Metal Organic Framework HKUST-1 Research Articles

Plasticity of Metal-Organic Framework Crystals: Thermally Activated Collapse of Nanopores.

Unrecoverable deformation or plasticity can be generated in crystalline metal-organic frameworks (MOFs) by compressive loading with different rates in various applications. Herein, plastic behaviors of MOF HKUST-1 crystals are investigated by a series of in situ strain-rate-dependent compression tests. The yield strength is found to significantly increase with increasing strain rate, following a logarithmic dependence. Our reactive molecular dynamics simulations illustrate that the yielding of crystalline HKUST-1 is induced by the irreversible collapse of its nanopores, which can be accelerated by thermal activation at finite temperatures. Based on this mechanism together with the reaction rate theory, we derive an analytical expression relating the yield strength of MOFs and strain rate, which fits experimental findings well. Overall, this work can expand our current understanding of MOF plasticity, which is of importance for the mechanical shaping and various applications of MOF crystals.

Insights about the effect of metal–organic framework hybridization with graphene-like materials

Abstract Hybrids based on the copper-based metal–organic framework HKUST-1 and graphene-like materials (GL) have been synthesized at different concentrations of GL, and investigated by means of solid state nuclear magnetic resonance (ssNMR) and x-ray absorption techniques (NEXAFS and XANES) with the aim of elucidating the effect of the hybridization on the structural properties of HKUST-1. The comparative analysis of ssNMR and x-ray absorption spectra recorded on parent materials (GL and pure HKUST-1) and on the hybrids indicates that the overall structural features of HKUST-1 are preserved in the presence of increasing GL amounts (up to 30 wt.%) and confirms that the framework development is not massively altered by the presence of graphene-related materials (GRMs) in the synthetic medium.

Zn-Cu bimetallic gas diffusion electrodes for electrochemical reduction of CO2 to ethylene

The application of renewable energy to drive the electroreduction of carbon dioxide (CO2) into valuable compounds serves as a means of energy storage and simultaneously aids in the mitigation of climate change. In this study, a bimetallic catalyst consisting of Zinc and Copper is synthesized using the Zinc-doped HKUST-1 metal-organic framework. The catalyst is then fabricated on gas diffusional electrode and investigated in both H-Cell and Flow cell configurations for electrochemical CO2 reduction reaction (ECO2RR). In the H-Cell, the catalysts that have been developed exhibit an ethylene faradaic efficiency (FE) up to 40 % when operated at a potential of −0.8 V relative to the reversible hydrogen electrode (RHE). The Zn-Cu bimetallic gas diffusion electrodes (GDE) exhibit an impressive ethylene FE up to 45 % when operating at a current density of −200 mA cm−2 at −1.0 V versus RHE in the flow cell. This research offers valuable insights into the strategic development of copper-based bimetallic catalysts with the aim of enhancing the efficiency of electrochemical reduction of CO2 to yield multicarbon compounds.

Effective heat transfer associated with CO2 and CH4 adsorption on HKUST-1 metal-organic framework deposited in situ on heat exchanger

The aim of this study was to analyze the heat transfer properties a copper heat exchanger with the in situ synthesized HKUST-1 metal-organic framework (MOF). For this purpose, a dedicated reactor was constructed to enable the direct measurements of heat of adsorption of CO2 and CH4, that accompanies the dynamic course of these processes. In parallel, CO2 and CH4 adsorption isotherms were determined at various temperatures and the heat of adsorption was calculated by an indirect method. Temperature changes on the heat exchanger as a result of cyclic adsorption/desorption processes of CO2 and CH4 on the HKUST-1 layer were registered, and the results of adsorption heat by direct and indirect methods were compared. Comparing the results of indirect and direct measurements of temperature changes accompanying CO2 adsorption, a difference of 19 % was obtained. In the case of CH4 adsorption, the results obtained by the two methods differed by 22 %. Based on the experimental results, it was proven that HKUST-1 synthesized in situ on a copper heat exchanger has improved heat transfer properties. The proposed concept of MOF layer on heat exchanger allows for efficient thermal stimulation of sorption processes and simultaneous MOF regeneration while minimizing the thermal energy supplied to the system.

The effect of copper(II) salt precursor on physicochemical properties of HKUST-1 MOFs and their application as adsorbents of Cr(III) ions from aqueous solutions

In this work HKUST-1 was synthesized using 4 different copper(II) salts precursors to investigate their effect on the physicochemical properties of obtained metal-organic frameworks (MOFs). To allow greener synthesis of HKUST-1, N,N-dimethylformamide-free (DMF-free) procedure was employed. Copper nitrate, copper sulphate, copper acetate, and copper chloride were selected for the syntheses. The yield of obtained products changed in order acetate>nitrate>sulfate, whereas synthesis with copper chloride yielded no product after 24 h at 110 °C hydrothermal treatment. The obtained materials were characterized by means of XRD, N2 adsorption−desorption at 77 K, TG, SEM, FTIR, DLS, and XPS. MOFs were further investigated as adsorbents of Cr(III) ions from aqueous solutions. Adsorption kinetics and adsorption statics models were correlated with the experimental data to gain a better understanding of the adsorption effectiveness.

Manipulating the HKUST-1 metal-organic framework into a visible light photocatalyst with more than one-hundred-fold increase in degradation of an anionic dye

Quasi-metal-organic frameworks (Q-MOFs) combine the advantages of metal-organic frameworks (MOFs) and metal oxides into one system. Formed metal oxides during thermal treatment of a quasi-MOF create specific heterojunctions and the diffusion of reactants into its accessible metal active centers promotes adsorption and photocatalytic degradation activities. In this work, a ternary heterojunction type-II/type-II photocatalyst was prepared with the combination of TiO2 and HKUST-1 and then its conversion to quasi-MOF (Cu2O formed in situ during the thermal process). The designed Quasi-TiO2@HKUST (QTH) photocatalytic composite demonstrates 120 times higher adsorption and degradation of Rose Bengal dye than HKUST-1. As a result, at ambient temperature without pH adjustments, 1870 mg. g−1 of contaminants was adsorbed and degraded. It took less than 30 min with a 95 % degradation rate under sunlight to complete the photocatalytic degradation. By using this method, it is possible to produce highly effective ternary heterojunctions by a simple method.

Metal-organic framework integrated surface-engineered polyelectrolyte membranes enhancing tetrahydrofuran dehydration

BackgroundEnhancing composite membrane performance is crucial for industrial separation processes. Integrating metal-organic frameworks (MOFs) into membranes offers a promising strategy. We introduce a novel approach by integrating HKUST-1 MOF within a polyelectrolyte matrix to improve membrane efficiency. MethodsA layer-by-layer self-assembly technique on a hydrolyzed polyacrylonitrile support integrates HKUST-1 into a polyelectrolyte matrix. Polyethyleneimine (PEI) and polyacrylic acid (PAA) form the polyelectrolyte layer through electrostatic interactions. The incorporation of HKUST-1 within the PEI matrix enhances separation efficiency, particularly in tetrahydrofuran dehydration, with optimal conditions using 100 ppm of HKUST-1 and forming 2 bilayers. Significant findingsUnder optimal conditions, the resulting membrane exhibits exceptional performance. It demonstrates a permeation flux of 1442.30 g∙m−2∙h−1, a water concentration in the permeate of 98.0 wt%, and a separation factor of 440. The modified membrane also shows remarkable stability across varying temperatures (25–55 °C) and tetrahydrofuran concentrations in the feed (10–90 wt%) during long-term testing. These findings highlight the membrane's potential for enhancing separation processes in the chemical industry.

3D monolithic composites TiO2/HKUST-1/RGO@melamine foam with improved surface mass transfer for efficient photocatalytic degradation of toluene gas

Currently, photocatalytic technology mostly uses powdered TiO2 catalysts, which are not conducive to recycling, limit the contact between volatile organic compounds (VOCs) and the photocatalyst, and result in lower mass transfer efficiency in gas-solid reactions. Meanwhile, TiO2 catalysts including the electrospun TiO2 nanofibers with hydrophilic surfaces are not favorable for the infiltration and adsorption of non-polar VOCs. To solve these problems, in this work, the monolithic composites TiO2/HKUST-1/RGO@melamine foam (named MRTH) with improved surface mass transfer composed of metal-organic framework (HKUST-1), graphene oxide (GO) and electrospun TiO2 nanofibers was designed. The metal-organic framework HKUST-1 plays a role in promoting the adsorption of toluene, while the reduced graphene oxide (RGO) facilitates the infiltration of non-polar molecules on the surface of the composite and has better electron transport capability. A type II heterojunction between the electrospun TiO2 nanofibers and HKUST-1 formed in the monolithic composites suppresses the recombination of electron-hole pairs and extends their lifespan. Comparing with the bare electrospun TiO2 nanofibers, the MRTH foam composites exhibit a wider light absorption range, hydrophilic and oleophobic properties and a higher separation efficiency of photogenerated carriers. In 90 min of dark adsorption, the removal rate of toluene over MRTH-8 was 52.32 %, while under irradiation by xenon lamp for 150 min, the removal rate over MRTH-8 reached 90.15 %. The amount of monolithic foam composites can also be easily adjusted in the reactor to achieve the best possible removal of the contaminant. The prepared composite materials have been characterized in detail, and the possible mechanisms have also been discussed. The foam composites prepared in this work have high catalytic activity and gas-solid reaction mass transfer efficiency, so they have wide practical application prospects in the field of VOCs abatement.

Synthesis and Characteristics of Ionic Liquid-Implanted HKUST-1 Metal–Organic Frameworks for Transforming Heat into Extraordinary Water Transfer

Synthesis and Characteristics of Ionic Liquid-Implanted HKUST-1 Metal–Organic Frameworks for Transforming Heat into Extraordinary Water Transfer

Carbon (IV) oxide adsorption efficiency of functionalized HKUST-1, IRMF-1, and UiO-66 metal organic frameworks

The ever-increasing consumption of fossil fuels to meet up with the global economic and industrial energy needs has led to climatic change due to uncontrollable emission of a major greenhouse gas (CO2). As a way of mitigating the amount of CO2 in the atmosphere, search for effective and efficient solid adsorbent has been at the front burner of current scientific research. A class of solid adsorbent known as metal organic frameworks (MOFs) have demonstrated immense potentials for CO2 adsorption due to its porous, high thermal and chemical stability, high versatility and ease of production. Upon functionalization, the adsorption efficiency of this class of materials was found to improve tremendously. In this review, the CO2 capture and sequestration potentials of three MOFs (UiO-66, HKUST-1, and MOF-5) and their composites were investigated in the search for economical, stable, and highly selective novel adsorbents for CO2 adsorption.

Miniature Optical Fiber Fabry-Perot Interferometer Based on a Single-Crystal Metal-Organic Framework for the Detection and Quantification of Benzene and Ethanol at Low Concentrations in Nitrogen Gas.

This study reports for the first time, to the best of our knowledge, a real-time detection of ultralow-concentration chemical gases using fiber-optic technology, combining a miniaturized Fabry-Perot interferometer (FPI) with metal-organic frameworks (MOFs). The sensor consists of a short and thick-walled silica capillary segment spliced to a lead-in single-mode fiber (SMF), housing a tiny single crystal of HKUST-1 MOF, imparting chemoselectivity features. Ethanol and benzene gases were tested, resulting in a shift in the FPI interference signal. The sensor demonstrated high sensitivity, detecting ethanol gas concentrations (EGCs) with a sensitivity of 0.428 nm/ppm between 24.9 and 40.11 ppm and benzene gas concentrations (BGCs) with a sensitivity of 0.15 nm/ppm between 99 and 124 ppm. The selectivity study involved a combination of three ultralow concentrations of ethanol, benzene, and toluene gases, revealing an enhancement factor of 436% for benzene and 140% for toluene, attributed to the improved miscibility of these conjugated ring molecules with the alkane chains of the ethanol-modified HKUST-1. Experimental tests confirmed the sensor's viability, demonstrating significantly improved response time and spectral characteristics through crystal polishing, indicating its potential for quantifying and detecting chemical gases at ultralow concentrations. This technology may prevent energy resource losses, and the sensor's small size and robust construction make it applicable in confined and hazardous locations.

Effect of HKUST-1 metal–organic framework in root and shoot systems, as well as seed germination

The seed germination, as well as root and shoot growth effect of HKUST-1 MOF, and its derived linear polymer ([Cu2(OH)(BTC)(H2O)]n·2nH2O) were herein examined. These effects were studied for seven higher plant species: sweet corn (Zea mays L.), black bean (Phaseolus vulgaris L.), tomato (Solanum lycopersicum L.), lettuce (Lactuca sativa L.), celosia (Celosia argentea L.), Aztec marigold (Tagetes erecta L.), and gypsophila (Gypsophila paniculata L.). The studied concentrations of MOFs were 10, 100, 500, or 1000 mg/L, enhancing the percentage of germination and growth of plants in most species. In general, the growth of the root is lower compared to the controls due to the capacity of the MOF to adsorb water and provide micronutrients such as C, O, and Cu, acting as a reserve for the plant. Shoot system growths are more pronounced with HKUST-1 compared with control, and linear polymer, due to the 3D structure adsorbs major water contents. It was found that all studied species are tolerant not only to Cu released from the material, but more evident to Cu structured in MOFs, and this occurs at high concentrations compared to many other systems. Finally, copper fixation was not present, studied by EDX mapping, banning the possibility of metallic phytotoxicity to the tested cultivars.

Physical vapor deposition of an oriented metal–organic framework HKUST-1 thin film on an insulating substrate

This study reports the synthesis of a (111)-oriented HKUST-1 ([Cu3(BTC)2], BTC = 1,3,5-benzenetricarboxylate) thin film on an insulating glass substrate using a combination of physical vapor deposition and solvent vapor annealing.

Mechanochemical synthesis and application of mixed-metal copper–ruthenium HKUST-1 metal–organic frameworks in the electrocatalytic oxygen evolution reaction

Novel electrode materials for electrocatalytic hydrogen generation are investigated for increasing the activity of expensive noble-metal components.

Spray synthesis of hierarchical porous metal-organic framework HKUST-1 with soft templates and methylene blue adsorption performance

We synthesize hierarchical porous HKUST-1 (HP-HKUST-1) with micropores, mesopores, and macropores using the spray synthesis and soft template methods. We utilize two types of structure-directing agents (SDAs), namely cetyltrimethylammonium bromide and citric acid for C-HKUST-1 and triblock copolymer P123 for P-HKUST-1. Paq-HKUST-1 is successfully synthesized using only water as the solvent. The volumes of the mesopores and macropores are changed by the amounts of SDAs. The highest values are: 0.78 and 0.30 cm3/g for C-HKUST-1; 0.44 and 0.38 cm3/g for P-HKUST-1; and 0.30 and 0.23 cm3/g for Paq-HKUST-1, respectively. HP-HKUST-1 shows high methylene blue (MB) adsorption rates and capacities of over 700 mg/g owing to its HP structure. In particular, C-HKUST-1 exhibits a rate constant of 19.7 mg/mg min for MB adsorption based on the pseudo-second-order adsorption kinetic model. This rate constant is 10 times higher than that of batch-synthesized HKUST-1. Furthermore, HP-HKUST-1 exhibits good stability for reuse as an MB adsorbent.

Test Bench Development and Application to a Parametric Experimental Study on the Dynamic Adsorption Capacity of Noble Gases (Kr, Xe) in the Metal–Organic Framework HKUST-1

Test Bench Development and Application to a Parametric Experimental Study on the Dynamic Adsorption Capacity of Noble Gases (Kr, Xe) in the Metal–Organic Framework HKUST-1

An all-glass based micro gas chromatographic column for light hydrocarbon separation with HKUST-1 as stationary phase

BackgroundThe gas chromatography column is one of the key components of the gas chromatograph and typically be miniaturized using micro-electro-mechanical system (MEMS) technology. Due to the limited area of the Si wafer, the column length of micro gas chromatographic column (μGCC) is usually much smaller than that of commercial chromatographic columns. Therefore, it is always difficult to use μGCCs to separate small molecule gas components such as light hydrocarbons. More importantly, the heterogeneous microchannel surface formed by silicon glass bonding causes uneven stationary phase coating, further preventing the improvement of separation performance. ResultsIn this paper, a novel all-glass based μGCC with 2 m length for the separation of light hydrocarbons is proposed. The microchannels of the μGCC were directly prepared in the glass substrate by ultrafast laser assisted chemical etching (ULAE). The all-glass microchannels make the coating of the hydrophilic metal-organic frameworks (MOFs) stationary phase continuously because of the homogeneous material composition. Therefore, a widely used copper based hydrophilic MOFs HKUST-1 was used as stationary phase for coating and testing. The test results show that the μGCC which is an open tubular column can realize the baseline separation of light hydrocarbons at 100 °C. And the resolution of difficult separated compounds, methane and ethane, can reach 12.98, which is 201.86 % higher than the silica-based monolithic capillary column in the relevant research. The resolution of ethane and ethylene reaches 6.81 at 120 °C. SignificanceThe μGCC fabricated by ULAE method is composed of all-glass and has the uniform stationary phase coating because of the homogeneous microchannel surface which greatly improve the separation performance, resulting in a large resolution for methane and ethane. The all-glass μGCC has broad application prospects in light hydrocarbon separation.

Adsorption of methane and ethane on HKUST-1 metal–organic framework and mesoporous silica composites

Composite materials HKUST-1@MCM-41 and HKUST-1@ BPS based on metal–organic framework HKUST-1 [Cu3(btc)2, btc = benzene-1,3,5-tricarboxylate] and silicas, i.e., mesoporous MCM-41 and biporous BPS with a bimodal mesopore size distribution, were prepared by one-step direct growth technique. Methane and ethane adsorption isotherms were measured for the HKUST-1@MCM-41 and HKUST-1@BPS composites in a wide pressure range for the first time. The silica porous structure significantly affects the content and location of HKUST-1 crystallites in these host matrices, and thereby the adsorption selectivities of the composites.

Electrochemical Sensors Based on Metal-Organic Framework and Conductive Polymer HKUST-1@PANI for High-Performance Detection of Lead Ions

In this research a highly microporous Cu-BTC (denoted as HKUST-1) was synthesized using a simple and rapid synthesis room temperature method. The as-prepared HKUST-1 obtained at room temperature for 10 min exhibited a very high Brunauer–Emmett–Teller (BET) surface area of 1875 m2/g, pore volume (Vp) of 0.789 cm3/g, and average micropore size of 7.84 Å. Based on this product, we successfully fabricated a conductive electrochemical sensor HKUST-1@PANI by polymerizing a conductive polyaniline polymer (PANI) around the metal-organic framework HKUST-1. Fourier transform infrared (FTIR) spectra, X-ray diffraction pattern (XRD) support the formation of HKUST-1@PANI. Furthermore, scanning electron microscopy (SEM) studies confirmed that PANI uniformly covered the surface of HKUST-1. We used the resulting material to build a new electrochemical sensor for the reliable detection of lead ions. The electrochemical response of the developed sensor towards ions was evaluated using differential pulse voltammetry (DPV). Under optimized conditions, linear detection was reproducible over the Pb2+ concentration range from 0.005 to 50 μM with a minimum detection limit of 5 nM. The sensor is practically usable in a wide variety of environments, as it is virtually immune to interference from other coexisting ions.

Pd@HKUST-1@Cu(II)/CMC composite bead as an efficient synergistic bimetallic catalyst for Sonogashira cross-coupling reactions

We fabricated an efficient Pd@HKUST-1@Cu(II)/CMC composite bead catalyst through an innovative strategy based on the unique properties of metal-organic frameworks (MOFs) and carboxymethylcellulose (CMC). In this strategy, HKUST-1 MOFs were grown in-situ on the surface of micrometer-sized Cu-based CMC beads (Cu(II)/CMC), then Pd(II) ions were incorporated into the pores of the MOF and further be partially reduced to Pd(0) NPs, which is an active species for oxidative addition with aryl halides in Sonogashira reactions. The micron-sized Cu(II)/CMC beads were formed through inter/intramolecularly crosslinking facilitated by Cu(II) ions, which was achieved by the metathesis of Cu(II) with numerous carboxylic groups of CMC. Such Cu(II)/CMC bead offers many Cu(II) ions as interaction sites for in-situ nucleation and growth of HKUST-1 MOFs. The architecture and composition of the prepared Pd@HKUST-1@Cu(II)/CMC composite were fully verified by various techniques such as FTIR, XRD, TGA, BET, XPS, SEM, TEM, EDX, and elemental mapping analysis. This novel composite bead was applied as an efficient and reusable heterogeneous Pd/Cu bimetallic catalyst for Sonogashira reactions, decarbonylative Sonogashira reaction, and Sonogashira cyclization tandem reactions. The catalyst is readily isolated by simple filtration, and can be reused for five consecutive runs with retaining its activity and structural integrity.