Zeolitic Imidazolate framework-L Research Articles

MnOx-decorated MOF-derived nickel-cobalt bimetallic phosphide nanosheet arrays for overall water splitting.

Exploring non-noble metal dual-functional electrocatalysts with high activity and stability for water splitting is highly desirable. In this study, using zeolitic imidazolate framework-L (ZIF-L) nanoarrays as the precursor, manganese oxide-decorated porous nickel-cobalt phosphide nanosheet arrays have been prepared on nickel foam (denoted as MnOx/NiCoP/NF) through cation etching, phosphorization and electrodeposition, which are utilized as an efficient dual-functional electrocatalyst for overall water splitting. The hierarchical porous nanosheet arrays provide abundant active sites for the electrochemical process, while the MnOx modification induces strong interfacial interaction, benefiting charge transfer. Thus, the MnOx/NiCoP/NF exhibits excellent electrocatalytic activity toward the hydrogen evolution reaction (HER, overpotential of 93 mV at 10 mA cm-2), oxygen evolution reaction (OER, overpotential of 240 mV at 10 mA cm-2) and overall water splitting (cell voltage of 1.59 V at 10 mA cm-2). Furthermore, it shows superior stability during continuous overall water splitting for 200 h. This work provides a simple and effective approach for developing efficient non-noble metal dual-functional catalysts for overall water splitting.

Fabrication and performance evaluation of aramid laminated fabrics incorporated with silica composite aerogel for protective clothing

In recent years, researchers have made efforts to promote the thermal protection capabilities of firefighting suits in response to frequent fire accidents. In this paper, a novel silica/aramid nonwoven fabric (SiO2/AF) aerogel composite was prepared by combining AF and SiO2 aerogel using the sol-gel method and dip coating technology. Polyimide (PI) and zeolitic imidazolate framework-L (ZIF-L) were used as insulation reinforcement materials to fabricate four types of laminated fabrics, namely, the outer layer + waterproof breathable layer + different insulation layers (AF, SiO2/AF, 0.8 % SiO2/AF/PI and 0.12 % SiO2/AF/ZIF-L, respectively). In addition, the fireman uniform was taken as the control group. The results showed that the insulation performance of the composite fabrics was better than that of the control group, and the outer layer + waterproof breathable layer+0.12 % SiO2/AF/ZIF-L laminated fabric exhibited the lowest thermal conductivity (0.038 W/(m·K)), best thermal radiation protective performance (RPP) (246.04 kW/m2) and excellent wear resistance (mass loss rate 0.46 %). This significant work will open up broad prospects for the applications of SiO2/AF composites in the area of heat-resistant clothing.

Evolution of Local Structure and Pore Architecture during Zeolitic Imidazolate Framework-L to Zeolitic Imidazolate Framework-8 Phase Transformation Investigated Using Raman, Extended X-ray Absorption, and Positron Annihilation Lifetime Spectroscopy

Evolution of Local Structure and Pore Architecture during Zeolitic Imidazolate Framework-L to Zeolitic Imidazolate Framework-8 Phase Transformation Investigated Using Raman, Extended X-ray Absorption, and Positron Annihilation Lifetime Spectroscopy

Zeolitic imidazolate framework-L loaded on melamine foam for removal tetracycline hydrochloride from water.

Zeolitic imidazolate framework-L/melamine foam (ZIF-L/MF) is fabricated by an in situ growth method to treat the tetracycline hydrochloride in wastewater. The results show that a large amount of leaf-like ZIF-L is vertically grown on the MF surface. ZIF-L/MF exhibits well adsorption performance with a maximum adsorption ability of 1346mg/g. The pseudo-second-order kinetic model and the Langmuir isotherm model are used to describe the adsorption process well. In addition, the influences of pH and coexisting ions are studied. According to the experimental data and analysis, the adsorption mechanisms may involve H-bonding, π-π interaction, and weak electrostatic interaction. A dynamic adsorption experiment is also performed, and the results show that the time required to achieve the same removal efficiency as static adsorption is reduced by half. This work shows that the obtained ZIF-L/MF has practical applications in antibiotic adsorption.

In-situ incorporation of halloysite nanotubes with 2D zeolitic imidazolate framework-L based membrane for dye/salt separation

Layered assembled membranes of 2D leaf-like zeolitic imidazolate frameworks (ZIF-L) nanosheets have received great attention in the field of water treatment due to the porous structure and excellent antibacterial ability, but the dense accumulation on the membrane surface and the low permeate flux greatly hinder their application. Herein, we synthesized mHNTs (modified halloysite nanotubes)/ZIF-L nanocomposites on modified mHNTs by in situ growth method. Interestingly, due to the different size of mHNTs and ZIF-L, mHNTs were packed in ZIF-L nanosheets. The hollow mHNTs provided additional transport channels for water molecules, and the accumulation of the ZIF-L nanosheets was decreased after assembling mHNTs/ZIF-L nanocomposites into membrane by filtration. The prepared mHNTs/ZIF-L membrane presented high permeate flux (59.6 L·m−2·h−1), which is 2–4 times of the ZIF-L membranes (14.8 L·m−2·h−1). Moreover, mHNTs/ZIF-L membranes are intrinsically antimicrobial, which exhibit extremely high bacterial resistance. We provide a controllable strategy to improve 2D ZIF-L assembles, and develops novel membranes using 2D package structure as building units.

MOF-Derived Iron-Cobalt Bimetallic Selenides for Water Electrolysis with High-Efficiency Oxygen Evolution Reaction.

Highly active and stable oxygen evolution reaction (OER) electrocatalysts for water electrolysis are currently in high demand. Herein, a rationally designed three-dimensional (3D) CoFe selenide porous array (Fe-CoSe PA) is synthesized through ion exchange from zeolitic imidazolate framework-L (ZIF-L) nanoarray, followed by a facile selenization under hydrothermal conditions for OER electrocatalysis. During the OER process, the surface of Fe-CoSe PA is rapidly oxidized to CoFe oxides/hydroxides, which prevents the inner layer from being oxidized. Benefiting from the high porosity, abundant active sites, and the high conductivity of inner Fe-CoSe, Fe-CoSe PA exhibits excellent OER performance, with an overpotential of 285 mV at a current density of 10 mA cm-2, and a small Tafel slope of 68 mV dec-1, as well as high stability under 50 h of continuous testing. The present work could provide a facile route for fabricating 3D porous selenides for highly efficient OER catalysis.

Application of bacterial nanocellulose decorated with zeolitic imidazolate framework (ZIF-L) as a platform for food freshness monitoring

Recently, the food freshness indicator (FFI) has garnered great interest from consumers and food producers. A novel FFI based on bacterial nanocellulose (BNC)/zeolitic imidazolate framework-L (ZIF-L) and grape anthocyanins was developed and characterized using field emission scanning electron microscopy, Fourier-transform infrared, X-ray diffraction, water contact angle, and BET techniques. The results confirmed that the BNC fibrils were decorated by in situ growth of ZIF-L, with a 3D flower-shaped structure and randomly multiple sharp-edged petals, and hydroxyl and oxygenated heterocycle aromatic ring functional groups on its surface. The reversibility, color stability performance, and moisture sorption of FFI were studied and its applicability in a two-layer arrangement as a visual freshness monitoring of shrimp and minced beef was evaluated. The FFI was able to distinguish (ΔE > 5) the fresh, medium fresh, and spoiled minced meat and shrimp visually during 10 and 4 days of storage at 4 °C, respectively. Also, monitoring of food chemical and microbiological parameters approved the correlation of food spoilage with the color parameters of FFI. These results confirmed the function of ZIF-L in the fabrication of highly pH-sensitive food intelligent packaging material.

Two-dimensional hollow carbon skeleton decorated with ultrafine Co3O4 nanoparticles for enhanced lithium storage

Transition metal oxides have shown high theoretical capacities as anode materials and have been considered as high potential materials to substitute graphite for composing new generations of lithium-ion batteries (LIBs). However, the considerable volume changes of transition metal oxide materials during practical processes have limited their applications. Herein, we report a simple approach to construct a two-dimensional (2D) hollow carbon skeleton decorated with ultrafine Co3O4 nanoparticles (Co3O4/C). This composite is derived from a leaf-like zeolitic imidazolate framework-L (ZIF-L (Co)) via etching coordination using tannic acid (TA). The Co3O4/C has a unique structure consisting of 2D carbon skeleton, ultrafine Co3O4 nanoparticle, and open channel, which can accelerate electron transport, alleviate volume change, and facilitate ion diffusion. Benefiting from these features, the LIBs assembled using Co3O4/C as anode material exhibits superior reversible cycle performance and impressive rate property. This study provides an efficient strategy for implementing transition metal oxide-based composites for energy storage applications.

A colorimetric assay for cholesterol based on the encapsulation of multienzyme in leaf-shape crossed ZIF-L

The serum cholesterol level is an important indicator of healthy and there is a great necessity for frequent cholesterol monitoring to some cardiovascular-related diseases, which puts forward higher requirements for point-of-care testing (POCT) of cholesterol. In this work, a cascade catalytic system of cholesterol is developed by encapsulation of cholesterol oxidase (ChOx) and PdCuAu nanoparticles into zeolitic imidazolate framework-L (ChOx/PCA@ZIF-L). Results indicate that ZIF-L carrier can significantly increase the catalytic activity of single or multiple enzymes, due to its high loading capacity and efficient molecular transport. Under the optimal conditions, the absorbance of reaction system performs linear relationships with the concentration of cholesterol in two intervals from 0.0005 mmol/L to 1.0000 mmol/L, with a limit of detection of 0.2176 µmol/L. The proposed colorimetric strategy based on ChOx/PCA@ZIF-L performs a good agreement with the results provided by chemiluminescence method for the serum cholesterol detection. Interestingly, a simple paper-based sensing system is constructed through a pre-reaction-transfer operation, which gets rid of the complex pre-processing requirements of traditional operations on filter paper. The presented strategy allows for the sensitive, convenient, costless assay of serum cholesterol, and paves a new way to design the POCT device for daily monitoring of healthy.

In Situ Growth of Zeolitic Imidazolate Framework-L in Macroporous PVA/CMC/PEG Composite Hydrogels with Synergistic Antibacterial and Rapid Hemostatic Functions for Wound Dressing.

Although many advances have been made in medicine, traumatic bleeding and wound infection are two of the most serious threats to human health. To achieve rapid hemostasis and prevent infection by pathogenic microbes, the development of new hemostatic and antibacterial materials has recently gained significant attention. In this paper, safe, non-toxic, and biocompatible polyvinyl alcohol (PVA); carboxymethyl cellulose (CMC), which contains several carboxyl and hydroxyl groups; and polyethylene glycol (PEG), which functions as a pore-forming agent, were used to prepare a novel PVA/CMC/PEG-based composite hydrogel with a macroporous structure by the freeze-thaw method and the phase separation technique. In addition, a PVA/CMC/PEG@ZIF-L composite hydrogel was prepared by the in situ growth of zeolitic imidazolate framework-L (ZIF-L). ZIF-L grown in situ on hydrogels released Zn2+ and imidazolyl groups. They elicited a synergistic antibacterial effect in hemostasis with PVA and CMC, rendering the PVA/CMC/PEG@ZIF-L hydrogel with a good antibacterial effect against Staphylococcus aureus. At the same time, the macroporous structure enabled the rapid release of Zn2+ and imidazolyl groups in ZIF-L and promoted cell proliferation at an early stage, enhancing the coagulation efficiency. A rat liver injury model was used to confirm its rapid hemostasis capacity.

Insertion of Hemin into Metal-Organic Frameworks: Mimicking Natural Peroxidase Microenvironment for the Rapid Ultrasensitive Detection of Uranium.

Constructing enzyme-like active sites in mimic enzyme systems is critical for achieving catalytic performances comparable to natural enzymes and can shed light on the natural development of enzymes. In this study, we described a specific hemin-based mimetic enzyme, which was facilely synthesized by the assembly of zeolitic imidazolate framework-l (ZIF-l) and hemin. The obtained hemin-based mimetic enzyme (denoted as ZIF-l-hemin) displayed enhanced peroxidase activity compared to free hemin in solution. Such excellent activity originated from the ZIF-l framework mimicking the active site cavity microenvironment of horseradish peroxidase in terms of axially coordinated histidine and distal histidine. Additionally, the constructed peroxidase mimetic was extremely resistant to a variety of severe circumstances that would normally denature natural enzymes. These characteristics made ZIF-l-hemin a potential platform for the colorimetric sensor of uranium (UO22+) with wide linear ranges (0.25-40 μM) and low limits of detection (0.079 μM). Moreover, the detection mechanism demonstrated that the coordination of uranyl ion with imidazole of ZIF-l-hemin reduced the catalytic efficiency of ZIF-l-hemin. The current work not only proposed a novel approach for fabricating artificial peroxidase but also offered facile colorimetric methods for selective radionuclide detection.

Metal-organic framework (MOF)-based slippery liquid-infused porous surface (SLIPS) for purely physical antibacterial applications

Medical device-associated infections, caused by bacterial adhesion and biofilm formation, remain a leading threat to public healthcare due to continuous emergence of drug-resistant pathogens. Slippery liquid-infused porous surface (SLIPS) is deemed as a promising mean to reduce colonization of bacteria by exceptional repellency property. However, such inert and mono-functional surface becomes helpless once bacterial adhesion occurs. Here, we report a zeolitic imidazolate framework-L (ZIF-L)-based SLIPS (ZLS) with both anti-biofouling and bactericidal activity that all performances are derived from purely physical interactions. Assembled on various substrates, the porous ZIF-L layer is not only the foundation for constructing SLIPS, but exhibits the mechanical bactericidal activity. Fabricating on the catheters, the ZLS exhibit good biocompatibility and can be utilized in a mice subcutaneous implanted model of infection in vivo without inducing the inflammatory response. Thus, we anticipate that the ZLS could provide a new insight into multifunctional and bactericide-free antibacterial surface modifications.

Zeolitic imidazolate framework-L-assisted synthesis of inorganic and organic anion-intercalated hetero-trimetallic layered double hydroxide sheets as advanced electrode materials for aqueous asymmetric super-capacitor battery

Fine-tuning the interlayer space and composition of the layered double hydroxide (LDH) is a promising strategy to obtain high-performance battery-type electrode materials for super-capacitor battery. In this work, a series of two-dimensional (2D) porous hetero-trimetallic Zinc-Nickel-Cobalt LDHs sheets intercalated with nitrate anion and different Zn/Ni ratios (ZnxNi1-xCo-LDH-NO3–, x = 0, 0.25, 0.5, 0.75, and 1.0) are firstly synthesized through a Zeolitic imidazolate framework-L (ZIF-L)-assisted co-precipitation reaction and ion etching procedure. Among which, the Zn0.25Ni0.75Co-LDH-NO3– electrode, with a Zn/Ni ratio of 1:3, provides a high specific capacity (275 mAh g−1 at 1 A g−1). To further tune the interlayer space, Zn0.25Ni0.75Co-LDH-BA–/AA– (BA– = benzoate anion and AA– = acetate anion) sheets intercalated with BA– or AA– are synthesized by an anion-exchange method. A super-capacitor battery device (Zn0.25Ni0.75Co-LDH-BA–//activated carbon) using Zn0.25Ni0.75Co-LDH-BA– as the positive electrode can achieve a high energy density (51.8 Wh kg−1 at 789 W kg−1) and superb durability (94.6% over 10,000 cycles). This work can shed light on regulating the interlayer space of LDHs for advanced electrochemical energy storage applications.

Two-Dimensional Metal–Organic Frameworks with Unique Oriented Layers for Oxygen Reduction Reaction: Tailoring the Activity through Exposed Crystal Facets

Two-Dimensional Metal–Organic Frameworks with Unique Oriented Layers for Oxygen Reduction Reaction: Tailoring the Activity through Exposed Crystal Facets

Fabrication of titanium incorporation into zeolitic imidazolate framework-L on fabric carrier for visible-light driven photocatalytic antibacterial activity

The development of metal–organic frameworks (MOFs) as a nanoplatform for emerging antibacterial agents has gained great attention. In this work, TiO2 nanoparticles in-situ incorporated in zeolitic imidazolate framework-L (ZIF-L) successfully grow on the non-textile fabric substrate as a novel antibacterial composite ZIF-L@TiO2/fabric with improved visible-light driven antibacterial activity. The morphology and composition of the as-prepared antibacterial composite are characterized via SEM, TEM, XRD, and XPS analysis. The material with high light use efficiency can generate more reactive oxygen species (ROS) under light irradiation than that in dark, which suggests the synergistic effect between TiO2 nanoparticles and ZIF-L in the visible region. Correspondingly, ZIF-L@TiO2/fabric exhibits outstanding antibacterial effect against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), which can also be verified by the Leica SP5 laser scanning confocal microscope (LSCM) results. Furthermore, the possible antibacterial mechanism is proposed. Under visible light irradiation, the synergy of TiO2 nanoparticles and ZIF-L is in favor of producing hydroxyl radical (·OH) and superoxide radicals (·O2−) that directly leads to the death of bacteria. The sufficient antibacterial activity of ZIF-L@TiO2/fabric (over 95% after six antibacterial assay cycles) ensures the long-term use of the material. At this point, the newly synthesized material gives new sight on preparing other MOFs based composites with photocatalytic antibacterial effect for bacterial issues.

CeO2 decorated on Co-ZIF-L-derived nickel-cobalt sulfide hollow nanosheet arrays for high-performance supercapacitors.

Transition metal sulfides have been widely explored as electrode materials for supercapacitors. Unfortunately, the slow redox reaction kinetics and severe volume changes during charge/discharge result in compromised electrochemical performance. In this work, a nickel-cobalt sulfide hollow nanosheet array decorated with cerium oxide nanoparticles (NiCoS/CeO2) has been constructed using a cobalt zeolitic imidazolate framework-L as the template coupled with subsequent solvothermal synthesis. Benefiting from the advantages of the hollow and hierarchical NiCoS nanosheets with a large number of accessible active sites and fast charge transport pathways, as well as CeO2 layers with rich oxygen vacancies and strong interaction between NiCoS and CeO2, NiCoS/CeO2 exhibits a high specific capacity of 1278.1 C g-1 (1 A g-1), which is approximately 1.9 times that of NiCoS. The asymmetric supercapacitor assembled using NiCoS/CeO2 and activated carbon shows an excellent storage capability (34.9 W h kg-1 at 850.0 W kg-1) and an impressive cycle life (91.9% capacitance retention after 10 000 charge and discharge cycles at 10 A g-1).

2Dleaf-like ZIF-L decorated with multi-walled carbon nanotubes as electrochemical sensing platform for sensitively detecting thiabendazole pesticide residues in fruit samples.

Excessive use of pesticides in modern agriculture results in large amounts of pesticide residues in agricultural production, greatly threatening human health. Herein, novel two-dimensional leaf-like zeolitic imidazolate framework-L decorated with multi-walled carbon nanotubes (MWCNTs/ZIF-L) was prepared by a facile solvent way and exploited as electrode material for sensitive electrochemical sensing of thiabendazole (TBZ). Two-dimensional ZIF-L presents high surface area, large pore volume, and abundant active sites, which exhibits high enrichment ability towards TBZ molecules, while the MWCNTs interspersed on ZIF-L can prominently enhance the electron transport capability and improve the electrocatalytic activity for TBZ oxidation. Due to the intriguing synergy between the components, the MWCNTs/ZIF-L-based electrochemical sensor reveals a limit of detection (LOD) of 6.0nmol·L-1, which is lower than that reported in most literatures. Additionally, satisfactory reproducibility and repeatability, long-term stability, and excellent selectivity are acquired. The proposed method was also applied for the detection of TBZ in apple and orange samples with acceptable recoveries.

Effects of operating parameters on cadmium removal for wastewater treatment using zeolitic imidazolate framework-L/graphene oxide composite

Water pollution due to heavy metal contamination has become a critical environmental issue. Thus, effective treatment for polluted water, such as simple adsorption to remove heavy metals, is gaining importance. Towards this end, zeolitic imidazolate framework-L (ZIF-L) with graphene oxide (GO) was successfully incorporated in the synthesis of novel ZIF-L/GO 20 and ZIF-L/GO 50 adsorbents using 20% and 50% loading percentages of GO, respectively, with ultrapure water as the solvent. The morphologies of ZIF-L changed to a flower-like structure with the introduction of 20% GO and turned into smaller irregular shapes when 50% GO was added. These novel adsorbents have demonstrated high adsorption capacities for Cd(II) adsorption at 172.42 mg/g (ZIF-L/GO 20) and 188.68 mg/g (ZIF-L/GO 50), with the optimum dosage of 0.2 g/L of adsorbents. The adsorption isotherms fit Langmuir isotherm, which suggested that adsorption occurred through uniform and monolayer sorption on the surface sites. The electrostatic attraction between the cationic Cd(II) and negatively charged surface played a crucial role as the main pathway in Cd(II) adsorption. Based on the investigated kinetic models, Cd(II) adsorption had a better correlation with the pseudo-second-order kinetic model, which showed that chemisorption occurred during the Cd(II) removal process. The findings of this study revealed that ZIF-L/GO has the potential of becoming the perfect adsorbent for cadmium removal from aqueous solutions.

Fabrication of cross-like ZIF-L structures with water repellency and self-cleaning property via a simple in-situ growth strategy

Inspired by the “lotus effect’’, more and more attention has been paid to the water repellent and self-cleaning surface. Due to its excellent properties, Mg alloy is considered to be one of the most promising engineering materials so far. However, the humid and corrosive environment makes Mg alloy susceptible to corrosion, which greatly limits its wide application. So it is very necessary to improve the properties of Mg alloy through surface treatment. Because of good chemical stability, thermostability and easy preparation, Zeolitic Imidazolate Frameworks (ZIFs) materials have been applied in the field of superhydrophobicity. In addition, in-situ growth has advantages of simple method, convenient operation and no need for expensive experimental equipment. Therefore, in this work, the superhydrophobic coating with cross-like Zeolitic Imidazolate Framework-L (ZIF-L) structure is fabricated on Mg alloy surface via a simple in-situ growth and low energy modification. The superhydrophobic ZIF-L coating on the Mg alloy substrate has excellent water repellency and self-cleaning property, and the stability test results show that it has good performance in thermostability and durability. Besides, the coating keeps superhydrophobic state after being immersed in an alkaline solution for 112 h, showing excellent resistance to alkaline solution. Therefore, the superhydrophobic coating prepared in this work can expand the application of Mg alloy in different service environments and provide a novel way for Mg alloy applying into more fields.

Zeolitic imidazolate framework-L incorporated graphene oxide hybrid for cadmium removal

Abstract The removal of cadmium from wastewater is crucial to avoid its harmful effects on the ecosystem. Thus, in this study, novel composites were prepared by in situ synthesis of zeolitic imidazolate framework-L (ZIF-L) incorporated with graphene oxide (GO) of different loading ratios to produce ZIF-L/GO 20 and ZIF-L/GO 50. The adsorbents were characterized using X-ray Diffractometer (XRD), Fourier-transform Infrared Spectroscopy (FT-IR), and Scanning Electron Microscopy (SEM). The effects of Cd(II) adsorption with respect to the initial pH solution, adsorbent dosage, initial Cd(II) concentration, and contact time were investigated. Both ZIF-L/GO 20 and ZIF-L/GO 50 showed superior performance in removing Cd(II) as compared with ZIF-L (62.32% within 160 min), which were 64.35% and 70.41% within 60 min and 180 min, respectively. The optimum dosage obtained was 0.2 g/L for the removal of 100 mg/L Cd(II) synthetic wastewater. The protruding grains of flower-like ZIF-L/GO 20 allowed for faster adsorption time, whereas the smaller size of irregular shapes ZIF-L/GO 50 increased the surface area for higher adsorption capacity. Also, the adsorption of Cd(II) had fitted well with pseudo-second-order kinetic model and Langmuir isotherm. The Langmuir maximum adsorption capacities for ZIF-L, ZIF-L/GO 20, and ZIF-L/GO 50 were 163.93, 172.42, and 188.68 mg/g, respectively. The novel adsorbents ZIF-L/GO 20 and ZIF-L/GO 50 showed promising performance in the removal of Cd(II) ion from the aqueous solution.