Ionic Liquids-Functionalized Zeolitic Imidazolate Framework for Carbon Dioxide Adsorption

Antibacterial collagen-guar gum hydrogels with zeolitic imidazolate framework-67 (ZIF-67): an innovative platform for advanced wound healing

The current challenge in developing wound healing dressings lies in achieving antibacterial effects while avoiding cytotoxicity to cells that are crucial for the healing process. Addressing this challenge, Zeolitic Imidazolate Framework-67 (ZIF-67), a cobalt-containing metal-organic framework (MOF), has emerged as a promising additive due to cobalt's broad-spectrum antimicrobial effects. This study developed semi-interpenetrating polymer network (semi-IPN) hydrogels by incorporating 1-3 wt.% ZIF-67 into collagen-guar gum matrices, resulting in biocomposites with tunable structural and functional properties. These biocomposites exhibit a fibrillar-granular morphology, uniform cobalt ion distribution on a semi-crystalline surface, and strong antibacterial activity against Escherichia coli (E. coli). At 3 wt.%, ZIF-67 accelerates gelation, strengthens crosslinking interactions, and enhances the storage modulus, thermal stability, and hydrolytic resistance of the hydrogels. Furthermore, biocomposites with 1 wt.% ZIF-67 also function as in-situ curcumin delivery systems, offering controlled release under physiological conditions and significant biodegradation in the presence of collagenase. In vitro tests demonstrate that the chemical composition of these hydrogels, regardless of ZIF-67 content, effectively supports monocyte and fibroblast metabolic activity, promotes cell proliferation, and increases interleukin-10 (IL-10) secretion by human monocytes. Additionally, the absence of hemolytic effects in human blood further underscores the safety and suitability of these hydrogel biocomposites for advanced wound treatment applications.

An Efficient Bifunctional Core-Shell ZIF-90@ZIF-67 Composite as a Stable Pickering Interfacial Catalyst for the Deacetalization-Knoevenagel Tandem Reaction

Exploiting advanced solid particles is crucial to the construction of Pickering emulsions catalysis. Recently, metal-organic frameworks (MOFs) have been used as ideal emulsifiers stabilizing Pickering emulsions for interfacial catalysis. Although Pickering emulsions stabilized by core-shell MOFs have significant importance in practical studies, to date there have been very limited reports on this topic. Herein, ZIF-90@ZIF-67, a core-shell material with simultaneous acid-base bifunctionality, was synthesized by seeded epitaxial growth. It was firstly applied as an emulsifier in Pickering emulsions to catalyze the deacetalization-Knoevenagel tandem reaction, which exhibited excellent catalytic properties and achieved extremely high yields. Additionally, ZIF-90@ZIF-67 showed high stability and remained well repeatable after five cycles. This work provides a platform for the design of structurally and functionally diverse MOF-based Pickering emulsions interfacial catalysis.

Different FeS Concentrations for Encapsulating ZIF-67 Nanomaterials toward the Enhanced Oxidation Evolution Reaction

Due to the slow kinetic nature of the oxygen evolution reaction (OER), the development of electrocatalysts with high efficiency, stability, and economy for oxygen production using metal-organic framework (MOF) materials is still a challenging research topic. In this work, we chose the different concentrations of FeS adsorption to encapsulate metal cobalt-based ZIF-67 MOF for preparing a series of electrocatalysts (ZIF1FeSx, x = 0.2, 0.5, 0.75, and 1), which were mainly explored for the electrocatalytic OER. Among them, ZIF1FeS0.5 has excellent electrocatalytic activity for OER, which can be driven by low overpotentials of 276 and 349 mV at 10 and 50 mA cm-2 current densities, and more than 92% of the initial overpotential can be maintained after 100 h of continuous OER at 10 mA cm-2 current density. This is mainly due to the electronic interactions between the cobalt-based MOF and the FeS, which shift the electronic state of the active metal center to a higher valence state for increasing the number of active sites and enhancing the efficiency of electron transfer to facilitate the OER course. This work may contribute to the design of effective catalysts for the OER during the electrolysis of alkaline solutions.

Reactive capture and electrochemical conversion of CO2 with ionic liquids and deep eutectic solvents

Ionic liquids (ILs) and deep eutectic solvents (DESs) have tremendous potential for reactive capture and conversion (RCC) of CO2 due to their wide electrochemical stability window, low volatility, and high CO2 solubility. There is environmental and economic interest in the direct utilization of the captured CO2 using electrified and modular processes that forgo the thermal- or pressure-swing regeneration steps to concentrate CO2, eliminating the need to compress, transport, or store the gas. The conventional electrochemical conversion of CO2 with aqueous electrolytes presents limited CO2 solubility and high energy requirement to achieve industrially relevant products. Additionally, aqueous systems have competitive hydrogen evolution. In the past decade, there has been significant progress toward the design of ILs and DESs, and their composites to separate CO2 from dilute streams. In parallel, but not necessarily in synergy, there have been studies focused on a few select ILs and DESs for electrochemical reduction of CO2, often diluting them with aqueous or non-aqueous solvents. The resulting electrode-electrolyte interfaces present a complex speciation for RCC. In this review, we describe how the ILs and DESs are tuned for RCC and specifically address the CO2 chemisorption and electroreduction mechanisms. Critical bulk and interfacial properties of ILs and DESs are discussed in the context of RCC, and the potential of these electrolytes are presented through a techno-economic evaluation.

Enhancing Hydrogen Sulfide Detection at Room Temperature Using ZIF-67-Chitosan Membrane

Developing new materials for energy and environment-related applications is a critical research field. In this context, organic and metal-organic framework (MOF) materials are a promising solution for sensing hazardous gases and saving energy. Herein, a flexible membrane of the zeolitic imidazole framework (ZIF-67) mixed with a conductivity-controlled chitosan polymer was fabricated for detecting hydrogen sulfide (H₂S) gas at room temperature (RT). The developed sensing device remarkably enhances the detection signal of 15 ppm of H₂S gas at RT (23 °C). The response recorded is significantly higher than previously reported values. The optimization of the membrane doping percentage achieved exemplary results with respect to long-term stability, repeatability, and selectivity of the target gas among an array of several gases. The fabricated gas sensor has a fast response and a recovery time of 39 s and 142 s, respectively, for 15 ppm of H₂S gas at RT. While the developed sensing device operates at RT and uses low bias voltage (0.5 V), the requirement for an additional heating element has been eliminated and the necessity for external energy is minimized. These novel features of the developed sensing device could be utilized for the real-time detection of harmful gases for a healthy and clean environment.

Construction of a Tl(I) voltammetric sensor based on ZIF-67 nanocrystals: optimization of operational conditions via response surface design

An electroanalytical sensor was constructed constituted on a carbon paste electrode (CPE) with a ZIF-67 modifier and devoted to the quantification of Tl(I). Several characterization tests including XRD, BET, FT-IR, SEM/EDS/mapping, TEM, impedance spectroscopy (EIS), and cyclic voltammetry (CV) were performed on the synthesized ZIF-67 nanocrystals and CPE matrix. Central composite design (CCD) was used to assess the impact of variables affecting the sensor response, including the weight percent of ZIF-67 (14%), the pH of the thallium accumulation solution (6.4), and accumulation time (315 s) as well as the accumulation potential (-1.2 V). The direct linear relationship between the sensor response and the concentration of Tl(I) is in the interval of 1.0×10^-10 to 5.0×10^-7 M (coefficient of determination = 0.9994). The detection limit is approximately 1.0 × 10^-11 M. The right selection of the MOF makes this sensor highly resistant to the interference of other ions. High selectivity against common interferences in the measurement of thallium (such as Pb(II) and Cd(II)) is an important feature of this sensor. To confirm the performance of the prepared sensor, the amount of thallium in the real sample was determined.

Enhanced Desalination Performance of Capacitive Deionization Using Nanoporous Carbon Derived from ZIF-67 Metal Organic Frameworks and CNTs

Capacitive deionization (CDI) based on ion electrosorption has recently emerged as a promising desalination technology due to its low energy consumption and environmental friendliness compared to conventional purification technologies. Carbon-based materials, including activated carbon (AC), carbon aerogel, carbon cloth, and carbon fiber, have been mostly used in CDI electrodes due their high surface area, electrochemical stability, and abundance. However, the low electrical conductivity and non-regular pore shape and size distribution of carbon-based electrodes limits the maximization of the salt removal performance of a CDI desalination system using such electrodes. Metal-organic frameworks (MOFs) are novel porous materials with periodic three-dimensional structures consisting of metal center and organic ligands. MOFs have received substantial attention due to their high surface area, adjustable pore size, periodical unsaturated pores of metal center, and high thermal and chemical stabilities. In this study, we have synthesized ZIF-67 using CNTs as a substrate to fully utilize the unique advantages of both MOF and nanocarbon materials. Such synthesis of ZIF-67 carbon nanostructures was confirmed by TEM, SEM, and XRD. The results showed that the 3D-connected ZIF-67 nanostructures bridging by CNTs were successfully prepared. We applied this nanostructured ZIF-67@CNT to CDI electrodes for desalination. We found that the salt removal performance was significantly enhanced by 88% for 30% ZIF-67@CNTs-included electrodes as compared with pristine AC electrodes. This increase in salt removal behavior was analyzed by electrochemical analysis such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements, and the results indicate reduced electrical impedance and enhanced electrode capacitance in the presence of ZIF-67@CNTs.

Poly(ionic liquid)-Modified Metal Organic Framework for Carbon Dioxide Adsorption

The design and synthesis of solid sorbents for effective carbon dioxide adsorption are essential for practical applications regarding carbon emissions. Herein, we report the synthesis of composite materials consisting of amine-functionalized imidazolium-type poly(ionic liquid) (PIL) and metal organic frameworks (MOFs) through complexation of amino groups and metal ions. The carbon dioxide adsorption behavior of the synthesized composite materials was evaluated using the temperature-programmed desorption (TPD) technique. Benefiting from the large surface area of metal organic frameworks and high carbon dioxide diffusivity in ionic liquid moieties, the carbon dioxide adsorption capacity of the synthesized composite material reached 19.5 cm3·g-1, which is much higher than that of pristine metal organic frameworks (3.1 cm3·g-1) under carbon dioxide partial pressure of 0.2 bar at 25 °C. The results demonstrate that the combination of functionalized poly(ionic liquid) with metal organic frameworks can be a promising solid sorbent for carbon dioxide adsorption.