Cu-metal Organic Framework Research Articles

Elimination of dibenzothiophene from n-hexane by nano-composite membrane containing Cu-MOF in a pervaporation process

In this study, a particular type of thin film nano-composite membranes was prepared and used in the pervaporation process. The membranes were made of polyphenylsulfone and were coated with a thin layer of polydimethylsiloxane containing different amount of Cu-metal–organic framework (MOF) nano-structures. N-hexane containing dibenzothiophene was used as a model fuel. To characterize MOF and the prepared membranes, Fourier transform infrared, X-Ray diffraction, Brunauer–Emmett–Teller, field-emission scanning electron microscopy, water contact angle measurements, and thermogravimetric analysis were used. The effect of parameters such as sulfur content, process temperature, and Cu-MOF concentration on the membrane performance was evaluated. The results indicated that nano-composite membranes demonstrate a much better performance compared to the untreated membrane. The membrane containing 5 wt% Cu-MOF with a contact angle of 97° had more hydrophilic surface and proved the effect of the additive in improving the surface hydrophilicity. This membrane had the highest rate of flux and rejection (0.4 kg/m2 h and 70%, respectively), and the lowest enrichment factor (0.3). As the temperature increased, the flux of M4 membrane (with 5 wt% additive) increased, while the removal efficiency decreased significantly. The optimum temperature for desulfurization in the pervaporation process was obtained (50 °C).

Ultrasonic Assisted Synthesis of Size-Controlled Cu-Metal-Organic Framework Decorated Graphene Oxide Composite: Sustainable Electrocatalyst for the Trace-Level Determination of Nitrite in Environmental Water Samples.

Excess levels of nitrite ion in drinking water interact with amine functionalized compounds to form carcinogenic nitrosamines, which cause stomach cancer. Thus, it is indispensable to develop a simple protocol to detect nitrite. In this paper, a Cu-metal–organic framework (Cu-MOF) with graphene oxide (GO) composite was synthesized by ultrasonication followed by solvothermal method and then fabricated on a glassy carbon (GC) electrode for the sensitive and selective determination of nitrite contamination. The SEM image of the synthesized Cu-MOF showed colloidosome-like structure with an average size of 8 μm. Interestingly, the Cu-MOF–GO composite synthesized by ultrasonic irradiation followed by solvothermal process produce controlled size of 3 μm colloidosome-like structure. This was attributed to the formation of an exfoliated sheet-like structure of GO by ultrasonication in addition to the obvious influence of GO providing the oxygen functional groups as a nucleation node for size-controlled growth. On the other hand, the composite prepared without ultrasonication exhibited 6.6 μm size agglomerated colloidosome-like structures, indicating the crucial role of ultrasonication for the formation of size-controlled composites. XPS results confirmed the presence of Cu(II) in the as-synthesized Cu-MOF–GO based on the binding energies at 935.5 eV for Cu 2p3/2 and 955.4 eV for Cu 2p1/2. The electrochemical impedance studies in [Fe(CN)6]3–/4– redox couple at the composite fabricated electrode exhibited more facile electron transfer than that with Cu-MOF and GO modified electrodes, which helped to utilize Cu-MOF–GO for trace level determination of nitrite in environmental effluent samples. The Cu-MOF–GO fabricated electrode offered a superior sensitive platform for nitrite determination than the Cu-MOF and GO modified electrodes demonstrating oxidation at less positive potential with enhanced oxidation current. The present sensor detects nitrite in the concentration range of 1 × 10–8 to 1 × 10–4 M with the lowest limit of detection (LOD) of 1.47 nM (S/N = 3). Finally, the present Cu-MOF–GO electrode was successfully exploited for nitrite ion determination in lake and dye contaminated water samples.

Ultra-sensitive molecularly imprinted electrochemical sensor for patulin detection based on a novel assembling strategy using Au@Cu-MOF/N-GQDs

This study introduces an innovative procedure for the development of a molecularly imprinted electrochemical sensor for ultra-sensitive and selective detection of patulin. Firstly, the surface of a glassy carbon electrode (GCE) was decorated by nitrogen doped graphene quantum dots (N-GQDs) and AuNPs-functionalized Cu-metal organic framework (Au@Cu-MOF) and then a layer of molecularly imprinted polymer (MIP) was grown on Au@Cu-MOF/N-GQDs/GCE by electropolymerization. Electrochemical techniques were used to characterize and study the electrochemical behavior of the MIP/Au@Cu-MOF/N-GQDs/GCE, which exhibited a stable reference peak of Au@Cu-MOF at −0.11 V after elution of patulin molecules. This peak current density decreased with rebinding of patulin molecules therefore it was considered as indicator signal. The designed MIP sensor presented a wide linear range from 0.001 to 70.0 ng mL−1, and a low detection limit (0.0007 ng mL−1). This newly developed method based on the synergistic effects of N-GQDs and Au@Cu-MOF combined with MIP technique offered outstanding selectivity, sensitivity, stability, and reproducibility. The good accuracy (recovery%, 97.6–99.4) and high precision (RSD%, 1.23–4.61) of this sensing system for analysis of apple juices proved the high potential of it for rapid and low cost determination of patulin compared to chromatographic methods.

Hollow Metal-Organic-Framework-Mediated In Situ Architecture of Copper Dendrites for Enhanced CO2 Electroreduction.

Electrocatalytic reduction of CO2 to a single product at high current densities and efficiencies remains a challenge. However, the conventional electrode preparation methods, such as drop-casting, usually suffer from low intrinsic activity. Herein, we report a synthesis strategy for preparing heterogeneous electrocatalyst composed of 3D hierarchical Cu dendrites that derived from an in situ electrosynthesized hollow copper metal-organic framework (MOF), for which the preparation of the Cu-MOF film took only 5 min. The synthesis strategy preferentially exposes active sites, which favor's the reduction of CO2 to formate. The current density could be as high as 102.1 mA cm-2 with a selectivity of 98.2 % in ionic-liquid-based electrolyte and a commonly used H-type cell.

An enzyme-free ultrasensitive electrochemical immunosensor for calprotectin detection based on PtNi nanoparticles functionalized 2D Cu-metal organic framework nanosheets

In this work, a novel high electro-catalytic material was synthesized using PtNi nanospheres to functionalize two-dimensional (2D) ultrathin Cu-TCPP(Fe) nanosheets (PtNi@Cu-TCPP(Fe)), and was further applied to develop an enzyme-free electrochemical immunosensor for the ultrasensitive determination of calprotectin (CALP). The bimetallic Cu-TCPP(Fe) nanosheets with large surface area and massive accessible active sites permitted multiple PtNi to attach their surface, which not only enhanced the catalytic ability and conductivity for non-enzymatic amplification but also provided the modified active sites for antibody immobilization as signal labels. Upon the dual electro-catalytic activity of Cu-TCPP(Fe) and PtNi towards H2O2 reduction for signal amplification, this proposed sandwich CALP immunosensor exhibited a wide linear range of 200 fg mL−1 ∼ 50 ng mL−1 and a low detection limit of 137.7 fg mL−1. The functionalized MOF nanosheets-based biosensing method offered an enzyme-free signal amplification strategy, which provided great promise for further bioanalysis and clinical study.

Ratiometric electrochemical sensor for accurate detection of salicylic acid in leaves of living plants.

Detection of signal molecules in living plants is of great relevance for precision farming. In this work, to establish a more effective method for monitoring salicylic acid (SA) in the leaves of living plants, a ratiometric electrochemical sensor was fabricated based on a Cu metal–organic framework (Cu-MOF) and carbon black (CB) composite. The Cu-MOF and CB composite was used to catalyze SA oxidation. Ratiometric oxidation current peak intensities ISA/ICu-MOFs were used as the response signal for SA. ISA/ICu-MOFs linearly enhanced with the increase of SA concentration, together with low limits of detection (12.50 μM). Moreover, our sensor is fabricated on a screen-printed electrode (SPE), which is especially suitable for applying to the flat leaves of plants. Using this sensor, the SA level in the leaves of cucumber seedlings was monitored in vivo under salt stress. The proposed sensor is accurate, reliable and practical. This is the first report for developing a ratiometric electrochemical sensor for detecting SA in living plants. Our work can also provide a strategy for in vivo studies on the leaves of plants.

Highly sensitive and selective determination of malathion in vegetable extracts by an electrochemical sensor based on Cu-metal organic framework

This article demonstrates the first application of a copper-based porous coordination polymer (BTCA-P-Cu-CP) as a carbon paste electrode (CPE) modifier for the detection of malathion. The electrochemical behavior of BTCA-P-Cu-CP/CPE was explored using cyclic voltammetry (CV) while chrono-amperometry methods were applied for the analytical evaluation of the sensor performance. Under optimized conditions, the developed sensor exhibited high reproducibility, stability, and wide dynamic range (0.6–24 nM) with the limits of detection and sensitivity equal to 0.17 nM and 5.7 µAnMcm−1, respectively, based on inhibition signal measurement. Furthermore, the presence of common coexisting interfering species showed a minor change in signals (<4.4%). The developed sensor has been applied in the determination of malathion in spiked vegetable extracts. It exhibited promising results in term of fast and sensitive determination of malathion in real samples at trace level with recoveries of 91.0 to 104.4%. (RSDs < 5%, n = 3). A comparison of the two studied techniques showed that the HPLC technique is unable to detect malathion when the concentration is lower than 1.8 µM while 0.006 µM is detected with appropriate RSDs 0.2–5.2% (n = 3) by amperometric method. Due to the high sensitivity and selectivity, this new electrochemical sensor will be useful for monitoring trace malathion in real samples.

Restructuring of Cu2O to Cu2O@Cu-Metal-Organic Frameworks for Selective Electrochemical Reduction of CO2.

Electrochemical reduction of carbon dioxide to hydrocarbons, driven by renewable power sources, is a fascinating and clean way to remedy greenhouse gas emission as a result of overdependence on fossil fuels and produce value-added fine chemicals. The Cu-based catalysts feature unique superiorities; nevertheless, achieving high hydrocarbon selectivity is still inhibited and remains a great challenge. In this study, we report on a tailor-made multifunction-coupled Cu-metal-organic framework (Cu-MOF) electrocatalyst by time-resolved controllable restructuration from Cu2O to Cu2O@Cu-MOF. The restructured electrocatalyst features a time-responsive behavior and is equipped with high specific surface area for strong adsorption capacity of CO2 and abundant active sites for high electrocatalysis activity based on the as-produced MOF on the surface of Cu2O, as well as the accelerated charge transfer derived from the Cu2O core in comparison with the Cu-MOF. These intriguing characteristics finally lead to a prominent performance towards hydrocarbons, with a high hydrocarbon Faradaic efficiency (FE) of 79.4%, particularly, the CH4 FE as high as 63.2% (at -1.71 V). This work presents a novel and efficient strategy to configure MOF-based materials in energy and catalysis fields, with a focus on big surface area, high adsorption ability, andmuch more exposed active sites.

Synergistic effects between Cu metal–organic framework (Cu-MOF) and carbon nanomaterials for the catalyzation of the thermal decomposition of ammonium perchlorate (AP)

In this study, a novel Cu-MOF@Carbon nanomaterial composite was prepared to catalyze the thermal decomposition of ammonium perchlorate (AP). The structure was characterized by using scanning electron microscope (SEM), X-ray energy-dispersive spectrum (EDS), and X-ray diffraction (XRD); the specific surface area was estimated by Brunauer–Emmett–Teller (BET) method; and the pore volumes and pore size distributions were derived from the adsorption branches of isotherms using the Barrett–Joyner–Halenda (BJH) model. And the thermal decomposition behavior was investigated by using differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). The results indicated that all products showed excellent catalytic activity. Among the samples investigated here, Cu-MOF@CNT-rGO exhibited the best catalytic activity, since the high-temperature decomposition peak of AP decreased to 313.8 °C, which is reduced nearly 100 °C than the raw material (409.7 °C). And this was attributed to the high thermal and electrical conductivities of carbon nanomaterials, and the large surface area of both Cu-MOF and carbon nanomaterials. This study provides a new choice to be used as the promising catalysts in modifying the burning performance of AP-based composite propellant.

Ultrafine Pt Nanoparticles and Amorphous Nickel Supported on 3D Mesoporous Carbon Derived from Cu-Metal–Organic Framework for Efficient Methanol Oxidation and Nitrophenol Reduction

The development of novel strategy to produce new porous carbon materials is extremely important because these materials have wide applications in energy storage/conversion, mixture separation, and catalysis. Herein, for the first time, a novel 3D carbon substrate with hierarchical pores derived from commercially available Cu-MOF (metal-organic framework) (HKUST-1) through carbonization and chemical etching has been employed as the catalysts' support. Highly dispersed Pt nanoparticles and amorphous nickel were evenly dispersed on the surface or embedded within carbon matrix. The corresponding optimal composite catalyst exhibits a high mass-specific peak current of 1195 mA mg-1 Pt and excellent poison resistance capacity ( IF/ IB = 1.58) for methanol oxidation compared to commercial Pt/C (20%). Moreover, both composite catalysts manifest outstanding properties in the reduction of nitrophenol and demonstrate diverse selectivities for 2/3/4-nitrophenol, which can be attributed to different integrated forms between active species and carbon matrix. This attractive route offers broad prospects for the usage of a large number of available MOFs in fabricating functional carbon materials as well as highly active carbon-based electrocatalysts and heterogeneous organic catalysts.

A nanoscale Cu-metal organic framework with Schiff base ligand: Synthesis, characterization and investigation catalytic activity in the oxidation of alcohols

Nanostructures of a new copper-based metal-organic framework with a Schiff base ligand as an organic linker, Cu2 (bdda) (OAc)2·1H2O (H2bdda=4,4′-[benzene-1,4-diylbis (methylylidenenitrilo)] dibenzoic acid), was prepared via Ultrasound assisted synthesis and characterized by X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET), inductively coupled plasma atomic emission spectroscopy (ICP-AES), transmission electron microscope (TEM), elemental analysis (CHN) and FT-IR spectroscopy. Catalytic proficiency of this MOF in the oxidation of alcohols was investigated that exhibited efficient and selective activity for the transformation of alcohols to the corresponding carbonyl compounds under the absence of organic solvents. The reusability of the catalyst also was examined, in which the catalyst was reused six times without significant loss of its catalytic efficiency.

TCNQ-doped Cu-metal organic framework as a novel conductometric immunosensing platform for the quantification of prostate cancer antigen

Due to their hierarchical structures and high surface areas, several categories of metal organic frameworks (MOFs) have emerged as next-generation materials for a wide variety of applications, including sensors. However, the poor electrical conductivity is a bottleneck to exploit them in the development of electrochemical sensing devices. In this work, we for the first time report the development and application of tetracyanoquinodimethane (TCNQ)- doped thin films of copper-MOF, Cu3(BTC)2, assembled on gold screen printed electrodes, as an electrochemical sensing platform for highly sensitive detection of a prostate cancer marker. The structural and spectroscopic features of the synthesized material along with the morphological features of the prepared electrodes were characterized with diverse instrumental techniques. Doping the thin films of Cu3(BTC)2 with TCNQ improved the conductance of the base material by nine orders of magnitude (from 10−12 to 10−3S). This conducting platform was modified with antibodies to design an immunosensor for the prostate cancer antigen (PSA). The anti-PSA conjugated TCNQ- Cu3(BTC)2 provided PSA detection in a dynamic linear range of 0.1–100ng/mL to attain a limit of detection at 0.06ng/mL. The above sensor was specific to PSA even in the presence of other proteins. The practical utility of the immunosensor was also demonstrated against some spiked serum samples. The herein proposed TCNQ- Cu3(BTC)2 based detection system involves a robust physical immobilization of the antibodies to facilitate the detection of PSA over a broader and clinically significant concentration range.

Electrochemical investigation of a new Cu-MOF and its electrocatalytic activity towards H2O2 oxidation in alkaline solution

A new Cu metal–organic framework (Cu-MOF), [Cu(adp)(BIB)(H2O)]n (BIB=1,4-bisimidazolebenzene; H2adp=adipic acid), is synthesised under hydrothermal conditions. Single-crystal X-ray analysis reveals a three-dimensional supramolecular architecture with channels originating from two-dimensional layers extended by hydrogen bonds. The cyclic voltammogram of a [Cu(adp)(BIB)(H2O)]n-modified electrode shows a pair of redox peaks at ca. 0.43V in 0.1M NaOH solution corresponding to CuIII(OH)-MOF/CuII(H2O)-MOF couple. The Cu-MOF-modified electrode shows high electrocatalytic activity towards H2O2 oxidation with a linear range from 0.1μM to 2.75μM and a detection limit of 0.068μM. Thus, Cu-MOF is a promising material for H2O2 detection.