ZIF-67 filled PDMS mixed matrix membranes for recovery of ethanol via pervaporation

Nickel-Cobalt Bimetal Hierarchical Hollow Nanosheets for Efficient Oxygen Evolution in Seawater

The electrochemical splitting of seawater is promising but also challenging for sustainable hydrogen gas production. Herein, ZIF-67 nanosheets are grown on nickel foam and then etched by Ni2+ in situ to obtain a hierarchical hollow nanosheets structure, which demonstrates outstanding OER performance in alkaline seawater (355 mV at 100 mA cm-2). Diven by a silicon solar panel, an overall electrolysis energy efficiency of 62% is achieved at a high current of 100 mA cm-2 in seawater electrolytes. This work provides a new design route for improving the catalytic activity of metal organic framework materials.

Synergistic photoinduced charge transfer resonance from porous ZIF-67 decorated violet phosphorus array for SERS immunoassay of SARS-CoV-2 spike protein

As a rapid, highly sensitive, and user-friendly technique, surface-enhanced Raman scattering (SERS) has an extraordinary appeal to home self-test of COVID-19 during the post pandemic era. However, most of the existing SERS substrates have been still criticized in stability, repeatability, and sample enrichment. To address these obstacles, a novel non-metallic SERS substrate with porous surfaces and array geometry was developed by in-situ growing ZIF-67 particles on two-dimensional violet phosphorus (VP) matrix. Chemical enhancement was prominently promoted by the synergistic photoinduced charge transfer resonance in the hybrid band structure of the ZIF-67@VP substrate, facilitating a noble metal-similar enhancement factor of 6.11 × 107. The biocompatible ZIF-67@VP porous array with attractive enhancement capability and high anchoring efficiency was further utilized to monitoring SARS-CoV-2 spike protein in practical saliva samples based on a sandwich immunostructure, achieving a limit of detection of 1.7 ng/mL assisted by black phosphorus nanosheets. This nonmetallic immunoassay strategy with exceptional sensitivity and specificity is predicted to extend the utilization of SERS obstacle in daily infectious disease screening.

Synchronous preparation and modification of LDH hollow polyhedra by polydopamine: Synthesis and application

Layered double hydroxides (LDH) have irreplaceable advantages in the field of polymer flame retardancy, but their thermal stability and compatibility with matrix still need to be improved. In this paper, the bottom-up method is adopted, and the phosphorus series flame retardant triphenyl phosphate (TPP) was first encapsulated inside ZIF-67. On this basis, ZIF-67 was etched to produce LDH while modified by polydopamine (PDA) concomitantly. An organic coated polydopamine hollow cage lamellar LDH microstructure loaded with TPP was constructed, and its structure-performance relationship was verified. When 2 wt% TPP@LDH@Co-PDA was added to the epoxy resin, the LOI value of the composite was increased to 29.4 %, the peak heat release was reduced by 43.1 %, and the smoke release was significantly reduced. The unique microstructure endows epoxy composites with good flame retardancy, improves mechanical properties, and provides a new solution to the migration problem of phosphorous based flame retardants.

Ni/Co/Carbon nitride derived from ZIF-67 (MOF) nanocomposite: Enhanced light-driven photocatalytic degradation of methylparaben, mechanism & toxicity

A nickel oxide/cobalt/carbon nitride (Ni/Co/CN) nanocomposite synthesized via co-precipitation was used for the degradation of methylparaben (MEP). Various analytical techniques were used to ascertain the structural, optical, and electrochemical characteristics of the synthesized nanocomposite. The unique nature of the compound without any free particles over the CN was established. Photocatalytic degradation studies demonstrated the superiority of 3-Ni/Co/CN over bare NiO, Co/CN, 1-Ni/Co/CN, and 5-Ni/Co/CN. Near complete MEP degradation (100%) was achieved after 120 min of incubation with MEP 75 mg L-1 in acidic medium pH (3) for an initial concentration of 3-Ni/Co/CN (10 mg/100 mL). HPLC-MS/MS analysis was used to elucidate the degradation pathway, and the catalyst was found stable for four subsequent cycles. Hence, our nanocatalyst effectively degraded MEP. Furthermore, microbial, aquatic, and animal studies demonstrated the environmental efficiency of the synthesized nanomaterials.

Glucose oxidase-like Co-MOF nanozyme-catalyzed self-powered sensor for sensitive detection of trace atrazine in complex environments

The self-powered sensor (SPS) is a sensor method that does not require the external power source and has the potential for portable detection of environmental contaminants. In this work, for the first time, a biomolecule-free SPS for detection of ultra-trace triazine endocrine disruptor atrazine (ATZ) with high sensitivity and selectivity is constructed using a glucose oxidase (GOD)-like cobalt metal-organic framework (Co-MOF) nanozyme-modified high-performance anode and a molecularly imprinted cathode. By modulating the size and morphology of the prepared materials, Co-MOF nanozyme with superior GOD-like property (Michaelis constant Km = 15.8 mM) has been obtained and modified at the anode to catalyze glucose oxidation with high efficiency and provide energy continuously and stably for the SPS. The separation mode of anodic energy supply-cathodic recognition ensures the recognition effect without affecting the catalytic characteristic of Co-MOF and the output signal of the SPS. The designed SPS has a wide linear range of 1 pM-100 nM and a detection limit as low as 0.65 pM, as well as superior selectivity and good stability. The present work provides a promising approach for the design of self-powered sensors which can be extended to detection of a wider range of environmental pollutants.

Graphene-grafted bimetallic MOF membranes for hazardous & toxic contaminants treatment

Development of membrane with improved carbon dioxide (CO2) gas separation capability is a significant challenge. However, the fabrication of membrane that efficiently separate and purification CO2-containing gases has been the focus of global attention. Cellulose Acetate (CA) has robust reinforcing characteristics when incorporated within a suitable polymer matrix. This work focus on the synthesis of novel mixed matrix membranes (MMMs) by introducing Graphene-grafted bimetallic MOFs in Cellulose Acetate polymer. The graphene-grafted bimetallic MOF (GG-BM MOFs) was prepared by a hydrothermal technique. Whereas, the solution casting approach used to fabricate membranes. The 1-5 wt% of GG-BM MOFs incorporated into the CA matrix. The mechanical, hydrophilicity and adsorption characteristics of fabricated MMMs were investigated. The crystallinity of MMM enhanced after the addition of GG-BM MOFs. In addition, the mechanical characteristics of MMMs were improved with the incorporation of GG-BM MOFs inside the polymer matrix. Maximum stress and strain was obtained for 2 wt% MMM (36.4 N/mm2 and 11% respectively). The CO2 adsorption performance was evaluated at 10 bar and 45 °C. The FTIR results represent insignificant bond shifting with the addition GG-BM MOFs at these conditions. The overall results showed that MMMs containing 2 wt% GG-BM MOFs have good adsorption properties for CO2 i.e 3.15 wt% of CO2. The MMMs have shown a decrease in the mechanical properties and CO2 adsorption at the higher GG-BM MOFs loading due to the presence of agglomeration which was confirmed through SEM. Thus, the addition of GG-BM MOFs in the CA matrix positively altered the physicochemical characteristics of the resulting MMMs, which could assist them in achieving remarkable CO2 adsorption at 2 wt%.

Improving the Pervaporation Performance of PDMS Membranes for Trichloroethylene by Incorporating Silane-Modified ZSM-5 Zeolite

The hydrophobic nature of inorganic zeolite particles plays a crucial role in the efficacy of mixed matrix membranes (MMMs) for the separation of trichloroethylene (TCE) through pervaporation. This study presents a novel approach to further augment the hydrophobicity of ZSM-5. The ZSM-5 zeolite molecular sieve was subjected to modification using three different silane coupling agents, namely, n-octyltriethoxysilane (OTES), γ-methacryloxypropyltrimethoxysilane (KH-570), and γ-aminopropyltriethoxysilane (KH-550). The water contact angles of the resulting OTES@ZSM-5, KH-570@ZSM-5, and KH-550@ZSM-5 particles exhibited significant increases from 97.2° to 112.8°, 109.1°, and 102.7°, respectively, thereby indicating a notable enhancement in hydrophobicity. Subsequently, mixed matrix membranes (MMMs) were fabricated by incorporating the aforementioned silane-modified ZSM-5 particles into polydimethylsiloxane (PDMS), leading to a considerable improvement in the adsorption selectivity of these membranes towards trichloroethylene (TCE). The findings indicate that the PDMS membrane with a 20 wt.% OTES@ZSM-5 particle loading exhibits superior pervaporation performance. When subjected to a temperature of 30 °C, flow rate of 100 mL/min, and vacuum of 30 Kpa, the separation factor and total flux of a 3 × 10-7 wt.% TCE solution reach 328 and 155 gm-2·h-1, respectively. In comparison to the unmodified ZSM-5/PDMS membrane, the separation factor demonstrates a 41% increase, while the TCE flux experiences a 6% increase. Consequently, this approach effectively enhances the pervaporation separation capabilities of the PDMS membrane for TCE.

Enhancing electrochemical properties of a two-dimensional zeolitic imidazole framework by incorporating a conductive polymer for dopamine detection

The zeolitic imidazole framework with a leaf-shaped morphology (ZIF-L) has a wide range of promising applications in gas storage, battery materials, catalytic reactions, and optoelectronic devices due to its planar leaf-like structure and large surface area. However, the low conductivity, weak catalytic activity, and poor stability in the water dielectric medium of ZIF-L limit its further practical application. To solve these problems, we added the conductive polymer heterocyclic poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to ZIF-L for the sensitive detection of dopamine (DA). The synthesized composite ZIF-L/PEDOT:PSS (ZIF-L/PEDOT) not only retained the surface morphology of ZIF-L but also exhibited excellent electrochemical properties. The higher electrical conductivity of ZIF-L/PEDOT than that of ZIF-L was due to the enhanced electron transfer at the interface between ZIF-L and PEDOT:PSS. As a result, we developed an electrochemical biosensor based on the ZIF-L/PEDOT composite, which has a limit of detection of 7 nM for DA and a wide linear range from 25 nM to 500 μM. Furthermore, the current drop was negligible after 28 days, proving that the biosensor has excellent stability. Based on the above-mentioned outstanding performance, the ZIF-L/PEDOT-based biosensor was successfully used to detect DA in human serum samples. These results demonstrated that ZIF-L/PEDOT is expected to play an essential role in disease detection.

Enhancing High-Temperature Energy Storage Performance of PEI-Based Dielectrics by Incorporating ZIF-67 with a Narrow Bandgap

Polymer dielectrics are crucial for use in electrostatic capacitors, owing to their high voltage resistance, high energy storage density, and ultrahigh reliability. Furthermore, high-temperature-resistant polymer dielectrics are applied in various emerging fields. Herein, poly(ether imide) (PEI)-based polymer dielectrics prepared by adding a low loading of dimethylimidazolium cobalt (ZIF-67) with a narrow bandgaps are investigated. The results show that the composites exhibit considerably increased Young's modulus, suppressed conductivity loss, and improved breakdown strength compared with pure PEI. Consequently, a stable energy storage performance is realized for ZIF-67/PEI composites. Particularly, at 150 °C, 1 wt % ZIF-67/PEI composite affords an excellent energy storage density of 4.59 J/cm3 with a discharge energy efficiency of 80.6%, exhibiting a considerable increase compared with the values obtained for PEI (2.58 J/cm3 with a discharge energy efficiency of 68.8%). The results of this study reveal a feasible pathway to design polymer dielectrics with the potential for use in capacitive applications in harsh environments.

Metal-Organic Framework/Polyvinyl Alcohol Composite Films for Multiple Applications Prepared by Different Methods

The incorporation of different functional fillers has been widely used to improve the properties of polymeric materials. The polyhydroxy structure of PVA with excellent film-forming ability can be easily combined with organic/inorganic multifunctional compounds, and such an interesting combining phenomenon can create a variety of functional materials in the field of materials science. The composite membrane material obtained by combining MOF material with high porosity, specific surface area, and adjustable structure with PVA, a non-toxic and low-cost polymer material with good solubility and biodegradability, can combine the processability of PVA with the excellent performance of porous filler MOFs, solving the problem that the poor machinability of MOFs and the difficulty of recycling limit the practical application of powdered MOFs and improving the physicochemical properties of PVA, maximizing the advantages of the material to develop a wider range of applications. Firstly, we systematically summarize the preparation of MOF/PVA composite membrane materials using solution casting, electrostatic spinning, and other different methods for such excellent properties, in addition to discussing in detail the various applications of MOF/PVA composite membranes in water treatment, sensing, air purification, separation, antibacterials, and so on. Finally, we conclude with a discussion of the difficulties that need to be overcome during the film formation process to affect the performance of the composite film and offer encouraging solutions.

In Situ Synthesis of Crystalline MoS2@ZIF-67 Nanocomposite for the Efficient Removal of Methyl Orange Dye from Aqueous Media

The zeolitic imidazolate framework-67 (ZIF-67) adsorbent and its composites are known to effectively remove organic dyes from aqueous environments. Here, we report a unique crystalline MoS2@ZIF-67 nanocomposite adsorbent for the efficient removal of methyl orange (MO) dye from an aqueous medium. In situ synthetic techniques were used to fabricate a well-crystalline MoS2@ZIF-67 nanocomposite, which was then discovered to be a superior adsorbent to its constituents. The successful synthesis of the nanocomposite was confirmed using XRD, EDX, FTIR, and SEM. The MoS2@ZIF-67 nanocomposite exhibited faster adsorption kinetics and higher dye removal efficiency compared with its constituents. The adsorption kinetic data matched well with the pseudo-second-order model, which signifies that the MO adsorption on the nanocomposite is a chemically driven process. The Langmuir model successfully illustrated the MO dye adsorption on the nanocomposite through comparing the real data with adsorption isotherm models. However, it appears that the Freundlich adsorption isotherm model was also in competition with the Langmuir model. According to the acquired thermodynamics parameters, the adsorption of MO on the MoS2@ZIF-67 nanocomposite surface was determined to be spontaneous and exothermic. The findings of this research open an avenue for using the MoS2@ZIF-67 nanocomposite to efficiently remove organic dyes from wastewater efflux.

Response surface methodology, and artificial neural network model for removal of textile dye Reactive Yellow 105 from wastewater using Zeolitic Imidazolate-67 modified by Fe3O4 nanoparticles

The applicability of Zeolitic Imidazolate-67, Modified by Fe3O4 Nanoparticles, was studied for removing textile dye Reactive yellow 105 from wastewater by adsorption method using response surface methodology (RSM). For the adsorption characterization of the adsorbent used in HE-4G dye adsorption, BET, FTIR, XRD, and SEM analyses were performed. The impacts of variables, including initial HE-4G dye concentration (X1), pH (X2), adsorbent dosage (X3), and sonication time (X4), the highest removal efficiency as 98%, 10 mg/L initial concentration, pH 6, 0.025 g adsorbent dosage, and 6.0 min time respectively. Adsorption equilibrium and kinetic data it, that data were for the Langmuir isotherm, pseudo-second-order kinetics, and maximum adsorption capacity (105.0 mg/g), respectively. Thermodynamic parameters indicated HE-4G dye adsorption is feasible, spontaneous and exothermic. Promising treatment capabilities of the ZIF-67-Fe3O4NPs have been during the comparative adsorption removal of HE-4G dye from DI water against spiked natural water samples and synthetic Na+, K+, Ca2+, and Mg2+ solutions. The observed outcome is the suitability of the artificial neural network model as a tool for mean square error, (MSEANN = 0.53, and R2 = 0.9926) for removing HE-4G dye. Results that ZIF-67-Fe3O4NPs, like being recyclable, and cost-efficient made it a promising absorbent for wastewater.

Ni-Co bimetallic decorated dodecahedral ZIF as an efficient catalyst for photoelectrochemical degradation of sulfamethoxazole coupled with hydrogen production

In this work, a NiCo bimetallic ZIF (BMZIF) dodecahedron material has been synthesized by the precipitation approach and then used for simultaneously photoelectrocatalytic degradation of sulfamethoxazole (SMX) and hydrogen production. The combination of Ni/Co loading in ZIF structure increased the specific surface area 1484 (m² g^-1) and photocurrent density (0.4 mA cm^-2), which can facilitate the good charge transfer efficiency. In presence of peroxymonosulfate (PMS, 0.1 mM), the complete degradation of SMX (10 mg L^-1) was achieved at initial pH of 7 within 24 min, with the pseudo-first-order rate constants of 0.18 min^-1 and TOC removal efficiency of 85 %. Radical scavenger experiments affirm that ^•OH radicals were the primary oxygen reactive species to drive the SMX degradation. Along with SMX degradation at the anode, the H₂ production was observed at the cathode (140 μmol cm^-2 h^-1), which was 1.5 and 3 times higher than that of Co-ZIF and Ni-ZIF, respectively. The superior catalytic performance of BMZIF was assigned to the distinctive internal structure and synergistic effect between ZIF and Ni/Co bimetals, which improves light absorption and charge conduction efficiency. This study may provide insight into the new way to treat polluted water and simultaneously produce green energy using bimetallic ZIF in a PEC system.

Asymmetric membranes for gas separation: interfacial insights and manufacturing

State-of-the-art gas separation membrane technologies combine the properties of polymers and other materials, such as metal-organic frameworks to yield mixed matrix membranes (MMM). Although, these membranes display an enhanced gas separation performance, when compared to pure polymer membranes; major challenges remain in their structure including, surface defects, uneven filler dispersion and incompatibility of constituting materials. Therefore, to avoid these structural issues posed by today's membrane manufacturing methodologies, we employed electrohydrodynamic emission and solution casting as a hybrid membrane manufacturing method, to produce ZIF-67/cellulose acetate asymmetric membranes with improved gas permeability and selectivity for CO2/N2, CO2/CH4, and O2/N2. Rigorous molecular simulations were used to reveal the key ZIF-67/cellulose acetate interfacial phenomena (e.g., higher density, chain rigidity, etc.) that must be considered when engineering optimum composite membranes. In particular, we demonstrated that the asymmetric configuration effectively leverages these interfacial features to generate membranes superior to MMM. These insights coupled with the proposed manufacturing technique can accelerate the deployment of membranes in sustainable processes such as carbon capture, hydrogen production, and natural gas upgrading.

Task-specific polymeric membranes to achieve high gas-liquid mass transfer

In the current study, Polyimide (P84)-based polymeric membranes were fabricated and used as spargers in the bubble column reactor (BCR) to get a high gas-liquid mass transfer (GL-MT) rate of oxygen in water. Different polymeric membranes were fabricated by incorporating polyvinyl pyrrolidone (PVP) as a porogen and a Zeolitic Imidazolate Framework (ZIF-8) to induce high porosity and hydrophobicity in the membranes. The GL-MT efficiency of membranes was evaluated by measuring the overall volumetric mass transfer coefficient (k_La) of oxygen in air. The k_La of O₂ (in air) was measured by supplying the gas through a fixed membrane surface area of 11.94 cm² at a fixed gas flow rate of 3L/min under atmospheric pressure. The results revealed that adding porogen and ZIF-8 increased the porosity of the membranes compared to the pure polymeric membranes. In comparison, the ZIF-8 (3 wt%) based membrane showed the highest porosity (80%), hydrophobicity (95° contact angle) and k_La of oxygen in air (241.2 h^-1) with 78% saturation in only 60 s. ZIF-8 based membranes showed the potential to increase the amount of dissolved oxygen in BCR by reducing the bubble size, increasing the number of bubbles, and improving the hydrophobicity. The study showed that ZIF-8 based membrane diffusers are expected to produce high GL-MT in microbial syngas fermentation. To the best of our knowledge, this is the first study on the fabrication and application of polymeric membranes for GL-MT applications. Further research should be conducted under real fermentation conditions to assess the practicality of the system to support substrate utilization, microbial growth, and product formation.

Cellulose acetate based sustainable nanostructured membranes for environmental remediation

Membrane-based gas separation has a great potential for reducing environmentally hazardous carbon dioxide (CO₂) gas. The polymeric membranes developed for CO₂ capturing have some limitations in their selectivity and permeability. There is a need to overcome these issues and developed such membranes having high-performance CO₂ capture with cost-effectiveness. The present study aimed to synthesize mixed matrix membranes (MMMs) having improved properties CO₂ adsorption performance and stability than that of pure polymer. Further, the effect on CO₂ adsorption by increasing the filler concentration in MMMs was investigated. The MMMs were synthesized by incorporating (1-5 wt%) Cu-MOF-GO composites as filler into cellulose-acetate (CA) polymer matrix by adopting the solution casting method. The performance of MMMs was studied by changing the Cu-MOF-GO composite concentration (1-5 wt%) in the polymer matrix at 45 °C up to 15 bar. Morphological analysis by using SEM confirms that by increasing the concentration of Cu-MOF-GO more than 3% will result in their agglomeration in MMM. The successful incorporation of MOF within the polymer matrix of MMMs was confirmed through the presence of functional groups using FTIR and Raman spectroscopy. XRD analysis revealed that pure CA changes its semi-crystalline behaviour into crystalline by the addition of Cu-MOF-GO. The maximum tensile stress and strain rate of MMMs was 45.1 N/mm² and 12.8%. In addition, with an increase in (4-5 wt%) Cu-MOF-GO concentration the hydrophilicity of MMMs decreases. The maximum uptake rate of CO₂ was 1.79 mmol/g and 7.98 wt% at 15 bar. The adsorption results conclude that Cu-MOF-GO composite and CA-based MMM can be effective for CO₂ capture.

Decorating MnO2 nanosheets on MOF-derived Co3O4 as a battery-type electrode for hybrid supercapacitors

Metal–organic framework-derived materials are now considered potential next-generation electrode materials for supercapacitors. In this present investigation, Co₃O₄@MnO₂ nanosheets are synthesized using ZIF-67, which is used as a sacrificial template through a facile hydrothermal method. The unique vertically grown nanosheets provide an effective pathway for rapidly transporting electrons and ions. As a result, the ZIF-67 derived Co₃O₄@MnO₂-3 electrode material shows a high specific capacitance of 768 C g⁻¹ at 1 A g⁻¹ current density with outstanding cycling stability (86% retention after 5000 cycles) and the porous structure of the material has a good BET surface area of 160.8 m² g⁻¹. As a hybrid supercapacitor, Co₃O₄@MnO₂-3//activated carbon exhibits a high specific capacitance (82.9 C g⁻¹) and long cycle life (85.5% retention after 5000 cycles). Moreover, a high energy density of 60.17 W h kg⁻¹ and power density of 2674.37 W kg⁻¹ has been achieved. This attractive performance reveals that Co₃O₄@MnO₂ nanosheets could find potential applications as an electrode material for high-performance hybrid supercapacitors.

Metal–organic framework-derived materials are now considered potential next-generation electrode materials for supercapacitors.

Exploring the potential of highly selective deep eutectic solvents (DES) based membranes for dehydration of butanol via pervaporation

N-butanol has unique physicochemical and combustion properties, similar to gasoline, which makes it an environmentally friendly alternative to conventional fuels. To improve the efficiency, the dehydration of butanol is necessary. This paper aims to investigate the performance of Deep Eutectic Solvents (DESs) based membranes for the dehydration of n-butanol by the pervaporation process. Three DES with different combinations of hydrogen bond donors and acceptors, i.e., DL-menthol: Lauric acid (DES), DL-menthol-Palmitic acid (DES), and [TETA] Cl: Thymol (DES), were used. We hypothesized that (i) incorporation of hydrophobic DES would increase the hydrophobicity of the membranes; (ii) specific functional groups (phenolic group, amine group) in DESs would enhance the butanol-philic character of membranes, and (iii) hydrophobic DESs would increase the butanol separation efficiency and permeability of membranes. FTIR analysis and physicochemical parameters of the resultant liquid mixture validated the DESs' production. The DESs were then filled into the permeable support, resulting in supported liquid membranes (SLMs). An additional layer of polydimethylsiloxane (PDMS) was coated directly on the DES-PSf layer to prevent leaching out of DES. A feed containing a 6 wt % aqueous solution of butanol under varying temperatures was studied. The results showed that among all membranes, [TETA] Cl: Thymol DES-based membrane showed the highest sorption of 36% at room temperature. The introduction of DES in membranes resulted in a remarkable increase in the separation factor while sustaining a reasonable flux. Among all the membranes, the DL-menthol: Lauric acid (DES) based membrane exhibited the highest separation factor of 57 with a total flux of 0.11 kg/m². h. Significantly high butanol-water separation was attributed to the low viscosity and high butanol solubility of the chosen DES, which makes it a suitable substitute to conventional ILs.

Non-enzymatic electrochemical sensing of dopamine from COVID-19 quarantine person

The worldwide outbreak of COVID-19 pandemic, is not only a great threat to the victim life but it is leaving invisible devastating negative affect on mental health of quarantined individual because of isolation, depression, bereavement, and loss of income. Therefore, the precise monitoring catecholamine neurotransmitters specifically of dopamine (DA) is of great importance to assess the mental health. Thus, herein we have synthesized Co-based zeolitic imidazolate framework (ZIF-67) through solvothermal method for precise monitoring of DA. To facilitate the fast transportation of ions, highly conductive polymer, poly(3,4-ethylenedioxythiophene; PEDOT) has been integrated on the surface of ZIF-67 which not only provides the smooth pathway for ions/electrons transportation but also saves the electrode from pulverization. The fabricated ZIF-67/PEDOT electrode shows a significant sensing performance towards DA detection in terms of short diffusion pathways by expositing more active sites, over good linear range (15-240 μM) and a low detection limit of (0.04 μM) even in the coexistence of the potentially interfering molecules. The developed ZIF-67/PEDOT sensor was successfully employed for sensitive and selective monitoring of DA from COVID-19 quarantined person blood, thus suggesting reliability of the developed electrode.

Dual-ZIF-derived "reassembling strategy" to hollow MnCoS nanospheres for aqueous asymmetric supercapacitors

Construction of delicate nanostructures with a facile, mild-condition and economical method is a key issue for building high-performance electrode materials. We demonstrate a facile and novel "reassembling strategy" to hollow MnCoS nanospheres derived from dual-ZIF for supercapacitors. The spherical shell's surface structure, thickness and Mn distribution were controlled by regulating the solvothermal reaction time. The chemical composition, phases, specific surface areas and microstructure were studied and the electrochemical performances were systematically estimated. As the unique low-crystalline and optimized hollow nanosphere structure contributes to increasing active sites, MnCoS nanospheres exhibit excellent electrochemical performance. The test results show that the specific capacitance increases with increasing solvothermal time, and the MCS with a 5 h reaction time exhibits optimal electrochemical properties with a high specific capacity of 957 C g-1 (1 A g-1). Furthermore, an MCS-5//AC asymmetric supercapacitor device delivers a specific energy as high as 36.9 W h kg-1 at a specific power of 750 W kg-1.

Electrospinning of ZIF-67 Derived Co-C-N Composite Efficiently Activating Peroxymonosulfate to Degrade Dimethyl Phthalate

In this work, an efficient cage-core peroxymonosulfate (PMS) catalyst was synthesized by applying an electrospinning–calcination process to the cobalt–zeolitic imidazole framework (ZIF-67) crystals for the catalytic degradation of dimethyl phthalate (DMP). The morphology and surface properties of the synthesized materials (ZIF-67, Z600 and ZP400/600/800) were well characterized. ZP600 showed great performance for the catalytic degradation of DMP in the initial pH range of 7.5–10.5. The removal rate of DMP could reach 90.4% in 60 min under optimum dosages of reagents (catalyst = 0.1 g/L, PMS = 0.5 mM, DMP = 6 ppm), and the mineralization degree of contaminant could reach 65%. By quenching experiments, it was determined that sulfate radical (SO4−·) and hydroxyl radical (·OH) dominated the degradation process. Moreover, due to the good magnetism, ZP600 could be easily separated from liquid and showed great reusability in five-cycle reaction experiments. Surprisingly, with the cover of cage-like polyacrylonitrile (PAN) fibers, the cobalt leaching amount of ZP600 decreased by about 87%. This study would expand the application of the electrospinning process in the development of functional materials for water purification.

Bimetallic CoCu-ZIF material for efficient visible light photocatalytic fuel denitrification

Effective design of photocatalysts is an effective method to improve the separation of photogenerated carriers, which improves the photocatalytic performance of photocatalysts. In this work, CoCu-ZIF materials with bimetallic structure were synthesized at room temperature for efficient photocatalytic fuel denitrification. The properties and structures of CoCu-ZIF photocatalysts can be effectively controlled by adjusting the molar ratio of cobalt to copper. The as-prepared CoCu-ZIF photocatalysts were characterized by XRD, FT-IR, SEM, TEM, UV-vis, Raman, BET and other techniques. The photoactivity of CoCu-ZIF for the denitrogenation of NCCs has been evaluated using visible light (λ ≥ 420 nm). The results indicate that Co₈Cu₂-ZIF photocatalysts exhibit excellent photocatalytic properties, in which the denitrification rate almost reached 80% after 4 hours under visible light irradiation, which is higher than the degradation ability of ZIF-67 (38%). Transient photoelectrochemical experiments and EIS Nyquist plots indicate that Co₈Cu₂-ZIF with unique structure efficiently improves the separation and transfer of photogenerated electron-hole pairs. Moreover, a possible reaction mechanism was proposed by LC-MS analysis.

Directionally In Situ Self-Assembled, High-Density, Macropore-Oriented, CoP-Impregnated, 3D Hierarchical Porous Carbon Sheet Nanostructure for Superior Electrocatalysis in the Hydrogen Evolution Reaction

3D ZIF-67-particles-impregnated cellulose-nanofiber nanosheets with oriented macropores are synthesized via directional-freezing-assisted in situ self-assembly, and converted to 3D CoP-nanoparticle (NP)-embedded hierarchical, but macropores-oriented, N-doped carbon nanosheets via calcination and phosphidation. The obtained nanoarchitecture delivers overpotentials at 10 and 50 mA cm^-2 and Tafel slope of 82.1 and 113.4 mV and 40.8 mV dec^-1 in 0.5 M H₂ SO₄ , and of 97.1 and 136.6 mV and 51.2 mV dec^-1 in 1 M KOH, all of which are superior to those of the most reported non-noble-metal-based hydrogen evolution reaction (HER) catalysts. This catalyst even surpasses commercial Pt/C for a much lower overpotential at high current densities, which is essential for large-scale hydrogen production. Its catalytic activity can be further optimized to become one of the best in both 0.5 M H₂ SO₄ and 1 M KOH. The outstanding catalytic activity is ascribed to the uniformly-dispersed small CoP NPs in the 3D carbon sheets and the hierarchical nanostructure with rich oriented pores. This work develops a facile, economical, and universal self-assembly strategy to fabricate uniquely nanostructured hybrids to simultaneously promote charge transfer and mass transport, and also offers an inexpensive and high-performance HER catalyst toward industry-scale water splitting.

Tailoring unique neural-network-type carbon nanofibers inserted in CoP/NC polyhedra for robust hydrogen evolution reaction

Three-dimensional catalysts have attracted great attention in the field of the hydrogen evolution reaction (HER).However, great challenges remain in structural innovation and performance enhancement. Herein we designed and tailored a unique three-dimensional cross-linked neural network-like CoP-based composite, that is, carbon nanofibers inserted in CoP/NC polyhedra derived from in situ self-assembled bacterial cellulose (BC) wired ZIF-67 polyhedra via high-temperature carbonization and subsequent phosphorization. The obtained integrated catalyst (3-D CNF@CoP/NC) consists of CoP/NC polyhedra with abundant active sites as the "neurons" and carbon nanofibers as the "axons", and displayed remarkable activity with an overpotential of 64.5 mV and 105.6 mV at 10 mA cm^-2 in 0.5 M H₂SO₄ and 1 M KOH respectively and good stability with negligible current change after 80 h of chronoamperometric measurement or 4000 CV cycles. This work offers a high-performance HER catalyst and paves a new way for the rational engineering of unique 3-D interconnected hierarchical porous networks featuring ultrafast charge transfer and mass transport.

Metal Organic Frameworks Derived Sustainable Polyvinyl Alcohol/Starch Nanocomposite Films as Robust Materials for Packaging Applications

Bio-nanocomposites-based packaging materials have gained significance due to their prospective application in rising areas of packaged food. This research aims to fabricate biodegradable packaging films based upon polyvinyl alcohol (PVA) and starch integrated with metal-organic frameworks (MOFs) or organic additives. MOFs offer unique features in terms of surface area, mechanical strength, and chemical stability, which make them favourable for supporting materials used in fabricating polymer-based packaging materials. zeolitic imidazolate frameworks (ZIFs) are one of the potential candidates for this application due to their highly conductive network with a large surface area and high porosity. Present research illustrates a model system based on ZIF-67 (C₈H₁₀N₄Co) bearing 2–10 wt.% loading in a matrix of PVA/starch blend with or without pyrolysis to probe the function of intermolecular interaction in molecular packing, tensile properties, and glass transition process. ZIF-67 nanoparticles were doped in a PVA/starch mixture, and films were fabricated using the solution casting method. It was discovered through scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) that addition of ZIF-67 and pyrolyzed ZIF-67 changed and enhanced the thermal stability of the membrane. Moreover, 2–10 wt.% loading of ZIF-67 effected the thermal stability, owing to an interlayer aggregation of ZIF-67. The membranes containing pyrolyzed ZIF-67 showed mechanical strength in the order of 25 MPa in a moderate loading of pyrolyzed ZIF-67 (i.e., at 4 wt.%). The crystallinity enhanced by an increment in ZIF-67 loading. On the other hand, pyrolyzed ZIF-67 carbon became amorphous because of the inert environment and elevated temperature. The surface area also increased after the pyrolysis, which helped to increase the strength of the composite films.

A Review on Mixed Matrix Membranes for Solvent Dehydration and Recovery Process

Solvent separation and dehydration are important operations for industries and laboratories. Processes such as distillation and extraction are not always effective and are energy-consuming. An alternate approach is offered by pervaporation, based on the solution-diffusion transport mechanism. Polymer-based membranes such as those made of Polydimethylsiloxane (PDMS) have offered good pervaporation performance. Attempts have been made to improve their performance by incorporating inorganic fillers into the PDMS matrix, in which metal-organic frameworks (MOFs) have proven to be the most efficient. Among the MOFs, Zeolitic imidazolate framework (ZIF) based membranes have shown an excellent performance, with high values for flux and separation factors. Various studies have been conducted, employing ZIF-PDMS membranes for pervaporation separation of mixtures such as aqueous-alcoholic solutions. This paper presents an extensive review of the pervaporation performance of ZIF-based mixed matrix membranes (MMMs), novel synthesis methods, filler modifications, factors affecting membrane performance as well as studies based on polymers other than PDMS for the membrane matrix. Some suggestions for future studies have also been provided, such as the use of biopolymers and self-healing membranes.

Novel Pervaporation Membranes Based on Biopolymer Sodium Alginate Modified by FeBTC for Isopropanol Dehydration

Modern society strives for the development of sustainable processes that are aimed at meeting human needs while preserving the environment. Membrane technologies satisfy all the principles of sustainability due to their advantages, such as cost-effectiveness, environmental friendliness, absence of additional reagents and ease of use compared to traditional separation methods. In the present work, novel green membranes based on sodium alginate (SA) modified by a FeBTC metal–organic framework were developed for isopropanol dehydration using a membrane process, pervaporation. Two kinds of SA-FeBTC membranes were developed: (1) untreated membranes and (2) cross-linked membranes with citric acid or phosphoric acid. The structural and physicochemical properties of the developed SA-FeBTC membranes were studied by spectroscopic techniques (FTIR and NMR), microscopic methods (SEM and AFM), thermogravimetric analysis and swelling experiments. The transport properties of developed SA-FeBTC membranes were studied in the pervaporation of water–isopropanol mixtures. Based on membrane transport properties, 15 wt % FeBTC was demonstrated to be the optimal content of the modifier in the SA matrix for the membrane performance. A membrane based on SA modified by 15 wt % FeBTC and cross-linked with citric acid possessed optimal transport properties for the pervaporation of the water–isopropanol mixture (12–100 wt % water): 174–1584 g/(m2 h) permeation flux and 99.99 wt % water content in the permeate.