceous substrate (M-N-C) materials was investigated. As heterogeneous catalysts targeting the activation of peroxymonosulfate (PMS), M-N-C materials emerge as promising contenders poised to overcome the limitations encountered with traditional carbon materials, which often exhibit insufficient activity in the PMS activation process. Nevertheless, the amalgamation of metal sites during the synthesis process presents a formidable challenge to the structural design of M-N-C. Herein, employing ZIF-8 as the precursor of carbonaceous support, metal ions can readily penetrate the cage structure of the substrate, and the N-rich linkers serve as effective ligands for anchoring metal cations, thereby overcoming the awkward limitation. The research results of this study indicate BPA in water matrix can be effectively removed in the M-N-C/PMS system, in which the obtained nitrogen-rich ZIF-8-derived Cu-N-C presented excellent activity and stability on the PMS activation, as well as the outstanding resistance towards the variation of environmental factors. Moreover, the biological toxicity of BPA and its degradation intermediates were investigated via the Toxicity Estimation Software Tool (T.E.S.T.) based on the ECOSAR system. Full article

A major strategy to combat implant-associated infections is to develop implant coatings with intrinsic antibacterial activity. Since hydroxyapatite (HAp) coatings and antibiotic administration are commonly used in clinical settings, developing HAp-coated implants with localized antibiotic-releasing properties has attracted popularity. Considering the antibacterial metal species (Ag, Zn, Cu, etc.) in metal–organic frameworks and their drug delivery capacity, in this study, a gentamicin-loaded zeolitic imidazolate framework-8 nanolayer was deposited on a plasma-sprayed HAp coating (HAp/ZIF-8@Gent), which served as a Gent and Zn²⁺ reservoir. The investigation on the binding interaction between ZIF-8 and HAp indicated that the growth of ZIF-8 was through a Zn²⁺ seed layer on the HAp coating via an adsorption–replacement mechanism, instead of simple physical adsorption. The HAp/ZIF-8@Gent coating exhibited a sustained drug-release property, and the cumulative concentration of released Gent reached 239.8 ± 7.1 μg/mL on day 8. Compared to the HAp-Zn and HAp/ZIF-8 coatings, the HAp/ZIF-8@Gent coating exhibited significantly higher antibacterial activity against E. coli. This was ascribed to the combined antibacterial effects of Zn²⁺ and Gent. The cytocompatibility of the HAp/ZIF-8@Gent coating was confirmed via cell proliferation. Above all, the ZIF-8-modified HAp coating with localized delivery of Gent and Zn²⁺ possessed excellent antibacterial activity and acceptable cytocompatibility, showing potential in mitigating implant-associated infections. Full article

This study investigates electrospun fibers of metal-organic frameworks (MOFs), particularly CuBTC and ZIF-8, in polyacrylonitrile (PAN) for the solid-phase extraction (SPE) of Tamoxifen (TAM) and its metabolites (NDTAM, ENDO, and 4OHT) from human blood plasma. The focus is on the isolation, pre-concentration, and extraction of the analytes, aiming to provide a more accessible and affordable breast cancer patient-monitoring technology. The unique physicochemical properties of MOFs, such as high porosity and surface area, combined with PAN’s stability and low density, are leveraged to improve SPE efficiency. The study meticulously examines the interactions of these MOFs with the analytes under various conditions, including elution solvents and protein precipitators. Results reveal that ZIF-8/PAN composites outperform CuBTC/PAN and PAN alone, especially when methanol is used as the protein precipitator. This superior performance is attributed to the physicochemical compatibility between the analytes’ properties, like solubility and polarity, and the MOFs’ structural features, including pore flexibility, active site availability, surface polarity, and surface area. The findings underscore MOFs’ potential in SPE applications and provide valuable insights into the selectivity and sensitivity of different MOFs towards specific analytes, advancing more efficient targeted extraction methods in biomedical analysis. Full article