Carbon dioxide capture-related gas adsorption and separation in metal-organic frameworks

Development of highly permselective Mixed Matrix Membranes comprising of polyimide and Ln-MOF for CO2 capture

Mixed Matrix Membranes (MMMs) with hybrid organic-inorganic characteristics offer a strong alternative to traditional polymer-based membranes to reduce the trade-off between gas permeability and selectivity. This work incorporated lanthanum-Metal Organic Frameworks in the Matrimid to fabricate MMMs. To understand the effects of nano-filler on membranes' morphology, porosity, thermal stability, and chemical composition, MMMs were fabricated with three different loadings of nano-filler, i.e., 10, 20 and 30 wt%. The selectivity and permeability of CH₄, CO₂, and N₂ gases through MMMs were investigated at 10 bar pressure and temperatures ranging from 25 to 55 °C. All MMMs exhibited enhanced CO₂ permeation with increased nano-filler loading because the porous nano-filler provided additional channels and fractional free volume in the polymer matrix. The 30 wt% loaded membrane showed a 183% increase in permeability of CO₂ than neat membrane. With increasing nano-filler loading, the selectivity of MMMs increased from 34.1 to 48.45 for CO₂/N₂ and from 36.2 to 54.67 for CO₂/CH₄, confirming the absence of membrane defects, improved filler/polymer interface, and excellent dispersion of nano-filler in the polymer matrix. The results proved that these membranes could be further used for gas separation industrial applications.

A Review on Cyanide Gas Elimination Methods and Materials

Cyanide gas is highly toxic and volatile and is among the most typical toxic and harmful pollutants to human health and the environment found in industrial waste gas. In the military context, cyanide gas has been used as a systemic toxic agent. In this paper, we review cyanide gas elimination methods, focusing on adsorption and catalysis approaches. The research progress on materials capable of affecting cyanide gas adsorption and catalytic degradation is discussed in depth, and the advantages and disadvantages of various materials are summarized. Finally, suggestions are provided for future research directions with respect to cyanide gas elimination materials.

Experimental and theoretical study of the effect of different functionalities of graphene oxide/polymer composites on selective CO2 capture

There is a constant need for versatile technologies to reduce the continuously increasing concentration of CO₂ in the atmosphere, able to provide effective solutions under different conditions (temperature, pressure) and composition of the flue gas. In this work, a combination of graphene oxide (GO) and functionalized waterborne polymer particles was investigated, as versatile and promising candidates for CO₂ capture application, with the aim to develop an easily scalable, inexpensive, and environmentally friendly CO₂ capture technology. There are huge possibilities of different functional monomers that can be selected to functionalize the polymer particles and to provide CO₂-philicity to the composite nanostructures. Density functional theory (DFT) was employed to gain a deeper understanding of the interactions of these complex composite materials with CO₂ and N₂ molecules, and to build a basis for efficient screening for functional monomers. Estimation of the binding energy between CO₂ and a set of GO/polymer composites, comprising copolymers of methyl methacrylate, n-butyl acrylate, and different functional monomers, shows that it depends strongly on the polymer functionalities. In some cases, there is a lack of cooperative effect of GO. It is explained by a remarkably strong GO-polymer binding, which induced less effective CO₂-polymer interactions. When compared with experimental results, in the cases when the nanocomposite structures presented similar textural properties, the same trends for selective CO₂ capture over N₂ were attained. Besides novel functional materials for CO₂ capture and a deeper understanding of the interactions between CO₂ molecules with various materials, this study additionally demonstrates that DFT calculations can be a shorter route toward the efficient selection of the best functionalization of the composite materials for selective CO₂ capture.

A Coordination Network Featuring Two Distinct Copper(II) Coordination Environments for Highly Selective Acetylene Adsorption

Single crystals of 2D coordination network {Cu2 L2  ⋅ (DMF)3 (H2 O)3 }n (1-DMF) were prepared by reaction of commercial reagents 3-formyl-4-hydroxybenzoic acid (H2 L) and Cu(NO3 )2 in dimethylformamide (DMF). The single-crystal structure shows two distinct Cu(II) coordination environments arising from the separate coordination of Cu(II) cations to the carboxylate and salicylaldehydato moieties on the linker, with 1D channels running through the structure. Flexibility is exhibited on solvent exchange with ethanol and tetrahydrofuran, while porosity and the unique overall connectivity of the structure are retained. The activated material exhibits type I gas sorption behaviour and a BET surface area of 950 m2  g-1 (N2 , 77 K). Notably, the framework adsorbs negligible quantities of CH4 compared with CO2 and the C2 Hn hydrocarbons. It exhibits exceptional selectivity for C2 H2 /CH4 and C2 H2 /C2 Hn , which has applicability in separation technologies for the isolation of C2 H2 .

Self-Assembly Bifunctional Tetranuclear Ln2Ni2 Clusters: Magnetic Behaviors and Highly Efficient Conversion of CO2 under Mild Conditions

A series of heterometallic tetranuclear clusters, Ln₂Ni₂(NO₃)₄L₄(μ₃-OCH₃)₂·2(CH₃CN) (Ln = Gd(1), Tb(2), Dy(3), Ho(4), Er(5); HL = methyl 3-methoxysalicylate), were synthesized solvothermally. The intramolecular synergistic effect of two metal centers of Ln(III) and Ni(II) and the exposed multimetallic sites serving as Lewis acid activators greatly increase the efficiency of the CO₂ conversion, and the yield for cluster 3 can be achieved at 96% at atmospheric pressure and low temperature. In particular, the self-assembly multimetal center with polydentate ligand shows good generality and enhanced recyclability. The design of such 3d-4f heterometallic clusters provides an effective strategy for the conversion of CO₂ under greener conditions. Meanwhile, magnetic investigations indicate that cluster 1 is a good candidate for magnetic refrigerant materials with a relatively large magnetocaloric effect (MCE) (-ΔS_m = 28.5 J kg^-1 K^-1 at 3.0 K and 7.0 T), and cluster 3 shows single-molecular magnet behavior under zero dc field. Heterometallic clusters with special magnetic properties and good catalytic behavior for the conversion of CO₂ are rare. Thus, they are potential bifunctional materials applied in practice.

CO2 Capture from High-Humidity Flue Gas Using a Stable Metal–Organic Framework

The flue gas from fossil fuel power plants is a long-term stable and concentrated emission source of CO2, and it is imperative to reduce its emission. Adsorbents have played a pivotal role in reducing CO2 emissions in recent years, but the presence of water vapor in flue gas poses a challenge to the stability of adsorbents. In this study, ZIF-94, one of the ZIF adsorbents, showed good CO2 uptake (53.30 cm3/g), and the calculated CO2/N2 (15:85, v/v) selectivity was 54.12 at 298 K. Because of its excellent structural and performance stability under humid conditions, the CO2/N2 mixture was still well-separated on ZIF-94 with a separation time of 30.4 min when the relative humidity was as high as 99.2%, which was similar to the separation time of the dry gas experiments (33.2 min). These results pointed to the enormous potential applications of ZIF-94 for CO2/N2 separation under high humidity conditions in industrial settings.

Self-assembly of octanuclear Ln(III)-based clusters: their large magnetocaloric effects and highly efficient conversion of CO2

The design and construction of high-nuclear lanthanide clusters with fascinating topology and functional properties have been an active area of research, however, the development of an effective approach for obtaining high-nuclear lanthanide clusters with multifunctional properties is still extremely difficult. Up to now, a systematic approach for guiding the further expansion of Ln(III)-based clusters showing good functional properties is lacking. Herein, we design and synthesize a polydentate Schiff base ligand (HL), which reacts with β-diketonate salts Ln(acac)₃·2H₂O, and a series of Ln₈ clusters [Ln₈(acac)₆(L)₂(μ₃-O)₆(μ₂-C₂H₅O)₄(μ₂-Hacac)₂]·2CH₃CN (Ln(III) = Gd (1), Dy (2), and Ho (3); HL = pyridine-2-carboxylic acid (5-hydroxymethyl-furan-2-ylmethylene)-hydrazide, Hacac = acetylacetone) have been successfully synthesized. Single-crystal X-ray diffraction studies reveal that clusters 1-3 are isostructural and can be viewed as a Ln₈ core bridged by eighteen μ₂-O atoms, six μ₃-O atoms and two μ₄-O atoms. Magnetic studies show that cluster 1-Gd8 displays a large magnetocaloric effect with -ΔS_m = 46.14 J kg^-1 K^-1 (T = 2.0 K and ΔH = 7.0 T); cluster 2-Dy8 exhibits single-molecule magnet behavior under zero-field conditions. It is worth mentioning that the -ΔS_m of cluster 1-Gd8 is larger than that of most reported polynuclear Gd(III)-based clusters; the 2-Dy8 cluster is one of the rare polynuclear Ln_n SMMs (n ≥ 8) under zero dc field. Importantly, these Ln(III)-based clusters (1-3) can catalyze the cycloaddition of CO₂ with epoxides with high efficiency under mild conditions; and cluster 1-Gd8 as a catalyst could be reused at least three times without obvious loss of catalytic performance.

Synthesis and CO2 Capture of Porous Hydrogel Particles Consisting of Hyperbranched Poly(amidoamine)s

We successfully synthesized new macroporous hydrogel particles consisting of hyperbranched poly(amidoamine)s (HPAMAM) using the Oil-in-Water-in-Oil (O/W/O) suspension polymerization method at both the 50 mL flask scale and the 5 L reactor scale. The pore sizes and particle sizes were easily tuned by controlling the agitation speeds during the polymerization reaction. Since O/W/O suspension polymerization gives porous architecture to the microparticles, synthesized hydrogel particles having abundant amine groups inside polymers exhibited a high CO2 absorption capacity (104 mg/g) and a fast absorption rate in a packed-column test.

Considerations on Gated CO2 Adsorption Behavior in One-Dimensional Porous Coordination Polymers Based on Paddlewheel-Type Dimetal Complexes: What Determines Gate-Opening Temperatures?

Low-dimensional coordination polymers such as one-dimensional chains often exhibit gated guest sorption accompanying structural transition at a temperature (T_G), which is associated with an external pressure of the guest (P_G) characteristic to the material and guest used. This phenomenon can be evaluated using the Clausius-Clapeyron relationship with the equation d(ln P_G)/d(1/T_G) = ΔH_G/R, where ΔH_G and R are the transition enthalpy and gas constant, respectively. In this study, gated CO₂ adsorption behavior was investigated in a one-dimensional chain based on a benzoate-bridged paddlewheel diruthenium(II,II) complex with a phenazine (phz) linker, [Ru₂(p-MeOPhCO₂)₄(phz)] (1; p-MeOPhCO₂^- = p-anisate). Surprisingly, 1 underwent gate opening (GO)/closing (GC) at a much higher T_G, e.g., 385 K for GC, under P_CO2 = 100 kPa than those previously reported for such chain compounds, which usually appeared in the temperature range of 200-270 K. The transition entropy ΔS_G in each system plays a key role in shifting T_G; 1 results in a much smaller |ΔS_G| in the series. Only 1 produced a CO₂-accessible two-dimensional topological pore in its CO₂-adsorbed phase 1⊃CO₂, whereas the others reported previously produced one-dimensional or discrete topological pores for CO₂ accommodation, strongly reflecting the degree of freedom of CO₂ molecules in pores, which is related to ΔS_G.

Effect of Pore Structure on CO2 Adsorption Performance for ZnCl2/FeCl3/H2O(g) Co-Activated Walnut Shell-Based Biochar

Walnut shell is a very potential biochar precursor because of its wide source, low cost, and easy structure modification. In this paper, the co-activation method of FeCl3, ZnCl2 and H2O(g) was adopted to prepare walnut shell-based biochar with high microporosity and the effect of pore structure on CO2 adsorption performance at different temperatures was investigated. The prepared biochar had a larger specific surface area (2647.8 m2 g−1), satisfactory micropore area (2008.7 m2 g−1) and high total pore volume (2.58 cm3 g−1). At 273 K and 298 K, its CO2 adsorption capacity was 4.79 mmol g−1 and 3.20 mmol g−1, respectively. Particularly, CO2 adsorbed uptake on biochar was strongly sensitive to their narrow micropore volume, instead of the total specific surface area, total pore volume, and micropore specific surface area. The optimal pore size beneficial for CO2 adsorption was 0.33–0.82 nm at 273 K, but the optimal pore size was 0.33–0.39 nm at 298 K. It provides theoretical guidance for future material preparation and selection, and FeCl3, ZnCl2 and H2O(g) may be effective biochar activators.

Modular Assembly of Isostructural Mixed-Ligand Uranyl Coordination Polymers Based on a Patterning Strategy

Controlling the orderly assembly of molecular building blocks for the formation of the desired architectural, chemical, and physical properties of the resulting solid-state materials remains a long-term goal and deserves to be examined. In this work, we propose a patterning strategy for modular assembly and structural regulation of mixed-ligand uranyl coordination polymers (CPs) through the combination of couples of organic ligands with complementary molecular geometry and well-matched coordination modes. By using a 5-(p-tolyldiazenyl)isophthalic acid ligand (H₂ptdi) with different rigid linear bicarboxylic acid linkers to construct a well-defined ladder-like pattern, five novel isostructural uranyl coordination polymers, [(UO)₂(ptdi)(bdc)_0.5](dma) (1), [(UO)₂(ptdi)(bpdc)_0.5](dma) (2), [(UO)₂(ptdi)(tpdc)_0.5](dma) (3), [(UO)₂(ptdi)(ndc)_0.5](dma) (4), and [(UO)₂(ptdi) (pdc)_0.5](dma) (5) {H₂bdc, 1,4-dicarboxybenzene; H₂bpdc, 4,4'-biphenyldicarboxylic acid; H₂tpdc, terphenyl-4,4″-dicarboxylic acid; H₂ndc, 2,6-naphthalenedicarboxylic acid; H₂pdc, 1,6-pyrenedicarboxylic acid; [dma]⁺, [(CH₃)₂NH₂]⁺}, were successfully synthesized. Structural analysis reveals that 1-5 have similar ladder-like units but different sizes of one-dimensional nanochannels and interlayer spacing due to the different lengths and widths of the linkers. Because of the changes in interlayer spacing of these isostructural cationic frameworks, differences in the performance of Eu³⁺ ion exchange with [dma]⁺ are observed. Moreover, those compounds with high phase purity have been further characterized by thermogravimetric analysis, infrared spectroscopy, and luminescence spectroscopy, element analysis, PXRD and UV spectroscopy. Among them, compound 3 with strong fluorescence can selectively detect Fe³⁺ over several competing metal cations in aqueous solution. This work not only provides a feasible patterning method for effectively regulating the modular synthesis of functional coordination polymers but also enriches the library of uranyl-based coordination polymers with intriguing structures and functionality.

Lead(II)-Azido Metal–Organic Coordination Polymers: Synthesis, Structure and Application in PbO Nanomaterials Preparation

The current study aims to explain recent developments in the synthesis of Pb(II)-azido metal-organic coordination polymers. Coordination polymers are defined as hybrid materials encompassing metal-ion-based, organic linkers, vertices, and ligands, serving to link the vertices to 1D, 2D, or 3D periodic configurations. The coordination polymers have many applications and potential properties in many research fields, primarily dependent on particular host–guest interactions. Metal coordination polymers (CPs) and complexes have fascinating structural topologies. Therefore, they have found numerous applications in different areas over the past two decades. Azido-bridged complexes are inorganic coordination ligands with higher fascination that have been the subject of intense research because of their coordination adaptability and magnetic diversity. Several sonochemical methods have been developed to synthesize nanostructures. Researchers have recently been interested in using ultrasound in organic chemistry synthetics, since ultrasonic waves in liquids accelerate chemical reactions in heterogeneous and homogeneous systems. The sonochemical synthesis of lead–azide coordination compounds resulted from very fantastic morphologies, and some of these compounds are used as precursors for preparing nano lead oxide. The ultrasonic sonochemistry approach has been extensively applied in different research fields, such as medical imaging, biological cell disruption, thermoplastic welding, food processing, and waste treatment. CPs serve as appropriate precursors for preparing favorable materials at the nanoscale. Using these polymers as precursors is beneficial for preparing inorganic nanomaterials such as metal oxides.

Challenges, Opportunities and Future Directions of Membrane Technology for Natural Gas Purification: A Critical Review

Natural gas is an important and fast-growing energy resource in the world and its purification is important in order to reduce environmental hazards and to meet the required quality standards set down by notable pipeline transmission, as well as distribution companies. Therefore, membrane technology has received great attention as it is considered an attractive option for the purification of natural gas in order to remove impurities such as carbon dioxide (CO₂) and hydrogen sulphide (H₂S) to meet the usage and transportation requirements. It is also recognized as an appealing alternative to other natural gas purification technologies such as adsorption and cryogenic processes due to its low cost, low energy requirement, easy membrane fabrication process and less requirement for supervision. During the past few decades, membrane-based gas separation technology employing hollow fibers (HF) has emerged as a leading technology and underwent rapid growth. Moreover, hollow fiber (HF) membranes have many advantages including high specific surface area, fewer requirements for maintenance and pre-treatment. However, applications of hollow fiber membranes are sometimes restricted by problems related to their low tensile strength as they are likely to get damaged in high-pressure applications. In this context, braid reinforced hollow fiber membranes offer a solution to this problem and can enhance the mechanical strength and lifespan of hollow fiber membranes. The present review includes a discussion about different materials used to fabricate gas separation membranes such as inorganic, organic and mixed matrix membranes (MMM). This review also includes a discussion about braid reinforced hollow fiber (BRHF) membranes and their ability to be used in natural gas purification as they can tackle high feed pressure and aggressive feeds without getting damaged or broken. A BRHF membrane possesses high tensile strength as compared to a self-supported membrane and if there is good interfacial bonding between the braid and the separation layer, high tensile strength, i.e., upto 170Mpa can be achieved, and due to these factors, it is expected that BRHF membranes could give promising results when used for the purification of natural gas.

Substituent Dependence on Series of Cationic Gyroidal MOFs in utc-c Topology with High CO2 Affinity and Ultrahigh Anionic Dye Adsorption Capacity

A substituent decorating strategy for modification of the functional cavity is of great importance in the design of metal-organic frameworks (MOFs). Herein, three new isostructural cationic MOFs, [Cu₃(Xpip)₂]·NO₃·nH₂O (Xpip stands for X-substituted phenylimidazophenanthroline, where X = adm (SCNU-2), f (SCNU-3), and none for SCNU-4), have been successfully synthesized and shown gyroidal utc-c topology and large pore sizes which can be adjusted by different substituents (-N(CH₃)₂, -F, and -H). Interestingly, the differences of the substituents (sizes and proton donor/acceptor) show essential effects on the adsorption abilities of carbon dioxide and dyes, where SCNU-4 exhibits the highest CO₂ affinity and the biggest adsorption capacity for anionic dyes Fluorescein Sodium, and SCNU-3 adsorbs the largest amount (1503.6 mg/g) of Acid Fuchsin to date for the reported porous materials. The detailed studies in adsorption kinetics, adsorption isotherms, and theoretical calculation of the binding energies between the structures and dye molecules confirm that the electric properties of the frameworks (cationic) and substituents directed to the pore surface are two important factors dramatically affecting the selective dye adsorption.

Nickel metal-organic frameworks for visible-light CO2 reduction under mild reaction conditions

Photochemical CO₂ conversion into carbon fuel is a promising route to explore renewable energy and relieve climate change. However, it is still a key challenge to achieve high selectivity to CO and simultaneously achieve high conversion efficiency in photochemical CO₂ reduction. Herein, we demonstrate the effect of Ni metal centers as catalytic active sites for the photocatalytic conversion of CO₂ to CO by designing and constructing Ni metal-organic framework (Ni-MOF) materials. In pure CO₂, Ni-MOF catalyst exhibits outstanding performance for visible-light-driven reductive CO₂ deoxygenation with a high CO evolution rate of 19.13 μmol h^-1 (per 1 mg of catalyst) and CO selectivity of 91.4%, which exceeds those of most reported systems. Upon using isostructural Co-MOF as the catalyst to replace Ni-MOF, a moderate performance towards CO₂ photoreduction and low CO selectivity (40.1%) were observed, implying that the performance of CO₂ photoreduction and CO selectivity are dependent on unsaturated metal centers.

A Comparative Study of Different Sorbents in the Context of Direct Air Capture (DAC): Evaluation of Key Performance Indicators and Comparisons

Direct air capture can be based on an adsorption system, and the used sorbent (chemisorbents or physisorbents) influences process. In this work, two amine-functionalized sorbents, as chemisorbents, and three different metal organic frameworks, as physisorbents, are considered and compared in terms of some key performance indicators. This was carried out by developing a mathematical model describing the adsorption and desorption stages. An independent analysis was carried out in order to verify data reported in the literature. Results show that the equilibrium loading is a critical parameter for adsorption capacity, energy consumption, and cost. The considered metal organic frameworks are characterized by a lower equilibrium loading (10−4 mol/kg) compared to chemisorbents (10−1 mol/kg). For this reason, physisorbents have higher overall energy consumptions and costs, while capturing a lower amount of carbon dioxide. A reasonable agreement is found on the basis of the operating conditions of the Climeworks company, modelling the use of the same amine cellulose-based sorbent. The same order of magnitude is found for total costs (751 USD/tonneCO2 for our analysis, compared to the value of 600 USD/tonneCO2 proposed by this company).

Emerging Separation Applications of Surface Superwettability

Human beings are facing severe global environmental problems and sustainable development problems. Effective separation technology plays an essential role in solving these challenges. In the past decades, superwettability (e.g., superhydrophobicity and underwater superoleophobicity) has succeeded in achieving oil/water separation. The mixture of oil and water is just the tip of the iceberg of the mixtures that need to be separated, so the wettability-based separation strategy should be extended to treat other kinds of liquid/liquid or liquid/gas mixtures. This review aims at generalizing the approach of the well-developed oil/water separation to separate various multiphase mixtures based on the surface superwettability. Superhydrophobic and even superoleophobic surface microstructures have liquid-repellent properties, making different liquids keep away from them. Inspired by the process of oil/water separation, liquid polymers can be separated from water by using underwater superpolymphobic materials. Meanwhile, the underwater superaerophobic and superaerophilic porous materials are successfully used to collect or remove gas bubbles in a liquid, thus achieving liquid/gas separation. We believe that the diversified wettability-based separation methods can be potentially applied in industrial manufacture, energy use, environmental protection, agricultural production, and so on.

Recent Progress in Two-Dimensional Materials for Electrocatalytic CO2 Reduction

Electrocatalytic CO2 reduction (ECR) is an attractive approach to convert atmospheric CO2 to value-added chemicals and fuels. However, this process is still hindered by sluggish CO2 reaction kinetics and the lack of efficient electrocatalysts. Therefore, new strategies for electrocatalyst design should be developed to solve these problems. Two-dimensional (2D) materials possess great potential in ECR because of their unique electronic and structural properties, excellent electrical conductivity, high atomic utilization and high specific surface area. In this review, we summarize the recent progress on 2D electrocatalysts applied in ECR. We first give a brief description of ECR fundamentals and then discuss in detail the development of different types of 2D electrocatalysts for ECR, including metal, graphene-based materials, transition metal dichalcogenides (TMDs), metal–organic frameworks (MOFs), metal oxide nanosheets and 2D materials incorporated with single atoms as single-atom catalysts (SACs). Metals, such as Ag, Cu, Au, Pt and Pd, graphene-based materials, metal-doped nitric carbide, TMDs and MOFs can mostly only produce CO with a Faradic efficiencies (FE) of 80~90%. Particularly, SACs can exhibit FEs of CO higher than 90%. Metal oxides and graphene-based materials can produce HCOOH, but the FEs are generally lower than that of CO. Only Cu-based materials can produce high carbon products such as C2H4 but they have low product selectivity. It was proposed that the design and synthesis of novel 2D materials for ECR should be based on thorough understanding of the reaction mechanism through combined theoretical prediction with experimental study, especially in situ characterization techniques. The gap between laboratory synthesis and large-scale production of 2D materials also needs to be closed for commercial applications.

Application progress of magnetic molecularly imprinted polymers chemical sensors in the detection of biomarkers

Specific recognition and highly sensitive detection of biomarkers play an essential role in identification, early diagnosis and prevention of many diseases. Magnetic molecularly imprinted polymers (MMIPs) have been widely used to capture biomimetic receptors for targets in various complex matrices due to their superior recognition ability, structural stability, and rapid separation characteristics, which overcome the existing deficiencies of traditional recognition elements such as antibodies, aptamers. The integration of MMIPs as recognition elements with chemical sensors opens new opportunities for the development of advanced analytical devices with improved selectivity and sensitivity, shorter analysis time, and lower cost. Recently, MMIPs-chemical sensors (MMIPs-CS) have made significant progress in detection, but many challenges and development spaces remain. Therefore, this review focuses on the research progress of the sensor based on biomarker detection and introduces the surface modification of the magnetic support material used to prepare high selective MMIPs, as well as the selective extraction of target biomarkers by MMIPs from the complex biological sample matrix. Based on the understanding of optical sensors and electrochemical sensors, the applications of MMIPs-optical sensors (MMIPs-OS) and MMIPs-electrochemical sensors (MMIPs-ECS) for biomarker detection were reviewed and discussed in detail. Moreover, it provides an overview of the challenges in this research area and the potential strategies for the rational design of high-performance MMIPs-CS, accelerating the development of multifunctional MMIPs-CS.

Application of solid-state NMR techniques for structural characterization of metal-organic frameworks

Solid-state NMR can afford the structural information about the chemical composition, local environment, and spatial coordination at the atomic level, which has been extensively applied to characterize the detailed structure and host-guest interactions in metal-organic frameworks (MOFs). In this review, recent advances for the structural characterizations of MOFs using versatile solid-state NMR techniques were briefly introduced. High-field sensitivity-enhanced solid-state NMR method enabled the direct observation of metal centers in MOFs containing low-γ nuclei. Two-dimensional (2D) homo- and hetero-nuclear correlation MAS NMR experiments provided the spatial proximity among linkers, metal clusters and the introduced guest molecules. Moreover, quantitative measurement of inter-nuclear distances using solid-state NMR provided valuable structural information about the connectivity geometry as well as the host-guest interactions within MOFs. Furthermore, solid-state NMR has exhibited great potential for unraveling the structure property of MOFs containing paramagnetic metal centers.

Methods and Techniques for CO2 Capture: Review of Potential Solutions and Applications in Modern Energy Technologies

The paper presents and discusses modern methods and technologies of CO2 capture (pre-combustion capture, post-combustion capture, and oxy-combustion capture) along with the principles of these methods and examples of existing and operating installations. The primary differences of the selected methods and technologies, with the possibility to apply them in new low-emission energy technologies, were presented. The following CO2 capture methods: pre-combustion, post-combustion based on chemical absorption, physical separation, membrane separation, chemical looping combustion, calcium looping process, and oxy-combustion are discussed in the paper. Large-scale carbon capture utilization and storage (CCUS) facilities operating and under development are summarized. In 2021, 27 commercial CCUS facilities are currently under operation with a capture capacity of up to 40 Mt of CO2 per year. If all projects are launched, the global CO2 capture potential can be more than ca. 130–150 Mt/year of captured CO2. The most popular and developed indicators for comparing and assessing CO2 emission, capture, avoiding, and cost connected with avoiding CO2 emissions are also presented and described in the paper.

Inorganic Pillar Center-Facilitated Counterdiffusion Synthesis for Highly H2 Perm-Selective KAUST-7 Membranes

Fluorinated metal-organic framework materials (NbOFFIVE-1-Ni, also referred to as KAUST-7) have attracted widespread attention because of their high chemical stability and thermal stability, outstanding tolerance with water and H₂S, and high CO₂-adsorption selectivity over H₂ and CH₄. KAUST-7 was expected to be a new membrane material candidate for H₂/CO₂ separation because of the hindered permeation of CO₂ resulting from the interaction between CO₂ and (NbOF₅)^2- of the KAUST-7 framework. A highly H₂ perm-selective KAUST-7 membrane was first achieved using a novel strategy of inorganic pillar center-facilitated counterdiffusion (IPCFCD) proposed by us. The IPCFCD method not only effectively avoided the corrosion of hydrofluoric acid to α-Al₂O₃ tubes in the process of preparing KAUST-7 membranes, but also better reduced grain boundary defects because of the faster nucleation rate and resultant high crystallinity. The KAUST-7 membrane exhibited a high H₂/CO₂ separation factor (SF) of 27.30 for the 1:1 H₂/CO₂ binary gas mixture with a high H₂ permeance of 5.30 × 10^-7 mol m^-2 s^-1 Pa^-1 under ambient conditions and a slight decrease of the H₂/CO₂ SF with increasing operation temperature and presence of steam. This study highlighted the importance of pre-synthesizing inorganic pillar centers (NiNbOF₅ intermediate) and the innovation of a membrane formation process for synthesizing polycrystalline KAUST-7 membranes. Most important of all, our study provided a novel approach to overcome the challenge in fabricating metal-organic framework membranes containing corrosive reactants for the corresponding supports.

Electrochemical activation of CO2 by MOF-(Fe, Ni, Mn) derivatives of 5-aminoisophthalic acid and the thiazole group influence on its catalytic activity

The electrocatalysis of carbon dioxide using earth abundant metals and a functionalized MOF to find a sustainable process was investigated.

Post-synthetic modification of UiO-66-OH toward porous liquids for CO2 capture

A rather simple and feasible strategy to construct MOF porous liquids with low viscosities for CO2 capture.

Recent advancement in bimetallic metal organic frameworks (M’MOFs): Synthetic challenges and applications

Metal-organic frameworks (MOFs) is a burgeoning research field and has received increasing interest in recent years due to their inherent advantages of inorganic metal ions, range of organic linkers, tunable...

CO2 uptake prediction of metal–organic frameworks using quasi-SMILES and Monte Carlo optimization

The first report of quasi-SMILES-based QSPR models for CO2 capture of MOFs based on experimental data.

Recent advances on bimetallic metal-organic frameworks (BMOFs): Syntheses, applications and challenges

Bimetallic metal-organic frameworks (MOFs) possess two different metal ions as nodes in their molecular frameworks. They are prepared by either using one-pot syntheses wherein different metals are mixed with suitable...

One step synthesis of a bimetallic (Ni and Co) metal–organic framework for the efficient electrocatalytic oxidation of water and hydrazine

A series of metal–organic frameworks (MOFs) with varying Ni : Co ratios are synthesized by an easy one-step solvothermal method using trimesic acid as an organic linker.

Vapor-assisted crystallization of in situ glycine-modified UiO-66 with enhanced CO2 adsorption

Vapor consisting of DMF and HCl promotes crystallization of in situ glycine-modified UiO-66.

Benign Synthesis of Metal-Organic Framework (MIL-101-Cr) and Evaluation of Carbon-dioxide Adsorption Behaviour Employing Adsorption Isotherm Models

BACKGROUND

In today's world, rising temperature due to global warming is caused by higher concentration of carbon dioxide (CO₂ ) emissions in the atmosphere. Metal-Organic Framework (MOF) materials have Objective: The purpose of this work is to prepare metal-organic framework materials by a benign synthesis method using water as the solvent, followed by the characterization and property evaluation for CO₂ adsorption study.

METHODS

MIL-101-Cr metal-organic framework and its derivatives with alkali ion dopants were prepared by benign hydrothermal synthesis route, which were characterized by powder X-ray diffraction method. The adsorption isotherms of CO2 for MIL-101-Cr and its derivatives were studied to comprehend the influence of alkali dopants on CO2 sorption behaviour. The equilibrium uptakes of CO2 were further evaluated by fitting the isotherms with Langmuir, Toth and Dubinin - Astakohv adsorption models to determine the adsorption parameters.

RESULTS

The crystalline structural integrity of MIL-101-Cr is not affected by doping with alkali ions. The isosteric heat of CO2 adsorption is diminished with an increase in alkali dopant size, while the induced surface structural heterogeneity increases with increasing alkali dopant size.

CONCLUSION

The equilibrium and thermodynamic parameters calculated from this study are useful for applications in carbon dioxide capture and utilization technology.

Computational Design of MOF-Based Electronic Noses for Dilute Gas Species Detection: Application to Kidney Disease Detection

The diverse chemical composition of exhaled human breath contains a vast amount of information about the health of the body, and yet this is seldom taken advantage of for diagnostic purposes due to the lack of appropriate gas-sensing technologies. In this work, we apply computational methods to design mass-based gas sensor arrays, often called electronic noses, that are optimized for detecting kidney disease from breath, for which ammonia is a known biomarker. We define combined linear adsorption coefficients (CLACs), which are closely related to Henry's law coefficients, for calculating gas adsorption in metal-organic frameworks (MOFs) of gases commonly found in breath (i.e., carbon dioxide, argon, and ammonia). These CLACs were determined computationally using classical atomistic molecular simulation techniques and subsequently used to design and evaluate gas sensor arrays. We also describe a novel numerical algorithm for determining the composition of a breath sample given a set of sensor outputs and a library of CLACs. After identifying an optimal array of five MOFs, we screened a set of 100 simplified computer-generated, water-free breath samples for kidney disease and were able to successfully quantify the amount of ammonia in all samples within the tolerances needed to classify them as either healthy or diseased, demonstrating the promise of such devices for disease detection applications.

Bimetallic Ordered Large-Pore MesoMOFs for Simultaneous Enrichment and Dephosphorylation of Phosphopeptides

Despite the fact that bimetallic metal-organic frameworks (MOFs) could afford multiple functionalities by a synergistic effect of individual metallic centers, their intrinsic microporous structure frequently restricts their wide applications with bulky molecules involved. An urgent need is consequently triggered to design bimetallic hierarchical mesoporous MOFs (mesoMOFs). Herein, Zr/Ce mesoMOFs with a uniform pore size of up to 8 nm was successfully synthesized by a copolymer template strategy with the aid of a Hoffmeister ion. The obtained Zr/Ce mesoMOFs feature high porosity, good chemical and thermal stabilities, and tunable element components, and up to 70% Zr could be incorporated into the mesoporous Ce-based framework without deteriorating its crystallinity. Thanks to the synergistic effect of inherent Ce and Zr as well as the large and open pore channels, a broad range of phosphopeptides with different molecule sizes could be effectively checked out, thanks to their simultaneous enrichment and dephosphorylation capabilities. Such an ability to efficiently concentrate phosphopeptides remained intact even in the presence of abundant non-phosphorylated species. The practical detection of phosphopeptides from human serum was also verified, prefiguring the great potentials of bimetallic large-pore mesoMOFs for the proteome applications.