Search

Global warming has been mainly attributed to the excessive release of carbon dioxide (CO 2 ) to the atmosphere. Several CO 2 capture and conversion technologies have been developed in the past few decades with their own merits and limitations. Electrochemical conversion of CO 2 is one of the most attractive techniques for combating CO 2 emissions. However, the efficacy of the electrochemical reduction of CO 2 hinges on the efficiency of the utilized materials (i.e., electrocatalysts). Metal organic frameworks (MOFs)-based materials have recently emerged as attractive tools for various applications, including the electrochemical conversion of CO 2 . Although there are some review articles on CO 2 capture and conversion using different materials, reviews focusing specifically on the electrochemical conversion of CO 2 using MOFs-based materials are still comparatively lacking. Additionally, the field of electrochemical conversion of CO 2 into valuable chemicals is currently gaining high momentum, requiring comprehensive and recent reviews, which would provide researchers/professionals with a quick and easy access to the recent developments in this rapidly evolving research area. Accordingly, this article comprehensively reviews recent studies on the electrochemical conversion of CO 2 using pristine/modified/functionalized MOFs as well as composite materials containing MOFs. Additionally, single atom catalysts (SACs) derived from MOFs and their applications for the electrochemical conversion of CO 2 has also been reviewed. Furthermore, obstacles, challenges, limitations, and remaining research gaps have been identified, and future works to tackle them have been highlighted. Overall, this review article provides valuable discussion and insights into the recent advancements in the field of electrochemical conversion of CO 2 into chemicals using MOFs-based materials., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Mixed matrix membranes (MMMs) containing metal-organic frameworks (MOFs) have been an emerging and promising membrane technology to contribute to different gas separation applications including carbon dioxide (CO 2 ) and oxygen (O 2 ) separation, because of their large surface areas and distinctive gas adsorption features. In this work, the fabrication process of Polydimethylsiloxane (PDMS)-based MMMs was reported, in which 0.5 to 2 wt.% of each type of (Cu, Ni)-based MOF-74 variants were incorporated into a PDMS matrix in order to achieve high CO 2 /N 2 , O 2 /N 2 , and CO 2 /O 2 separation efficiency. These MMMs and their nanofillers (MOF-74) were extensively characterized using scanning electron microscopy (SEM) along with Energy Dispersive X-Ray (EDX) mapping, X-ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), a single gas permeation testing system, and an ultimate tensile strength testing (UTS) unit in order to gain insight into their properties in relation to their gas separation performance. The 1 wt.% of both (Cu and Ni)-MOF-74@PDMS were selected as the most optimum MMMs due to their uniform morphology and enhanced tensile strength, which exhibited high CO 2 permeabilities of 4432 Barrer (37.9% increase) and 4288 Barrer (33.5% increase), respectively. Furthermore, in the case of 1 wt.% Ni-MOF-74@PDMS, the CO 2 /N 2 , O 2 /N 2 , and CO 2 /O 2 selectivities were also enhanced to 36.2 (141.6% increase), 3.2 (21.9% increase), and 11.25 (98.1% increase), respectively. While, in the case of 1 wt.% Cu-MOF-74@PDMS the CO 2 /N 2 and O 2 /N 2 selectivities showed an increment up-to 94.7 (531.5% increase) and 6.47 (145% increase), respectively, Whereas, at 0.5 wt.%, Cu-MOF-74@PDMS showed the best CO 2 /O 2 selectivity of 25.26 (344.7% increase)., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

[Display omitted] • A novel N,S co-doped carbon encapsulated Co 2 P anchored on MXene was fabricated. • The MZPC-9 catalyst exhibited excellent BPA removal (TOF/PMS = 291 L2 min−1 g−2). • The electron transfer-process (ETP) was the dominated reactive pathway. • The ETP-induced polymerization pathway of BPA was elucidated. The non-radical pathway dominated by the electron transfer process (ETP) has gained considerable attention for the removal of organic contaminants in persulfate-based advanced oxidation processes. Rationally designing new catalysts with optimized composition and structural merits and further elucidating the enhanced removal mechanism are of great importance. In this work, we successfully synthesized a nitrogen-sulfur co-doped carbon encapsulated cobalt phosphide (Co 2 P) on both sides of MXene nanosheets (MZPC) to degrade bisphenol A (BPA) from organic wastewater. The results indicated that BPA was degraded by 98.2 % in a mere 5 min using 0.1 g L-1 of peroxymonosulfate (PMS) and 0.05 g L-1 of the optimized catalyst (MZPC-9), exhibiting an excellent pseudo-first-order kinetics rate constant (k = 1.485 min−1). Uniformly dispersed Co 2 P nanoparticles (approximately 9.4 nm, calculated using the Scherrer equation) on both sides of MXene exhibited enhanced binding affinity with PMS, forming the MZPC-9-PMS* metastable complexes with potent oxidative capability. The resultant MZPC-9-PMS* complexes induced the polymerization reaction of BPA and achieved 81 % total organic carbon (TOC) removal. This study offers a novel perspective on the design of metal active centers to enhance the ETP-dominated non-radical pathway for pollutant degradation. [ABSTRACT FROM AUTHOR]

The two CeIV MOFs [Ce6O4(OH)4(TzTz)6] (Ce_TzTz) and [Ce6O4(OH)4(TzTz)4(PyPy)2] (Ce_TzTz_PyPy; H2TzTz = [2,2′‐bithiazole]‐5,5′‐dicarboxylic acid, H2PyPy = 2,2′‐bipyridine‐5,5′‐dicarboxylic acid) are prepared starting from a pre‐formed [Ce6] glycinate‐capped cluster. N2 isotherms collected at 77 K revealed BET specific surface areas of 1136 and 238 m2 g−1, respectively. Their CO2 and N2O adsorption capacity is assessed at T = 273 and 298 K and p = 1 bar. Ce_TzTz shows the highest gas uptake (7.9 and 9.7 wt% at 298 K and 11.5 and 12.5 wt% at 273 K for CO2 and N2O, respectively). More interestingly, this homo‐linker MOF possesses a higher capacity, thermodynamic affinity [(Qst)CO2 = 18.2 kJ mol−1 vs (Qst)N2O = 25.4 kJ mol−1] and selectivity (IAST SN2O/CO2 = 1.6 at T = 273 K) toward N2O than the mixed‐linker sample. At variance, Ce_TzTz_PyPy shows a slightly higher capacity, thermodinamic affinity [(Qst)CO2 = 29.5 kJ mol−1 vs (Qst)N2O = 26.4 kJ mol−1] and selectivity (IAST SCO2/N2O = 1.4 at T = 298 K) toward CO2. DFT optimizations carried out on the [N2O@Ce_TzTz] and [CO2@Ce_TzTz_PyPy] systems revealed that the primary adsorption sites are the cerium ions of the [Ce6] metallic node for N2O and the thiazole N‐atoms on the TzTz linker for CO2, respectively. [ABSTRACT FROM AUTHOR]

With the growing attention on both environmental and energy issues, the catalytic conversion of CO 2 has gained tremendous interest of researchers. Herein, we report a bimetal CoZn-ZIF derived highly efficient catalyst CoZn-Z for CO 2 methanation. After prereduction before the catalytic test, an inverse ZnO/Co structure with plentiful uniformly dispersed active sites could be formed, and the obtained CoZn-Z catalyst showed high Co dispersion with principally exposed Co (0002) lattice plane. Sufficient active sites, increased basicity and CO adsorption resulted in enhanced CO 2 methanation catalytic activity, and CO 2 conversion of 62.9 %, CH 4 selectivity of 99.2 % with a STY CH4 of 0.21 mol CH4 ·g cat. −1·h−1 were achieved at 300 °C, 2.6 times of monometallic Co-Z and exceeding most of the reported Co-based catalysts. Furthermore, based on in situ FTIR and DFT calculation, the formation of diverse reaction intermediates was studied and different dominant reaction pathways have been proposed for CoZn-Z and Co-Z. This investigation exhibited great potential of MOFs derived catalysts as superior CO 2 methanation catalysts and elucidates the promoting effect of ZnO in Co-based CO 2 methanation catalysts for the first time. [Display omitted] • CoZn-Z catalyst with ZnO/Co reverse structure and plentiful uniformly dispersed active sites was derived from CoZn-ZIF. • CoZn-Z showed a STY CH4 of 0.21 mol CH4 ·g cat. −1·h−1 at 300 °C, 2.6 times that of its monometallic counterpart. • The promoting effect and reaction pathway on ZnO promoted Co-based methanation catalyst were studied for the first time. • ZnO boosted methanation catalytic activity by improving the metal-dispersion, alkalinity and CO adsorption strength. • The introduction of ZnO changed the dominant reaction path of CO 2 methanation over Co-based catalyst. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) are a rising family of compounds consisting of metal ions (nodes) linked with organic ligands (linkers) to form crystalline structures. Among various methods, an accessible and convenient method with household appliances was adopted to produce the HKUST-1, a type of MOF synthesized using copper (II) acetate monohydrate and 1,3,5-benzenetricarboxylic acid. The mechanochemical synthesis method, which involved a solvent-free ball-milling technique, was utilized in this study through a mortar and pestle. After the synthesis of HKUST-1, its adsorption capacity of CO2 was obtained. Then, the HKUST-1 sample was regenerated by heating it in a toaster oven. Finally, the morphology of the synthesized HKUST-1 sample was characterized by scanning electron microscopy (SEM). Our experimental results confirmed that the HKUST-1 with CO2 adsorption capacity could be synthesized through a convenient and mechanochemical method. The significance of this research lies in the potential impact of an accessible and environmentally friendly synthesis method, which requires no solvents and avoids the need for high-energy laboratory equipment. Additionally, the study reveals the promising CO2 adsorption capacity of the mechanochemically synthesized HKUST-1. Despite the observed minimal CO2 adsorption, this study establishes the groundwork for further exploration of low-cost and high-productivity MOF synthesis using the accessible mechanochemical approach. [ABSTRACT FROM AUTHOR]

[Display omitted] The extra CO 2 that has already been released into the atmosphere has to be removed in order to create a carbon–neutral world. Technologies have been created to remove carbon dioxide from wet flue gas or even directly from ambient air; however, these technologies have not been widely deployed yet. New generations of CO 2 sorbents have been produced as a consequence of recent improvements in material assembly and surface chemistry. We summarize recent progress on water-stable and encapsulated metal–organic frameworks (MOFs) for CO 2 capture under a wide range of environmental and operating conditions. In particular, newly developed water-stable MOFs and hydrophobic coating technologies are discussed with insights into their materials discovery and the synergistic effects between different components of these hybrid sorbent systems. The future perspectives and directions of water-stable and encapsulated MOFs are also elucidated for Direct Air Capture of CO 2 and CO 2 capture from wet flue gas. [ABSTRACT FROM AUTHOR]

The increase in the global population has caused an increment in energy demand, and therefore, energy production has to be maximized through various means including the burning of natural gas. However, the purification of natural gas has caused CO2 levels to increase. Hollow fiber membranes offer advantages over other carbon capture technologies mainly due to their large surface-to-volume ratio, smaller footprint, and higher energy efficiency. In this work, hollow fiber mixed matrix membranes (HFMMMs) were fabricated by utilizing cellulose triacetate (CTA) as the polymer and amine-functionalized metal-organic framework (NH2-MIL-125(Ti)) as the filler for CO2 and CH4 gas permeation. CTA and NH2-MIL-125(Ti) are known for exhibiting a high affinity towards CO2. In addition, the utilization of these components as membrane materials for CO2 and CH4 gas permeation is hardly found in the literature. In this work, NH2-MIL-125(Ti)/CTA HFMMMs were spun by varying the air gap ranging from 1 cm to 7 cm. The filler dispersion, crystallinity, and functional groups of the fabricated HFMMMs were examined using EDX mapping, SEM, XRD, and FTIR. From the gas permeation testing, it was found that the NH2-MIL-125(Ti)/CTA HFMMM spun at an air gap of 1 cm demonstrated a CO2/CH4 ideal gas selectivity of 6.87 and a CO2 permeability of 26.46 GPU. [ABSTRACT FROM AUTHOR]

[Display omitted] • N-doping demonstrated a positive effect on the conversions of CH 4 and CO 2. • N-doping promotes the formation of carbon protective layer and inhibits the agglomeration of active metals. • N-doping enhances the CO 2 adsorption capacity of catalyst and inhibits carbon deposition. • The N-Ni/C@ZIF-67 catalyzed DRM process mainly occurs through rapid reactions between intermediates. Dry reforming of methane (DRM) can convert CO 2 into syngas for the production of fuels and chemicals, offering both environmental and energetic benefits. However, its large-scale industrial applications face challenges such as harsh reaction conditions and catalyst deactivation. In this study, metal–organic frameworks (MOFs) derived N-doped Ni-based bifunctional nanomaterials (Ni-Co/NC) were meticulously synthesized to function as microwave absorbers and catalysts. Efficient syngas production was achieved through the microwave-enhanced DRM process over Ni-Co/NC. The results showed that the Ni-Co/NC catalyst significantly increased the conversion of CH 4 (∼93.2 %) and CO 2 (∼94.8 %). By comparing the changes in the surface properties of the catalysts before and after N-doping, it was found that N-doping enhanced the interaction between the carrier and metal particles, improved the specific surface area and surface basicity, and inhibited the aggregation of metal particles, thereby enhancing catalytic activity. The reaction mechanism was investigated using in-situ infrared spectroscopy, revealing that the formation of intermediates such as carbonates, formates, O-H groups was crucial to improving catalytic activity and stability. Compared to conventional catalytic processes, the catalysts prepared in this study demonstrated stronger catalytic activity and stability in the microwave catalytic process. [ABSTRACT FROM AUTHOR]

Through introducing porphyrinic fragments with different lengths and functional groups, the micro-environments of a series of MOFs were tuned. Among them, MOF-525-NO 2 possesses stronger CO 2 affinity, faster photocurrent response, and efficient photogenerated electron-hole separation and transfer, which finally promoted the efficiency for photocatalytic CO 2 reduction. [Display omitted] • Three isomorphic zirconium-based MOFs were synthesized and employed as photocatalysts for CO 2 reduction. • Among them, MOF-525-NO 2 exhibited the highest catalytic activity without any photosensitizer under visible light. • The microenvironments of MOFs were tuned by introducing different porphyrinic units, which improved the catalytic efficiency. Photocatalytic CO 2 reduction to fuels and chemicals is a promising pathway towards carbon resource recovery. Herein, three isomorphic Fe-porphyrinic MOFs, Zr 6 O 4 (OH) 4 (Fe-TCPP) 3 (MOF-525 , Fe-TCPP = iron 5,10,15,20-tetra(4-carboxyphenyl)-porphyrin), Zr 6 O 4 (OH) 4 (Fe-TCPP-NO 2) 3 (MOF-525-NO 2 , Fe-TCPP-NO 2 = iron 5,10,15,20-tetra(2-nitro-4-carboxyphenyl)-porphyrin), and Zr 6 O 4 (OH) 4 (Fe-TCBPP-NO 2) 3 (MOF-526-NO 2 , Fe-TCBPP-NO 2 = iron 5,10,15,20-tetra[4-(4′-carboxyphenyl)-2-nitrophenyl]-porphyrin) were synthesized and employed as photocatalysts for CO 2 reduction. Among them, MOF-525-NO 2 exhibited the highest catalytic activity with CO and H 2 yields of 10.36 and 0.46 mmol·g−1 without any photosensitizer under visible light. Mechanism investigations suggested that the micro-environments of these MOFs were adjusted by introducing porphyrinic fragments with different lengths and functional groups, resulting in stronger CO 2 affinity, faster photocurrent response, and efficient photogenerated electron-hole separation and transfer, which finally promoted the efficiency for photocatalytic CO 2 reduction. [ABSTRACT FROM AUTHOR]

The presence of amino groups in MOF-526-NH 2 played an important role in adjusting the micro-environment and electronic structure, which improved its CO 2 capture and photoreduction performance. Moreover, amino functionalization of MOFs is expected to become a promising strategy for advanced applications. [Display omitted] • The micro-environments of two Zr-MOFs were tuned by introducing amino groups to porphyrin units. • MOF-526-NH 2 exhibited a higher activity than MOF-526-H for CO 2 reduction. • MOF-526-NH 2 showed good stability during the four rounds of CO 2 reduction. Solar-powered photocatalysis offers a sustainable strategy to convert carbon dioxide into valuable fuels, which mitigates the energy crisis and the greenhouse effect. Nevertheless, exploring efficient, selective, stable, and environmentally friendly photocatalysts for CO 2 reduction continues to meet a significant challenge. Herein, two iron-porphyrinic zirconium-based metal–organic frameworks, Zr 6 O 4 (OH) 4 (FeTCBPP) 3 (MOF-526-H) and Zr 6 O 4 (OH) 4 (FeTCBPP-NH 2) 3 (MOF-526-NH 2) were achieved by the integration of the light-harvesting sites and catalytic centers into one phase (FeTCBPP = iron 5,10,15,20-tetra[4-(4′-carboxyphenyl)phenyl]-porphyrin, FeTCBPP-NH 2 = iron 5,10,15,20-tetra[4-(4′-carboxyphenyl)-2-aminophenyl]-porphyrin), which were employed as a couple of models for CO 2 photoreduction. MOF-526-NH 2 exhibited excellent CO 2 reduction with a CO yield of 21.2 mmol·g−1 in the absence of any photosensitizer under visible light, which was 4-fold higher than that of MOF-526-H. Additionally, MOF-526-NH 2 showed no significant reduction in CO production during the four rounds, indicating that MOF-526-NH 2 possessed good stability. The presence of amino groups in MOF-526-NH 2 played an important role in adjusting the micro-environment and electronic structure, which was beneficial to CO 2 enrichment and light absorption, and thus improved CO 2 photoreduction performance. Based on the density functional theory calculations, a possible mechanism of photocatalytic CO 2 reduction over porphyrinic MOFs was proposed. [ABSTRACT FROM AUTHOR]

CO2 separation from raw natural gas can be achieved through the use of the promising membrane-based technology. Polymeric membranes are a known method for separating CO2 but suffer from trade-offs between its permeability and selectivity. Therefore, through the use of mixed matrix membranes (MMMs) which utilizes inorganic or hybrid fillers such as metal-organic frameworks (MOFs) in polymeric matrix, the permeability and selectivity trade-off can be overcome and possibly surpass the Robeson Upper Bounds. In this study, various types of MOFs are explored in terms of its structure and properties such as thermal and chemical stability. Next, the use of amine and non-amine functionalized MOFs in MMMs development are compared in order to investigate the effects of amine functionalization on the membrane gas separation performance for flat sheet and hollow fiber configurations as reported in the literature. Moreover, the gas transport properties and various challenges faced by hollow fiber mixed matrix membranes (HFMMMs) are discussed. In addition, the utilization of amine functionalization MOF for mitigating the challenges faced is included. Finally, the future directions of amine-functionalized MOF HFMMMs are discussed for the fields of CO2 separation. [ABSTRACT FROM AUTHOR]

Cationic azole-based metal-organic frameworks (MOFs) with remarkable stability and unique pore environment have aroused great research interests. Meanwhile, flexible MOFs which can undergo pore-structure changes upon exposure to external stimuli are ideal materials for gas separation. However, introducing flexibility into the framework of cationic azole-based MOFs is rarely reported. Herein, we synthesized two stable isomorphic cationic MOFs (M-btz-as, M = Co, Ni) based on a linear azole ligand. After activated at high temperature under vacuum, M-btz-ht (M = Co, Ni) were obtained and both MOFs exhibited flexible features in which Co-btz is more flexible than Ni-btz. Different solvent-mediated activation methods were employed to explore their effects on structural flexibility and produced MOFs with different phases. Continuous phase transformation of Co-btz-e was verified by powder X-ray diffraction. In addition, these MOF phases possessed different gas separation abilities affected by their flexible frameworks, and Co-btz-ht exhibited the highest CO2/CH4 separation ability. [ABSTRACT FROM AUTHOR]

A series of hexanuclear Rare-Earth MOFs based on Ce (III) and 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, namely Ce-PCN-224, was constructed by linker induce strategy. This highly stable MOF was proved to be an efficient heterogeneous catalyst for the cycloaddition reactions of CO 2 with epoxides. [Display omitted] • Ce-PCN-224 MOF is synthesized composed of hexanuclear Ce (III) clusters and 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (TCPP) linkers. • The structure of Ce-PCN-224 is analyzed using single-crystal X-ray Diffraction (SCXRD). • Linker induce strategy significantly enhance the stability of rare-earth MOFs. • This highly stable MOF is an efficient heterogeneous catalyst for the cycloaddition of CO 2 with epoxides. In this article, we report a series of hexanuclear rare-earth MOFs based on Ce (III) and 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, namely Ce-PCN-224, with a new zln topology through linker induce strategy. Ce-PCN-224 exhibits permanent porosity, high water and thermal stabilities, and the ability to adsorb dye molecules in the aqueous environment. Moreover, after post-metallation with Fe, Co, and Ni, Ce-PCN-224(Fe) and Ce-PCN-224(Co) were proved to be efficient heterogeneous catalysts for the cycloaddition of CO 2 with epoxides, attributed to the combination of multiple Lewis acidic sites. [ABSTRACT FROM AUTHOR]

In this study, a new process to synthesize Calgary framework 20 (CALF-20), a zinc-based metal-organic framework (MOF), in a H 2 O/methanol solution was developed, exhibiting a high CO 2 adsorption capacity. Generally, CALF-20 was synthesized by a solvothermal method, requiring the consumption of considerable thermal energy. On the other hand, the proposed synthetic process required only 6 min to crystallize CALF-20 in a H 2 O/methanol mixed solution at room temperature (298 K) and normal pressure (101.3 kPa). In addition, CALF-20 was obtained in 93.3 % yield using zinc and oxalate sources under an aging time of 120 min. As-synthesized CALF-20 exhibited a Brunauer–Emmett–Teller surface area of 520 m2 g−1, a micropore volume of 0.19 cm3 g−1, a CO 2 uptake of 3.84 mmol g−1 at 298 K, and a P CO 2 of 100 kPa; these values were similar to those obtained for CALF-20 synthesized by the solvothermal method using high thermal energy. Furthermore, CALF-20 was crystallized without washing using H 2 O. The key factor for the crystallization of the CALF-20 structure in this process was the deprotonation of 1,2,4-triazole, which was caused by the acetate anion derived from zinc acetate as the starting metal source. [Display omitted] • Calgary framework 20 (CALF-20) was successfully synthesized in methanol aqueous solution under room temperature and normal pressure. • The fabrication of CALF-20 structure started after 6 min from the beginning of aging process. • Acetic ion derived from zinc acetate played a role in the deprotonation of 1,2,4-triazole. • CALF-20 structure was fabricated without activation process with solvents. • The micropores for gas adsorption were produced due to the Zn-oxalate-1,2,4-triazole three-dimensional networks. [ABSTRACT FROM AUTHOR]

We report a microporous aluminum-based metal-organic framework (MOF), BUT-22 for high methane (CH4), hydrogen (H2), and carbon dioxide (CO2) storage. At 296 K and 80 bar, BUT-22 exhibits a high gravimetric CH4 storage capacity of 530 cm3 (STP)/g (0.379 g/g). BUT-22 also has a high gravimetric H2 storage capacity of 12 wt.% at 100 bar and 77 K. In addition, the CO2 adsorption studies revealed that BUT-22 exhibits a high absolute gravimetric CO2 uptake of 1.7 g/g at 296 K and 40 bar. [ABSTRACT FROM AUTHOR]

• The NiCo-MOF was designed for the relay electrocatalytic oxidation of HMF-to-FDCA. • The prepared Ni 2 Co 1 -MOF exhibits optimum performance for HMF oxidation. • The excellent performance comes from the synergetic relay effects between diatomic sites. • The ultrashort distance between Ni and Co is more conducive to the diffusion of intermediate. The majority of electrocatalytic conversions of biomass-based molecules involve multiple steps utilizing the cascade reactions. As a result, maintaining the consecutive rate of each independent step is vital to improving the efficiency of the reaction. Whereas the single active species cannot entirely satisfy the demand of synchronous rates. Even with the use of bimetallic catalysts, the focus is still on facilitating the rate of the controlling step in the whole reaction. In this study, the NiCo-metal–organic framework (MOF) with diatomic sites was designed for the relay electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The prepared Ni 2 Co 1 -MOF catalyst exhibited 97.3 % FDCA yield, and 90 % faradaic efficiency, and an excellent stability. Incorporating favorable catalytic activities of Ni and Co facilitates the alcohol-to-aldehyde and aldehyde-to-carboxylic acid conversions, respectively, verifying the relay effect with lower energy demand (1.35 V vs. RHE). Moreover, the ultrashort distance between two sites results in the faster diffusion of intermediates, further accelerating the reaction. The industrial simulation experiment using a pilot reaction equipment demonstrates the satisfied demands for industrial applications. This relay electrocatalysis path provides new insight into the rational design of catalysts for facilitating the electrorefining process with muti-step reactions. [ABSTRACT FROM AUTHOR]

Global warming has become a critical concern that affects the whole ecology and affects greenhouses in the environment. Therefore, there is a great need to design and create new materials for capturing gases to reduce their environmental effects. The porous nature of metal-organic frameworks (MOFs) has emerged as promising gas adsorption and separation candidates and helps reduce global warming by capturing harmful gases like CO 2 , N 2 O, CO, etc. In this review, we have discussed a critical idea for MOF gas adsorbents with insights into the development, synthesis, and structural properties. Moreover, the key factors responsible for gas adsorption and hydrophobicity for fluid gas adsorption are discussed. Furthermore, some recent advances regarding MOFs for CO 2 adsorption/separation have been elucidated in detail. In addition, MOF gas capturing properties and the effect of pore size, surface area, faradaic efficiency, and maximum CO 2 uptake are concluded. The study will open a new pathway for researchers to design and develop efficient gas-capturing materials. [Display omitted] • The design, porosity, surface area, and structural properties of metal-organic frameworks (MOFs) are discussed. • MOF applications for carbon dioxide adsorption, storage, and uptaking are discussed. • MOFs computational and machine learning studies for gas adsorption are studied. • Key findings, current challenges, and future direction are discussed. [ABSTRACT FROM AUTHOR]

Efficiently addressing the challenges related to the 6 H+/6e− photoreduction of CO 2 into CH 3 OH is paramount. These challenges primarily arise from severe recombination of photogenerated carriers, reoxidation of CH 3 OH at high temperatures, and catalyst photo corrosion. The current study focuses on developing Zn-BTC MOF and its composites with CaIn 2 S 4 (referred to as ZMCIS) at various concentrations of CaIn 2 S 4 on ZnMOF (ZMCIS1, ZMCIS2, ZMCIS3, ZMCIS4, and ZMCIS5) to achieve a highly efficient and robust photocatalytic CO 2 reduction to CH 3 OH under ambient conditions, utilizing H 2 O 2 as the hydrogen source. Among all the composites, ZMCIS4 demonstrates excellent light absorption properties, efficient charge carrier separation, and CH 3 OH evolution of 49100 µmol/g.cat, with a quantum efficiency of approximately 78.41%. These values are five times higher than those observed with the pristine Zn-MOF counterpart and nine times higher than traditional CO 2 /H 2 O systems. Notably, these improved performances are attributed to the enhancement of nascent hydrogen atoms (H•) produced through the photo-splitting of H 2 O 2 on the ZMCIS surface. The production of H• is confirmed by subjecting H• to the hydrogenation of nitrobenzene and nitrophenol, resulting in the formation of aniline and aminophenol, respectively. This study opens up a new direction for the efficient photoreduction of CO 2 to CH 3 OH. [Display omitted] • A novel photocatalyst heterostructure combining ternary metal sulfide and ZnMOF was successfully created, enhancing light absorption and charge separation. • The resulting ZnMCIS4 nanocomposite showed remarkable efficiency in converting CO 2 to CH 3 OH, surpassing traditional CO 2 /H 2 O systems using H 2 O 2 as the hydrogen source. • The photolysis of H 2 O 2 generated H• radicals, a vital factor in the CH 3 OH production process, confirmed through various control experiments and hydrogenation reactions. [ABSTRACT FROM AUTHOR]

We report a microporous aluminum-based metal-organic framework (MOF), BUT-22 for high methane (CH4), hydrogen (H2), and carbon dioxide (CO2) storage. At 296 K and 80 bar, BUT-22 exhibits a high gravimetric CH4 storage capacity of 530 cm3 (STP)/g (0.379 g/g). BUT-22 also has a high gravimetric H2 storage capacity of 12 wt.% at 100 bar and 77 K. In addition, the CO2 adsorption studies revealed that BUT-22 exhibits a high absolute gravimetric CO2 uptake of 1.7 g/g at 296 K and 40 bar. [ABSTRACT FROM AUTHOR]

We report a new magnesium metal–organic framework (MOF) (CPM‐107) with a special interaction with CO2. CPM‐107 contains Mg2‐acetate chains crosslinked into a 3D net by terephthalate. It has an anionic framework encapsulating ordered extra‐framework cations and solvent molecules. The desolvated form is closed and unresponsive to common gasses, such as N2, H2, and CH4. Yet, with CO2 at 195 K, it abruptly opens and turns into a rigid porous form that is irreversible via desorption. Once opened by CO2, CPM‐107 remains in the stable porous state accessible to additional gas types over multiple cycles or CO2 itself at different temperatures. The porous phase can be re‐locked to return to the initial closed phase via re‐solvation and desolvation. Such peculiar properties of CPM‐107 are apparently linked to a convergence of factors related to both framework and extra‐framework features. The unusual CO2 effect is currently the only available path to porous CPM‐107 which shows efficient C2H2/CO2 separation. [ABSTRACT FROM AUTHOR]

Graphical abstract (Two fluorinated ultra-microporous materials, NbOFFIVE -1-Ni and AlFFIVE -1-Ni with [NbOF 5 ]2− and [AlF 5 ]2− building block acting as inorganic pillars, respectively, result in much different adsorption behavior for CO 2 and C 2+. NbOFFIVE -1-Ni with confined pore space exhibit much higher CO 2 uptake amount at low pressures, by contrast, AlFFIVE -1-Ni with potential open metal sites in pore spaces exhibit relatively larger pore volume, leading to enhanced C 2 H 2 adsorption performance at low pressures and improved C 2 H 2 /C 2 H 4 separation selectivity). Highlights • Stable fluorinated Metal Organic Frameworks with tunable structural properties. • Structural properties of MFFIVE -1-Ni with relation to C 2+ adsorption were unveiled. • Substitution of Nb5+ by Al3+ led to improved separation for C 2 H 2 /C 2 H 4 :1/99 system. • NbOFFIVE -1-Ni shows unprecedented CO 2 /C 2+ selectivity in favor of CO 2. • Substitution of Nb5+ by Al3+ affects the mechanism involved in C 2+ separations. Abstract In this work, the reticular chemistry approach was implemented on a very stable ultra-microporous fluorinated MFFIVE -1-Ni MOFs to unveil the effect of subtle changes of the structure-employment of different fluorinated inorganic block on the adsorption of C 2 H 2 , C 2 H 4 and CO 2. A series of variable temperature single C 2 H 2 , C 2 H 4 and CO 2 adsorption isotherms and mixed gas adsorption column breakthrough experiments for different C 2 H 2 /C 2 H 4 and CO 2 /C 2 H 2 gas pair systems were carried out on the two isoreticular NbOFFIVE -1-Ni and AlFFIVE -1-Ni, containing respectively [NbOF 5 ]2− and [AlF 5 ]2− inorganic building blocks. The introduction of potential open metal site in a very confined pores led to favoring interaction of C 2 H 2 but lowering the interaction with CO 2 , which resulted in enhancement of C 2 H 2 /C 2 H 4 selectivity at low C 2 H 2 concentration but a decrease in CO 2 /C 2+ selectivity. The comparison of the C 2 H 2 /C 2 H 4 and CO 2 /C 2 H 2 separation performances with the structures of the MFFIVE -1-Ni MOFs provides useful information to shed light on the relationship between the structural features of this MOF platform and C 2 H 2 /C 2 H 4 and CO 2 /C 2 H 2 separation properties. This is a critical step in the wanted rational discovery/design of materials with enhanced performances for C 2 H 2 recovery from C 2 H 4 and CO 2 at different concentration and having different level of input energy for recycling. [ABSTRACT FROM AUTHOR]

Cyclization of propargylic alcohols with CO2 is an important reaction in industry, and noble‐metal catalysts are often employed to ensure the high product yields under environmentally friendly conditions. Herein a porous noble‐metal‐free framework 1 with large 1D channels of 1.66 nm diameter was synthesized for this reaction. Compound 1 exhibits excellent acid/base stability, and is even stable in corrosive triethylamine for one month. Catalytic studies indicate that 1 is an effective catalyst for the cyclization of propargylic alcohols and CO2 without any solvents under mild conditions, and the turnover number (TON) can reach to a record value of 14 400. Furthermore, this MOF catalyst also has rarely seen catalytic activity when the biological macromolecule ethisterone was used as a substrate. Mechanistic studies reveal that the synergistic catalytic effect between CuI and InIII plays a key role in the conversion of CO2. Fixed: A porous anionic framework was designed to catalyze carboxylative cyclization of propargylic alcohols with CO2, and the turnover number (TON) can reach to a record value of 14 400 under mild conditions. It represents the first example that noble‐metal‐free MOFs can directly catalyze carboxylative cyclization of propargylic alcohols with CO2. [ABSTRACT FROM AUTHOR]

• Overviews the current research on the fixation of CO 2 to cyclic carbonate by using MOFs-based materials. • Discuss the different strategy for the fixation of CO 2 to cyclic carbonate. • Focused on the various aspects for further designing of MOFs-based materials. The combustion of fossil fuels leads to the significant emission of carbonaceous compounds (e.g. CO 2 , CO), which results in a range of environmental problems (e.g. global warming). Among numerous carbonaceous compounds, although CO 2 is the main culprit causing greenhouse effect, it is also an important carbon resource that can be used as a raw material for the synthesis of other important chemical substances. Among numerous CO 2 activation and conversion processes, CO 2 cycloaddition is an economically efficient transformation method because of its low price of raw materials, no other by-products during the reaction process, and atomic utilization rate of up to 100%, which comply with "green chemistry" and "atom economy". Moreover, the products of cyclic carbonates (e.g. ethylene carbonate, propylene carbonate) play a crucial role in the electric vehicle industry and are widely utilized for their numerous advantages. However, CO 2 is inert and difficult to be activated, so the search for efficient and stable catalysts is crucial for the rapid CO 2 conversion. Metal-organic frameworks (MOFs) have emerged as highly promising materials in the field of CO 2 activation and conversion due to their tremendous potential for development. This review provides a comprehensive analysis of the application of MOFs based catalysts in CO 2 conversion. In addition, this study explores potential techniques for enhancing the catalytic efficiency of novel catalysts based on MOFs while investigating unexplored reactions for CO 2 conversion. Application of metal-organic frameworks (MOFs)-based catalysts for the direct conversion of carbon dioxide (CO 2) to cyclic carbonate. [Display omitted] [ABSTRACT FROM AUTHOR]

Photocatalytic conversion of diluted CO2 into solar fuel is highly appealing yet still in its infancy. Herein, we demonstrate the metal‐node‐dependent performance for photoreduction of diluted CO2 by constructing Ni metal–organic framework (MOF) monolayers (Ni MOLs). In diluted CO2 (10 %), Ni MOLs exhibit a highest apparent quantum yield of 1.96 % with a CO selectivity of 96.8 %, which not only exceeds reported systems in diluted CO2 but also is superior to most catalysts in pure CO2. Whereas isostructural Co MOLs is almost inactive in diluted CO2, indicating the performance is dependent on the metal nodes. Experimental and theoretical investigations show that strong CO2 binding affinity of Ni MOLs is the crucial factor, which stabilizes the Ni‐CO2 adducts and facilitates CO2‐to‐CO conversion. Doctor node: Photocatalytic conversion of diluted CO2 with high efficiency and selectivity can be achieved on Ni metal–organic framework (MOF) monolayers (Ni MOLs). The initial adsorption of CO2 molecules is the critical step and depends on the nature of the metal node. [ABSTRACT FROM AUTHOR]

Abstract: Industrial synthesis is driven by a delicate balance of the value of the product against the cost of production. Catalysts are often employed to ensure product turnover is economically favorable by ensuring energy use is minimized. One method, which is gaining attention, involves cooperative catalytic systems. By inserting a flexible polymer into a metal–organic framework (MOF) host, the advantages of both components work synergistically to create a composite that efficiently fixes carbon dioxide to transform various epoxides into cyclic carbonates. The resulting material retains high yields under mild conditions with full reusability. By quantitatively studying the kinetic rates, the activation energy was calculated, for a physical mixture of the catalyst components to be about 50 % higher than that of the composite. Through the unification of two catalytically active components, a new opportunity opens up for the development of synergistic systems in multiple applications. [ABSTRACT FROM AUTHOR]

Porous coordination polymers, or metal–organic frameworks (MOFs), provide a unique materials platform due to their regular structure that allows for almost unlimited tunability in terms of pore size, shape, dimensionality and chemical functionalisation. The ability of this class of material to act as agents for the selective capture or separation of small molecules has driven much of the research in the field over the past two decades. One of the major driving forces in recent years has been the ability of porous coordination polymers to act as selective hosts for carbon dioxide, with obvious potential environmental implications for successful materials. Efforts to enhance the selectivity for CO 2 over other gases (particularly those present in exhaust flues) have explored chemical functionalisation of the interior pore space using amines, to give materials that to some extent mimic the standard solution-based processing methods of flue gas that are currently employed. This review examines the three major synthetic routes that are used in order to affect this chemical modification of porous frameworks; (i) post-synthetic grafting of amines to coordinatively unsaturated metal sites, (ii) incorporation of ligands that contain terminal amine groups, and (iii) incorporation of ligands that contain amine embedded within the core of the ligand. The relative merits and shortcomings of these different synthetic approaches are discussed alongside examples of the materials generated using each method. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bio-inspired artificial photosynthetic nanoreactor developed for CO 2 photoreduction. • Efficient double heterostructure enhances electron-hole separation. • Two antenna systems promote the utilization of visible light energy. • Macroscopic architecture capture CO 2 and light, diminishing photosensitizer usage. • Tunable hydrophobicity inhibits the side product of H 2 and improves CO selectivity. CO 2 photoreduction is warmly embraced as a promising strategy to attain carbon neutrality, with natural photosynthesis constituting a valuable source of inspiration for catalyst design. Herein, an In 2 O 3 @ZIF-67 artificial photosynthetic nanoreactor was constructed by growing ZIF-67 on the interior and exterior of MIL-68(In)-derived hollow In 2 O 3 prisms via potential nonclassical crystallization pathway(s), forming an efficient double heterostructure with separated reaction centers and prompt electron transfers. With the introduction of [Ru(bpy) 3 ]2+ photosensitizer, the nanoreactor possesses two antennae to harvest visible light. Additionally, the macroscopic architecture permits enhanced light and photosensitizer utilization, while ZIF-67 facilitates the capture of CO 2. Collectively, the developed nanoreactor exhibits a remarkable CO production rate of 33420 µmol g−1h−1 with the diminished quantity of the photosensitizer. Moreover, the hydrophobicity of the nanoreactor is found to suppress the side product of H 2 and elevate CO selectivity to 94%, further demonstrating the superiority of its exquisite design. [ABSTRACT FROM AUTHOR]

A quartzlike metal–organic framework with interesting one dimensional channel has been synthesized. It exhibits considerable acetylene and carbon dioxide uptake of 41.5 and 24.6 cm 3 g −1 , respectively, and relatively high selectivity for separation of C 2 H 2 /C 2 H 4 , C 2 H 2 /CH 4 , CO 2 /CH 4 and CO 2 /N 2 at ambient condition. [ABSTRACT FROM AUTHOR]

Application of metal–organic frameworks (MOFs)-based nanocatalysts for the direct conversion of carbon dioxide (CO 2) to value-added chemicals. [Display omitted] This review discusses the real-world application of metal–organic frameworks (MOFs)-based nanocatalysts for direct conversion of carbon dioxide (CO 2) to value-added chemicals. Since CO 2 emission levels have been incessantly on the upsurge, the conversion of CO 2 to value-added chemical products like methane, methanol, ethanol, olefins, heterocycles, oligomers, etc. is gaining significant prominence. Metal-Organic Frameworks (MOFs) owing to their characteristic features like tunable porosity, structural uniformity, and higher internal surface area are known to accelerate several reactions of high interest that even surpass the shortcomings associated with homogeneous catalysts. Herein, the recent trends and advancements for CO 2 conversion to value-added products are comprehensively deliberated that exploit the specific MOFs-based nanocatalysts for the conversion of CO 2 using different methods like photocatalysis, electrocatalysis, photoelectrocatalysis, hydrogenation, the cycloaddition of epoxides with CO 2 , and carboxylation of terminal alkynes with CO 2. In addition, special emphasis is given to the relationship between CO 2 capture capacity and catalytic activity of the MOFs-based nanocomposites developed in recent years (2015–2022). The entire compendium of literature chronicles their exceptional competence in the conversion of CO 2 , making these nanocomposites promising candidates for real-world applications. Furthermore, the merits, demerits, and prospects of MOFs-based nanocatalysts have been elaborated, by accentuating their future outlooks in this emerging and topical research field. [ABSTRACT FROM AUTHOR]

A novel microporous metal-organic framework dptz-CuGeF 6 was synthesized at room temperature and exhibited excellent performance for separation of CO 2 , CH 4 and N 2. [Display omitted] • A new MOF dptz-CuGeF 6 with ultra-microporous structure was synthesized at room temperature. • dptz-CuGeF 6 showed good stability against water vapor and some organic solvents. • Its CO 2 capacity at 15 kPa and 100 kPa reached as high as 2.17 mmol/g and 3.23 mmol/g at 298 K separately. • Its CO 2 /CH 4 and CO 2 /N 2 selectivity reached as high as 80 and 175.5, respectively. • Molecule simulation revealed that the fluorine groups are mainly responsible for its high selectivity of CO 2. Efficient capture of CO 2 from flue gas and removal of CO 2 from biomethane by physical adsorption are in great need. Herein, we report the facile synthesis of a new pillared-layer metal-organic frameworks, dptz-CuGeF 6 for CO 2 separation from the flue gas or the biomethane. The resulting samples were characterized. Structurally, the dptz-CuGeF 6 possess double-interpenetrated frameworks formed by two staggered, independent sql sheets, in which the cations Cu2+ are coordinated by four dptz ligands, making the dptz-CuGeF 6 exhibit narrow and uniform ultra-micropores of 5.25 Å. Its CO 2 capacity reached 2.17 mmol/g at 15 kPa and 3.23 mmol/g at 100 kPa separately, and its selectivity of CO 2 /CH 4 (50:50) and CO 2 /N 2 (15:85) reached as high as 80 and 175.5, respectively. The stability experiments demonstrated the intact structure of dptz-CuGeF 6 was retained after exposure in moisture air (RH = 50% or RH = 80%) as well as in several polar solvents. Breakthrough experiments confirmed that CO 2 /CH 4 or CO 2 /N 2 binary mixture were efficiently separated. Molecule simulation revealed that both F···C CO2 and multiple C-H···O CO2 interactions in the pores of dptz-CuGeF 6 played an important role in enhancing its selectivity of CO 2 adsorption. The dptz-CuGeF 6 would be promising for CO 2 capture and separation from flue gas or biomethane. [ABSTRACT FROM AUTHOR]

[Display omitted] • MOF-801-FA were synthesised via utilizing a mixed-ligand strategy. • Gas adsorption was boosted, e.g., a 2.5-fold increase for methane capture. • Prominent IAST selectivities were witnessed for CH 4 /N 2 and CO 2 /N 2 mixture. • MOF-801-FA reveal clean and sharp separations in a high relative humidity. The capture of carbon and hydrocarbons is significant to the utilization of valuable resources and the mitigation of global warming, but achieving high gas capacity and selectivity at the same time remains a challenge, especially in the presence of high humidity. In this regard, based on the building block of MOF-801, MOF-801-FA structures were synthesized with high quality and few defects through a mixed-ligand strategy, in which formate ligands were introduced into the framework apart from fumarate ligands. This brought about tremendous increases in gas adsorption capacity, e.g., ca. 2.5-fold and 1.1-fold enhancement occurred to the adsorption of CH 4 and CO 2 in MOF-801-Hf-FA than MOF-801-Hf at 298 K and 1 bar. Besides, prominent IAST selectivities were also witnessed in MOF-801-FA, higher than those in the pristine MOFs, for CH 4 /N 2 and CO 2 /N 2 mixtures under ambient conditions. We then confirmed the efficient performance of MOF-801-FA for real CH 4 /N 2 and CO 2 /N 2 mixtures using the breakthrough experiments and following cycling tests, even in a relative humidity of 90%. Thus, the mixed-linker strategy was demonstrated effective to tune the structures of MOFs, and boost their performance in gas adsorption and separation. The results also showed that, with high capacities for CH 4 and CO 2 , superior selectivities over N 2 , desirable water resistance and facile regeneration, MOF-801-M−FA (M = Zr or Hf) are promising candidates for capturing CH 4 and CO 2 from N 2 in industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • The C 2 H 2 /CO 2 separation for fluorinated and nonfluorinated MOFs is presented. • JXNU-12(F) exhibits significantly enhanced C 2 H 2 /CO 2 separation than that of JXNU-12. • JXNU-12(F) dispalys aprominent C 2 H 2 -captured amount in the breakthrough experiments. • Fluorination exerts a pronounced impact on C 2 H 2 uptake and C 2 H 2 /CO 2 selectivity. • The pores induced by pore partition and fluorination are optimized for trapping C 2 H 2. Inspired by the unique properties of fluorous compounds, the deliberate replacement of H atoms with F atoms in organic linkers of metal–organic frameworks (MOFs) could be of highly interesting. Herein we rationally developed a fluorinated MOF of JXNU-12(F) derived from the parent MOF of JXNU-12 in the presence of the pore partition agent. Remarkably, H/F substitution maintains the crystal structures of MOFs but dramatically enhances the C 2 H 2 /CO 2 separation properties. The C 2 H 2 uptake of JXNU-12(F) (298 K and 1 bar) is 1.48 times higher than that of JXNU-12 even though the pore volume of JXNU-12(F) is 84% of JXNU-12. Whereas both MOFs exhibit the same CO 2 uptakes under the same conditions. The C 2 H 2 /CO 2 adsorption selectivity of JXNU-12(F) at 1 bar and 298 K is 2 times that of JXNU-12, emphasizing the importance of fluorine substitution. An excellent C 2 H 2 /CO 2 separation with a large C 2 H 2 captured amount of 4.7 mmol g−1 was achieved with JXNU-12(F), ranking among the best-performing MOFs. The significant performance enhancement in JXNU-12(F) is rationalized by the large electronegativity and polarizability of fluorine groups exposed on the pore surfaces and the well-matched pore spaces generated by pore partition for trapping C 2 H 2 , which collaboratively enhance framework-C 2 H 2 interactions as revealed by computional simulations. [ABSTRACT FROM AUTHOR]

• CO 2 uptake in MOFs was modeled using MLP-LMA, MLP-BR, ELM, and GP. • The proposed models demonstrated accurate prediction performance. • The MLP-LMA outperformed both of the other ML models and the existing paradigms. The emission of greenhouse gases such as carbon dioxide (CO 2) is considered the most acute issue of the 21st century around the globe. Due to this fact, significant efforts have been made to develop rigorous techniques for reducing the amount of CO 2 in the atmosphere. Adsorption of CO 2 in metal–organic frameworks (MOFs) is one of the efficient technologies for mitigating the high levels of emitted CO 2. The main aim of this study is to examine the aptitudes of four advanced intelligent models, including multilayer perceptron (MLP) optimized with Levenberg-Marquardt (MLP-LMA) and Bayesian Regularization (MLP-BR), extreme learning machine (ELM), and genetic programming (GP) in predicting CO 2 uptake in MOFs. A sufficiently widespread source of data was used from literature, including more than 500 measurements of CO 2 uptake in13 MOFs with various pressures at two temperature values. The results showed that the implemented intelligent paradigms provide accurate estimations of CO 2 uptake in MOFs. Besides, error analyses and comparison of the prediction performance revealed that the MLP-LMA model outperformed the other intelligent models and the prior paradigms in the literature. Moreover, the MLP-LMA model yielded an overall coefficient of determination (R2) of 0.9998 and average absolute relative deviation (AARD) of 0.9205%. Finally, the trend analysis confirmed the high integrity of the MLP-LMA model in prognosticating CO 2 uptake in MOFs, and its predictions overlapped perfectly the measured values with changes in pressure and temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bromide-based ILs, [PMIM][Br] and [BMIM][Br], were incorporated in MOF MIL-101(Cr). • MIL-101(Cr) and IL@MIL-101(Cr) composites gas adsorption performance was assessed. • MMMs with MIL-101(Cr) and the two IL@MIL-101(Cr) were developed and characterized. • The presence of IL in MIL-101(Cr) structure improved the MMMs mechanical properties. • IL@MOF composites can have an impact on the MMMs gas separation performance. New composite materials made of bromide-based ionic liquids (ILs) and metal–organic framework (MOF) MIL-101(Cr) were produced using two different ILs. The powdered composites [PMIM][Br]@MIL-101(Cr) and [BMIM][Br]@MIL-101(Cr) were rigorously characterized, and it was confirmed that both ILs were incorporated into the MOF structure. Single-component CO 2 and N 2 adsorption–desorption isotherms for the pristine MIL-101(Cr) and [BMIM][Br]@MIL-101(Cr), at 303 K and up to 10 bar, showed that the composite has lower gas adsorption capacity and selectivity when compared with the pristine MOF due to the IL incorporation. Mixed Matrix membranes (MMMs) were prepared by the solvent evaporation method, using Matrimid®5218 as the polymeric matrix, and MIL-101(Cr) and IL@MIL-101(Cr) composites as fillers with different loadings (10, 20 and 30 wt%). All prepared membranes were dense, except for the Matrimid®5218/[PMIM][Br]@MIL-101(Cr) ones, and their mechanical properties were improved by the presence of the IL in the composite fillers. Single-gas permeation experiments with CO 2 and N 2 were performed at 303 K for the Matrimid®5218/MIL-101(Cr) and Matrimid®5218/[BMIM][Br]@MIL-101(Cr) membranes, as the Matrimid®5218/[PMIM][Br]@MIL-101(Cr) showed voids. Independently of the filler percentage, the Matrimid®5218/MIL-101(Cr) membranes showed superior CO 2 permeability than the Matrimid®5218/[BMIM][Br]@MIL-101(Cr) ones. In every case, the best CO 2 /N 2 selectivity was achieved with a 20 wt% of filler loading, which indicates the existence of an optimum loading that yields the best membrane separation performance. [ABSTRACT FROM AUTHOR]

Polyoxometalates (POMs) ions are ideal building blocks to construct cluster-based MOFs with excellent catalytic properties. However, the syntheses of POM-based MOFs with the employment of azolate ligands is quite challenging because of the incompatibility of the formation of POMs and metal-azolate. In this work, by finely tune pH value of the reaction system, one POM-based MOFs has been successfully obtained. Induced by structure-directing ligand, a new series of polyoxometalate-based Cu(II)-pyrazolate photocatalytic compounds with crystal structures varying from 1D to 3D have synthesized, which are efficient photocatalysts for CO 2 absorption. [Display omitted] • The structure of POM-based MOF can be selectively controlled by varying the pH value. • A polyoxometalate-based Cu(II)-pyrazolate was prepared with good performance for CO2 absorption/desorption. • The CO2 absorption/desorption activity was attributed to the effect of 3D MOF. [ABSTRACT FROM AUTHOR]

[Display omitted] • The level of atmospheric carbon dioxide is at the global alarming stage. • Metal-Organic Frameworks (MOFs) have exhibited appealing features suitable for application in the CO 2 capture and conversion. • Methanol, methanoic acid, syngas, hydrocarbons, etc., are the main products of CO 2 conversion. • The photochemical (photocatalytic) conversion has shown features that bettered the other methods of conversions. Carbon dioxide (CO 2) has become a primary atmospheric greenhouse gas that has stirred up numerous energies and environmental-related mishaps around the world. Its unwelcome contribution to the decay of the global ecosystem has generated alarming concerns. Therefore, it has triggered an urgent need to design reliable methods for capturing and converting atmospheric CO 2 into valuable chemical products and/or feedstocks. It is expected that these valuable chemical products will enhance significantly, the stability of the ecosystem and promote sustainable development of the energy sector. A few years back, metal-organic frameworks (MOFs) materials have displayed magnificent heterogeneous catalytic behavior owing to their appealing chemical features and high internal surface area. Because of the captivating properties possessed by these MOFs and their ease of synthesis, experimental tests to ascertain structure-function relationships for CO 2 conversion into some value-added chemical products became lucrative. Therefore, in this review, recent developments, and the participation of MOFs as reliable catalysts for capturing and converting CO 2 into valuable chemical products are critically reviewed. Finally, limitations and prospects of MOFs as heterogeneous catalysts for the capture and conversion of CO 2 , are addressed as well. [ABSTRACT FROM AUTHOR]

• Abundant Co/MnO heterointerfaces are engineered in porous graphitic carbon (PGC). • The resulted Co/MnO@PGC catalyst showed excellent catalytic performance during the low temperature CO 2 methanation. • In situ generated Co/MnO heterointerfaces promote CO 2 adsorption and facilitate CO 2 activation. • A synergy between Co0 and MnO at the Co/MnO heterointerface is responsible for the superior performance of Co/MnO@PGC. Direct conversion of CO 2 into CH 4 provides an eco-friendly way of mitigating CO 2 emissions and reducing the demand for fossil fuels, but this process was kinetically hindered under low temperature because of the high stability of CO 2 molecule. The search for efficient low-cost catalysts capable of converting CO 2 into CH 4 with a high space-time yield (STY CH4) at low temperature is becoming more desirable. Here we report a highly efficient, stable and core-shell catalyst with abundant Co/MnO heterointerface inside porous graphitic carbon (Co/MnO@PGC), which can be easily obtained by one-step calcination of a bimetal-organic framework (CoMn-MOF-74). The combination of various the nanoscale characterizations and theoretical modeling ascertain that the in situ generated Co/MnO heterostructured nanoparticles (NPs) not only create many metal defects and oxygen vacancies, but also enhance the Co-MnO interaction at Co/MnO heterointerface, which promote CO 2 adsorption and facilitate CO 2 activation. The resulting Co/MnO@PGC is able to convert CO 2 to CH 4 at temperature even as low as 160 °C with >99% selectivity and exceptional high STY CH4 of 0.14 μmol CH4 ·s−1·g cat. −1, surpassing by far the most active Co catalysts reported up to now under the identical condition. Most astonishingly, at a higher pressure (30 bar), the STY CH4 can reach up to 5.60 μmol CH4 ·s−1·g cat. −1 at 160 °C, which is comparable to the optimal level of Ru-based catalyst, and simultaneously sets a new benchmark for the Co-based methanation catalyst. On the basis of catalytic studies and in situ FTIR spectroscopy of CO 2 methanation experiments, the active sites responsible for this superior performance for Co/MnO@PGC can be associated with a synergy between Co° and MnO at the Co/MnO heterointerface, where H 2 is efficiently dissociated on the Co° and the strong adsorption and activation of CO 2 taking place on the adjacent MnO. This work provides a promising way for the design of advanced CO 2 methanation catalysts. [ABSTRACT FROM AUTHOR]

• The Metal-Organic Frameworks (MOF) were investigated as potential adsorbents. • Two main adsorptive process namely, CO 2 capture and CH 4 storage via MOF adsorbents have been reviewed. • The adsorptive separation mechanism have been investigated and some recent works in this area were highlighted. Due to their high pore volume and high porosity, Metal-Organic Frameworks (MOFs), containing one-, two-, and three-dimensional structures, have been developing at an accelerating rate, especially for the adsorption studies. Herein, the adsorption separation mechanisms are being investigated. An adsorption-based separation can be governed by the size exclusion, through the difference in affinity, and separation by the difference in the adsorption rate. As the high potential of MOFs in the field of separation is visible, one must gain an understanding of the underlying process, under which, the separation occurs. Moreover, recent advancements of MOFs' chemistry were studied, in addition to the structural characteristics of MOFs. The synthesis technique is also an integral part of exploiting MOFs for separation purposes. Thus, a brief review of the novel approaches used for MOFs synthesis has been carried out. Since the aim of this review is divulging the adsorption-based separation, two of the most significant applications of MOFs namely carbon-dioxide capture and methane storage were explored. [ABSTRACT FROM AUTHOR]

• CO 2 recycling via its electrocatalytic conversion into valuable products is a hot topic. • A plethora of diverse precursors (MOFs, biomass, polymers, etc.) is available to produce carbon electrocatalysts for CO2RR. • Carbonization is a very versatile tool to modulate the final structural and electrocatalytic properties of CO2RR catalysts. • Important efforts are required to improve catalysts selectivity toward the valuable C2+ products: ethanol, ethylene, etc. The recycling of carbon dioxide via its electroreduction (CO 2 RR) is a key factor to stimulate the capture of this greenhouse gas, being a promising green strategy for achieving sustainable development. Nanostructured carbon materials play a protagonist role in the search of efficient and selective CO 2 RR electrocatalysts and, at the same time, pyrolysis is one of the most versatile tools to produce tailored nanocarbons. Nanocarbons involving a variety of dopants, metal single-atom sites/nanoparticles and textural/structural arrangements can be obtained through rational precursor/s selection and control of the carbonization conditions. Thus, this review aims to highlight the advances in CO 2 RR electrocatalysis using nanocarbons derived from MOFs, biomass, polymers, and other precursors, assessing the aspects to improve as well. Bearing in mind that selectivity toward valuable products is the ever-present obstacle, we summarize the nature and proportion of the produced compounds. With this, we provide a useful guide in which carbon synthetic conditions, structural features and electrocatalytic metrics are correlated to facilitate further progress in this boisterous field. After all, the main limitations detected in CO 2 RR research as well as potential approaches to address them are included. [ABSTRACT FROM AUTHOR]

• The metal-organic frameworks (MOFs) are proving to be effective materials for CO 2 capture and conversion. • Stability of MOFs and adsorption mechanisms of CO 2 capture in MOFs have been reviewed. • Various approaches for enhancing the adsorption capacity and efficacy of MOFs are discussed. • MOFs add functionality in mixed-matrix membranes (MMMs) as fillers for boosting the separation efficiency of MMMs. The emissions of carbon dioxide (CO 2) and other greenhouse gases from rapidly growing industries and households are of great concern. These emissions cause problems like global warming and climate change. Although various technologies can be used to decline the alarming levels of greenhouse gases, CO 2 capturing is deemed more cost-effective. The metal-organic frameworks (MOFs) are proving to be effective adsorbent material for CO 2 capture due to their microporous structure. MOFs exhibit varying extents of chemical and thermal stabilities; hence, distinct MOFs can be selected for applications based on the working environment. In this article, thermal, chemical, mechanical, and hydrothermal stabilities of MOFs and adsorption mechanisms of CO 2 capture in MOFs were overviewed. Also, the approaches for enhancing the adsorption capacity and efficacy of MOFs were discussed. Moreover, the utilization of MOFs to improve the separation efficacy of mixed matrix membranes (MMMs) is also discussed. Furthermore, as the conversion of CO 2 to fuels and other useful products is a viable next step to CO 2 capture, therefore, recent progress in the utilization of MOFs as catalysts for CO 2 conversion was also briefly discussed. Present work attempts to link the chemistry of MOFs to process economics for post-combustion CO 2 capture. [ABSTRACT FROM AUTHOR]

• A new metal-organic framework UTSA-83 has been developed for the challenging C 2 H 2 /CO 2 separation. • Crystallographic analysis reveals UTSA-83 features unique square grid-like coordination layers. • UTSA-83 exhibits highly selective adsorption of C 2 H 2 /CO 2 separation under ambient condition. A new two-dimensional (2D) microporous metal-organic framework, [Cu(BDC-2Br)(H 2 O)]·DMF (UTSA-83, DMF = N , N '-dimethylformamide), has been synthesized by solvothermal reaction of 4,6-dibromoisophthalic acid (H 2 BDC-2Br) and Cu(NO 3) 2 ·2.5H 2 O. Single-crystal X-ray crystallographic study reveals that the Cu(II) atoms in UTSA-83 are linked by BDC-2Br ligands to form square grid-like (sql) layers, further stacking together via multiple hydrogen bonding interactions. The removal of DMF molecules allows UTSA-83a to exhibit permanent porosity. Gas sorption measurements of UTSA-83 exhibited selective acetylene (C 2 H 2) adsorption over carbon dioxide (CO 2) with a C 2 H 2 /CO 2 uptake ratio of about 3.1 at 298 K and 1 atm, giving a C 2 H 2 /CO 2 selectivity of 6.2. [ABSTRACT FROM AUTHOR]

The efficient reduction of CO2 into valuable products such as methanol, over metal-organic frameworks (MOFs) based catalyst, has received much attention. The photocatalytic reduction is considered the most economical method due to the utilization of solar energy. In this study, Copper (II)/Zeolitic Imidazolate Framework-8 (Cu/ZIF-8) catalysts were synthesized via a hydrothermal method for photocatalytic reduction of CO2 to methanol. The synthesized catalysts were characterized by X-ray Photoelectron Spectroscopy (XPS), Field Emission Scanning Electron Microscopy (FESEM) coupled with Energy Dispersive X-ray (EDX), Ultraviolet-visible (UV-vis) spectroscopy, and X-Ray Diffraction (XRD). The host ZIF-8, treated with 2 mmol copper prepared in 2M ammonium hydroxide solution showed the highest photocatalytic activity. The crystal structures of ZIF-8 and 2Cu/ZIF-8N2 catalysts were observed as cubic and orthorhombic, respectively and the XPS analysis confirmed the deposition of Cu (II) ions over ZIF-8 surface among all the prepared catalysts. The orthorhombic structure, nano-sized crystals, morphology and Cu loading of the 2Cu/ZIF-8N2 catalyst were the core factors to influence the photocatalytic activity. The yield of Methanol was found to be 35.82 µmol/L·g after 6 h of irradiations on 2Cu/ZIF-8N2 catalyst in the wavelength range between 530–580 nm. The copper-based ZIF-8 catalyst has proven as an alternative approach for the economical photocatalytic reduction of CO2 to CH3OH. [ABSTRACT FROM AUTHOR]