Fluorinated Nanosized Zeolitic-Imidazolate Frameworks as Potential Devices for Mechanical Energy Storage.

Fluorination is one of the most efficient and universal strategies to increase the hydrophobicity of materials and consequently their water stability. Zeolitic-imidazolate frameworks (ZIFs), which have limited stability in aqueous media and even lower stability when synthesized on a nanometric scale, can greatly benefit from the incorporation of fluorine atoms, not only to improve their stability but also to provide additional properties. Herein, we report the preparation of two different fluorinated ZIFs through a simple and scalable approach by using mixed ligands [2-methylimidazole, as a common ligand, and 4-(4-fluorophenyl)-1-imidazole ( linker) or 2-methyl-5-(trifluoromethyl)-1-imidazole ( linker) as a dopant], demonstrating the high versatility of the synthetic method developed to incorporate different fluorine-containing imidazole-based ligands.

Highly Dispersed Pd@ZIF-8 for Photo-Assisted Cross-Couplings and CO to Methanol: Activity and Selectivity Insights.

Our study unveils a pioneering methodology that effectively distributes Pd species within a zeolitic imidazolate framework-8 (ZIF-8). We demonstrate that Pd can be encapsulated within ZIF-8 as atomically dispersed Pd species that function as an excited-state transition metal catalyst for promoting carbon-carbon (C-C) cross-couplings at room temperature using visible light as the driving force. Furthermore, the same material can be reduced at 250 °C, forming Pd metal nanoparticles encapsulated in ZIF-8.

A robust Fe-based heterogeneous photocatalyst for the visible-light-mediated selective reduction of an impure CO stream.

The transformation of CO into value-added products from an impure CO stream, such as flue gas or exhaust gas, directly contributes to the principle of carbon capture and utilization (CCU). Thus, we have developed a robust iron-based heterogeneous photocatalyst that can convert the exhaust gas from the car into CO with an exceptional production rate of 145 μmol g h. We characterized this photocatalyst by PXRD, XPS, ssNMR, EXAFS, XANES, HR-TEM, and further provided mechanistic experiments, and multi-scale/level computational studies.

On the Low-Pressure Hysteresis (LPH) in Gas Sorption Isotherms of Porous Carbons.

This study investigates the origin of low-pressure hysteresis (LPH) in the adsorption and desorption of three different probe molecules: carbon dioxide, nitrogen, and argon, across various adsorption temperatures (from cryogenic to room temperature), and within five different carbon materials: synthetic carbons (pristine and one post-synthetically oxidized) and natural coal. Significant attention is dedicated to elucidating LPH in oxidized samples outgassed at various temperatures (120-350 °C). Experimental results show that insufficient outgassing temperature can lead to unreliable data due to artificial LPH and significantly underestimated textural properties, primarily caused by porosity blockage from substances like moisture.

Exceptional performance of Fe@carbon-rich nanoparticles prepared via hydrothermal carbonization of oil mill wastes for HS removal.

Carbon-encapsulated iron oxide nanoparticles (CE-nFe) have been obtained from an industrial waste (oil mill wastewater-OMW, as a carbonaceous source), and using iron sulfate as metallic precursor. In an initial step, the hydrochar obtained has been thermally activated under an inert atmosphere at three different temperatures (600 °C, 800 °C and 1000 °C). The thermal treatment promotes the development of core-shell nanoparticles, with an inner core of α-Fe/FeO, surrounded by a well-defined graphite shell.

Improved photocatalytic performance of TiO/carbon photocatalysts: Role of carbon additive.

A series of TiO - based photocatalysts have been prepared by the incorporation of 10 wt% of various carbon-based nanomaterials as modifying agents to titania. More specifically, commercial TiO P25 was modified through a wet impregnation approach with methanol with four different carbon nanostructures: single-walled carbon nanotubes (SWCNTs), partially reduced graphene oxide (prGO), graphite (GI), and graphitic carbon nitride (gCN). Characterization results (XPS and Raman) anticipate the occurrence of important interfacial phenomena, preferentially for samples TiO/SWCNT and TiO/prGO, with a binding energy displacement in the Ti 2p contribution of 1.

Copper nanoparticles encapsulated in zeolitic imidazolate framework-8 as a stable and selective CO hydrogenation catalyst.

Metal-organic frameworks have drawn attention as potential catalysts owing to their unique tunable surface chemistry and accessibility. However, their application in thermal catalysis has been limited because of their instability under harsh temperatures and pressures, such as the hydrogenation of CO to methanol. Herein, we use a controlled two-step method to synthesize finely dispersed Cu on a zeolitic imidazolate framework-8 (ZIF-8).

Advanced Removal of Dyes with Tuning Carbon/TiO Composite Properties.

This study evaluates the removal of several dyes with different charge properties, i.e., anionic (Acid Red 88), cationic (Basic Red 13), and neutral (Basic Red 5) using transition metal-doped TiO supported on a high-surface-area activated carbon.

Design of Full-Temperature-Range RWGS Catalysts: Impact of Alkali Promoters on Ni/CeO.

Reverse water gas shift (RWGS) competes with methanation as a direct pathway in the CO recycling route, with methanation being a dominant process in the low-temperature window and RWGS at higher temperatures. This work showcases the design of multi-component catalysts for a full-temperature-range RWGS behavior by suppressing the methanation reaction at low temperatures. The addition of alkali promoters (Na, K, and Cs) to the reference Ni/CeO catalyst allows identifying a clear trend in RWGS activation promotion in both low- and high-temperature ranges.

Post-Synthetic Surface Modification of Metal-Organic Frameworks and Their Potential Applications.

Metal-organic frameworks (MOFs) are porous hybrid materials with countless potential applications. Most of these rely on their porous structure, tunable composition, and the possibility of incorporating and expanding their functions. Although functionalization of the inner surface of MOF crystals has received considerable attention in recent years, methods to functionalize selectively the outer crystal surface of MOFs are developed to a lesser extent, despite their importance.

Controlling the Adsorption and Release of Ocular Drugs in Metal-Organic Frameworks: Effect of Polar Functional Groups.

A series of UiO-66 materials with different functional groups (-H, -NH, and -NO) have been evaluated for the adsorption and release of a common ocular drug such as brimonidine tartrate. UiO-66 samples were synthesized under solvothermal conditions and activated by solvent exchange with ethanol. Experimental results suggest that the incorporation of surface functionalities gives rise to the development of structural defects (missing linker defects) but without altering the basic topology of the UiO-66 framework.

Rapid and efficient hydrogen clathrate hydrate formation in confined nanospace.

Clathrate hydrates are crystalline solids characterized by their ability to accommodate large quantities of guest molecules. Although CH and CO are the traditional guests found in natural systems, incorporating smaller molecules (e.g.

Hierarchical Assembly of a Micro- and Macroporous Hydrogen-Bonded Organic Framework with Tailored Single-Crystal Size.

Porous organic molecular materials represent an emergent field of research in Chemistry and Materials Science due to their unique combination of properties. To enhance their performance and expand the number of applications, the incorporation of hierarchical porosity is required, as exclusive microporosity entails several limitations. However, the integration of macropores in porous organic molecular materials is still an outstanding challenge.

Effect of the Carbon Support and Conditions on the Carbothermal Synthesis of Cu-Molybdenum Carbide and Its Application on CO Hydrogenation to Methanol.

The synthesis of methanol by carbon dioxide hydrogenation has been studied using copper-molybdenum carbides supported on high surface area graphite, reduced graphene oxide and carbon nanotubes. The synthesis conditions and the effect of the support were studied. The catalysts were prepared in situ using H or He at 600 °C or 700 °C.

New Generation of MOF-Monoliths Based on Metal Foams.

Herein, it has been developed a method to prepare metallic foams starting from Zamak5 (ZnAlCu alloy) with different pore sizes. The Zamak5 metallic foam is designed to serve as a support and metallic precursor of ZIF-8. In this way, composite materials MOF-metal can be prepared, these composites have a large number of application in energy exchange processe such as: adsorption or chemical reactions.

Molybdenum Oxide Supported on TiAlC is an Active Reverse Water-Gas Shift Catalyst.

MAX phases are layered ternary carbides or nitrides that are attractive for catalysis applications due to their unusual set of properties. They show high thermal stability like ceramics, but they are also tough, ductile, and good conductors of heat and electricity like metals. Here, we study the potential of the TiAlC MAX phase as a support for molybdenum oxide for the reverse water-gas shift (RWGS) reaction, comparing this new catalyst to more traditional materials.

Chlorination of a Zeolitic-Imidazolate Framework Tunes Packing and van der Waals Interaction of Carbon Dioxide for Optimized Adsorptive Separation.

Molecular separation of carbon dioxide (CO) and methane (CH) is of growing interest for biogas upgrading, carbon capture and utilization, methane synthesis and for purification of natural gas. Here, we report a new zeolitic-imidazolate framework (ZIF), coined COK-17, with exceptionally high affinity for the adsorption of CO by London dispersion forces, mediated by chlorine substituents of the imidazolate linkers. COK-17 is a new type of flexible zeolitic-imidazolate framework Zn(4,5-dichloroimidazolate) with the SOD framework topology.

Surface Interactions and Mechanisms Study on the Removal of Iodide from Water by Use of Natural Zeolite-Based Silver Nanocomposites.

In this work a natural zeolite was modified with silver following two different methods to derive AgO and Ag nanocomposites. The materials were fully characterized and the results showed that both materials were decorated with nanoparticles of size of 5-25 nm. The natural and modified zeolites were used for the removal of iodide from aqueous solutions of initial concentration of 30-1400 ppm.

Design of a Functionalized Metal-Organic Framework System for Enhanced Targeted Delivery to Mitochondria.

Mitochondria play a key role in oncogenesis and constitute one of the most important targets for cancer treatments. Although the most effective way to deliver drugs to mitochondria is by covalently linking them to a lipophilic cation, the delivery of free drugs still constitutes a critical bottleneck. Herein, we report the design of a mitochondria-targeted metal-organic framework (MOF) that greatly increases the efficacy of a model cancer drug, reducing the required dose to less than 1% compared to the free drug and ca.

Magnetic dispersive solid-phase extraction using a zeolite-based composite for direct electrochemical determination of lead(II) in urine using screen-printed electrodes.

Magnetic dispersive solid-phase extraction (MDSPE) is combined with electrochemical detection by using a screen-printed carbon electrode modified with gold nanoparticles to determine lead(II). A zeolite-based magnetic composite was used as sorbent during sample preparation, thus combining the unique properties of zeolites as sorbent materials with the remarkable advantages provided by magnetic materials. Three different zeolite-based magnetic composites were initially investigated and characterized.

Carbon-GO Composites with Preferential Water versus Ethanol Uptake.

The elimination of small amounts of water from alcohols is by no means a trivial issue in many practical applications like, for instance, the dehumidification of biocombustibles. The use of carbonaceous materials as sorbents has been far less explored than that of other materials because their hydrophobic character has typically limited their water uptake. Herein, we designed a synthetic process based on the use of eutectic mixtures that allowed the homogeneous dispersion of graphene oxide (GO) in the liquid containing the carbon precursor, e.

Tuning porosity in macroscopic monolithic metal-organic frameworks for exceptional natural gas storage.

Widespread access to greener energy is required in order to mitigate the effects of climate change. A significant barrier to cleaner natural gas usage lies in the safety/efficiency limitations of storage technology. Despite highly porous metal-organic frameworks (MOFs) demonstrating record-breaking gas-storage capacities, their conventionally powdered morphology renders them non-viable.

A sol-gel monolithic metal-organic framework with enhanced methane uptake.

A critical bottleneck for the use of natural gas as a transportation fuel has been the development of materials capable of storing it in a sufficiently compact form at ambient temperature. Here we report the synthesis of a porous monolithic metal-organic framework (MOF), which after successful packing and densification reaches 259 cm (STP) cm capacity. This is the highest value reported to date for conformed shape porous solids, and represents a greater than 50% improvement over any previously reported experimental value.

Paving the way for methane hydrate formation on metal-organic frameworks (MOFs).

The presence of a highly tunable porous structure and surface chemistry makes metal-organic framework (MOF) materials excellent candidates for artificial methane hydrate formation under mild temperature and pressure conditions (2 °C and 3-5 MPa). Experimental results using MOFs with a different pore structure and chemical nature (MIL-100 (Fe) and ZIF-8) clearly show that the water-framework interactions play a crucial role in defining the extent and nature of the gas hydrates formed. Whereas the hydrophobic MOF promotes methane hydrate formation with a high yield, the hydrophilic one does not.