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Zeolitic imidazolate frameworks (ZIFs) hold great potential for carbon capture, while a major challenge for the practical application of ZIFs is the development of convenient three-dimensional bulk materials. Here, sustainable and biodegradable bacterial cellulose (BC) was used as the substrate for ZIF growth. Amino-functionalized ZIF-8 (ZIF-8-NH 2 ) was prepared within BC substrate via an in situ growth approach. ZIF crystals were wrapped uniformly over cellulose fibers and the chelating effect between metal (zinc) ions and hydroxyl groups makes the composites have high interface affinity and compatibility. The resulting foams presented a high CO 2 adsorption capacity of 1.63 mmol/g (25 °C, 1 bar). Moreover, ZIF-8-NH 2 @BC foams are facile to be regenerated by heating at 80 °C. This work provides a new avenue to construct ZIF/cellulose composites for gas treatment applications., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The effective utilization of biomass resources can bring significantly environmental and economic benefits. In this context, tea saponin, which can be easily and extensively extracted from the oil cake as the biomass waste during the seed oil production from camellia seeds, is explored as the precursor to synthesize porous carbon bearing abundant –OH and –COOH groups via a simple carbonization process. Owing to the obtained porous structure and existence of rich oxygen-containing groups serving as Lewis acidic sites, the carbonized tea saponin (CTS) can display impressive catalytic activities for CO 2 cycloaddition reaction with both high selectivity (> 99%) and high yield of target cyclic carbonate under either thermally driven (80 °C and 0.1 MPa CO 2) or photo-thermally driven (UV-Vis light irradiation with the light intensity of 350 mW/cm2) conditions. In addition, benefiting from the good chemical stability, CTS can be reused for many cycles with almost no catalytic activity loss, making CTS a promising biomass-based catalyst for CO 2 fixation under mild conditions. [Display omitted] • Tea saponin-derived carbon (CTS) with rich –OH and –COOH groups was obtained. • CTS displays impressive catalytic activities for CO 2 cycloaddition. • CTS can drive CO 2 cycloaddition reaction thermally and photothermally. [ABSTRACT FROM AUTHOR]

Imidazole ionic liquids were encapsulated in the cavities of a metal–organic framework (MOF), via ship-in-bottle and post-synthetic polymerization strategies to afford IL@MIL-101 and polyILs@MIL-101, respectively. It is found that the catalyst with high mobility has better performance of carbon dioxide conversion. [ABSTRACT FROM AUTHOR]

Chemical carbon dioxide (CO 2) fixation over heterogenous catalysts under more realistic conditions enables the acceleration of the global carbon cycle. Despite the recent advances, many catalysts often suffer from chemical lability, mass transfer resistance, as well as single catalytic species. To this end, this work demonstrates a metal-organic framework (MOF)-templated thermolysis to give bimetallic oxides, Cu x Zn y -BMOs, featuring hierarchically porous structures. By varying the initial molar ratio of Cu/Zn, the local coordination environment can be adjusted, thus regulating the type and quantity of active species. Together with its abundant active sites and appropriate pore size, the optimized Cu 1 Zn 2 -BMO not only achieves a high activity (98% yield) for the coupling of CO 2 and epichlorohydrin under solvent-free mild conditions, but also promotes the N-formylation of CO 2 with amines. Worthy to note, the decent chemical stability endows Cu 1 Zn 2 -BMO with almost unchanged performance even after long exposure to humidity. Our study offers a reliable strategy for the structure regulation of catalysts to enhance practical CO 2 catalytic conversion. [Display omitted] • Synthesis of hierarchically porous bimetallic oxides by a MOF-templated process. • Surface active species can be adjusted by varying the initial molar ratio of Cu/Zn. • Cu 1 Zn 2 -BMO shows high activity for CO 2 cycloaddition and N-formylation of CO 2 with amines. • High yield can be maintained even after a long-time moisture exposure. [ABSTRACT FROM AUTHOR]

The synergistic catalysis involving multiple active sites provides a promising method for improved catalytic activity. In this work, we developed a gentle acetic acid-assisted polyhydroxy acid modification strategy to regulate the coordination environment of a zirconium-based MOF, UiO-66. D -gluconic acid with multiple hydroxyl groups is selected to replace the acetic acid coordinated at the metal nodes of UiO-66 via competitive coordination, allowing for the coexistence of hydrogen bonding donors and Lewis acid sites. The effect of acetic acid and D -gluconic acid separately as modulator and modifier agent to produce linker defects on catalytic properties of UiO-66 was investigated in the cycloaddition of carbon dioxide (CO 2) with epichlorohydrin. It was demonstrated that the activity of UiO-66 can be tuned by the amount of D -gluconic acid. Remarkably, the resultant UiO-66-GA-1200, which is modified with 1200 μL of D -gluconic acid, achieves a high catalytic yield for CO 2 cycloaddition of epichlorohydrin under 1 bar CO 2 and 60 °C. In contrast of pure UiO-66, UiO-66-GA-1200 shows admirable catalytic activities (92–94% yield) even after exposure to humid environment or in simulated flue gas. This work provides a novel method for constructing MOF-based solid acid catalysts and casts a new light on the development of practical CO 2 utilization. [Display omitted] • A series of zirconium-based MOFs containing multiple hydroxyl groups were prepared. • UiO-66-GA-1200 has good catalytic activity for CO 2 cycloaddition reaction. • UiO-66-GA-1200 can be facilely separated by external magnetic field and reused. • The catalytic activity can be well maintained under simulated flue gas conditions. [ABSTRACT FROM AUTHOR]

Integrating dual Lewis acid and base as well as rational hierarchical pore structure in one catalyst is favorable to significantly boost the CO 2 cycloaddition reaction at mild conditions. In this regard, carbonized melamine sponge (CMS) featuring a highly porous network, rich nitrogen doping and excellent photothermal capability is employed as the ideal host for the construction of CMS@MOFs (namely, MIL-88-NH 2 and ZIF-8-NH 2) composites with diverse acid-base properties. Results show that all the obtained composites exhibited a satisfactory CO 2 adsorbing capacity (33–54 cm3/g) and delivered a remarkable yield of target cyclic carbonate at either mild thermal conditions (0.1 MPa CO 2 and 80 oC) or under light irradiation (light intensity: ~350 mW/cm2) at room temperature. Even with diluted CO 2 (15 vol. % CO 2), high yields of 80–82 % are achievable. Moreover, the used catalysts can be easily recycled from reaction systems, leading to a good recyclability. [Display omitted] • Carbonized melamine sponge (CMS)@MOFs composites are developed. • The obtained catalysts have dual Lewis acid and base and hierarchical pores. • The obtained catalysts display good performance for CO 2 cycloaddition. [ABSTRACT FROM AUTHOR]

This paper reports a phase inversion method for the preparation of macroporous polysulfone (PS) composite spheres through a single orifice spinneret. Surfactant F127 was pre-added in the polymer solution as a surface pore-forming agent, and different amount of zeolitic imidazolate framework-8 (ZIF-8) particles were incorporated to form the ZIF-8/polysulfone (ZIF-8/PS)-composite spheres. ZIF-8 and polymer acted as the adsorbent and binder in the final composite spheres, respectively. The fabrication conditions, such as the types of the surfactant, the amount of the surfactant, and ZIF-8 added in the polymer solution, were investigated. Nitrogen and carbon dioxide sorption analysis indicated the ZIF-8/PS composite spheres had similar properties as the pure ZIF-8 particles, and the active sites of ZIF-8 in the polymer composites were well exposed. The composite spheres exhibited advantages of easy handling and recycling over ZIF-8 particles, and this phase inversion method can be extended to prepare other polymer composite spheres. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zn x Fe y -ZIF/MXene catalysts have been fabricated by an in situ growth method. • MXene acts as a light harvester to extend the light absorption of bimetallic ZIF. • A high yield (96%) is obtained by Zn20Fe1-ZIF/MXene for solar driven CO2 fixation. • The catalytic activity can be maintained under simulated flue gas conditions. • photo-induced photo-thermal catalytic mechanism has been investigated. Photodriven CO 2 conversion has been widely recognized as an effective pathway for achieving carbon neutrality. In this paper, we demonstrate the immobilization of bimetallic Zn/Fe ZIF onto the surface of Ti 3 C 2 T x MXene via an in situ growth process for photodriven solvent-free CO 2 cycloaddition. MXene can extend the optical response of bimetallic ZIF into the near-infrared region. In turn, the incorporated MOF particles effectively prevent the layers of MXene from stacking. The resulting Zn 20 Fe 1 -ZIF/MXene has improved activity (96% yield) in the cycloaddition of epichlorohydrin with 1 bar CO 2 under full spectrum illumination (350 mW/cm2) for 6 h, ca. 3.4, 1.7, and 1.2 times higher than those of pure Zn 20 Fe 1 -ZIF, MXene, and the physical mixture, respectively. Besides, this hybrid catalyst provides desirable stability and performance even after several catalytic cycles, exposure to humid environment or under diluted CO 2 (15%). Control experiments and infrared thermography reveal the synergistic photocatalytic-photothermal contribution of hybrid materials to the photoinduced CO 2 fixation. Our research offers a facile method to construct MOF containing photocatalysts for application of CO 2 conversion with high practical utility. [ABSTRACT FROM AUTHOR]

In this work, Amine-functionalized CNF/UiO-66 (CNF–NH 2 /UiO-66) composite membranes were fabricated by incorporating UiO-66 nanoparticles in the CNF–NH 2 matrix. The CO 2 -facilitated transfer channels can be constructed in the CNF–NH 2 /UiO-66 composite membrane. As a natural polymer material, CNF–NH 2 would absorb water and form a gel-like structure under humidification. The adsorbed water can convert CO 2 into bicarbonate ions (HCO 3 −) through the catalysis of amino groups on CNF–NH 2. Moreover, in CNF–NH 2 /UiO-66 composite membranes, HCO 3 − could quickly migrate to the permeate side promoted by the porous UiO-66, facilitating CO 2 transport. The optimum membrane gave a CO 2 permeability of 257.0 Barrer with a CO 2 /CH 4 ideal selectivity of 71.3. [Display omitted] • Hydrogel material CNF–NH 2 was selected as membrane matrix for gas separation. • Adsorbed water molecules can act as fast moving carriers of CO 2. • Porous UiO-66 was incorporated in CNF–NH 2 matrix as a highway for CO 2 transport. • Significantly higher CO 2 permeability was observed for membranes in a humid state. [ABSTRACT FROM AUTHOR]

• Mixed matrix membranes comprised of MXenes and nanocellulose were fabricated. • Incorporation of MXene nanosheets provided the membranes with gas transfer channels. • The hydrogen bonds boosted the interfacial affinity between MXenes and cellulose. • The intercalation of nanocellulose can enlarge the interlayer spacing of MXenes. • The optimal MMMs present CO 2 /N 2 and CO 2 /CH 4 ideal selectivities of 42.6 and 47.8. To achieve high capability mixed matrix membranes for CO 2 separation, it is vital to construct the suitable transport channels to enhance the diffusivity-enabled selectivity as well as an excellent affinity toward target gas molecules to increase the solubility-based selectivity. Herein, composite membranes were constructed by integrating two-dimensional MXene nanosheets into a carboxylated nanocellulose matrix. The carboxyl-rich cellulose interacts with the surface groups of MXene, which contributes to a superior interface compatibility and repairs the non-selective voids. In particular, one-dimensional nanocellulose can intercalate into MXene laminates to regulate the interlayer spacing and suppress the re-stacking of MXenes. The resulting MC-3 membrane (with a MXene loading of 15.4 wt%) possesses the optimal separation performance, bearing a CO 2 permeability of 156.7 Barrer with ideal selectivities of 47.8 for CO 2 /CH 4 and 42.6 for CO 2 /N 2. For the mixed gas separation, the MC-3 membrane exhibits separation factors of 48.5 and 55.3 for CO 2 /N 2 and CO 2 /CH 4 , respectively. This excellent separation performance is resulted from the enhanced interfacial property, suitable MXene channel size and good CO 2 -solubility of nanocellulose. [ABSTRACT FROM AUTHOR]

Membrane-based gas separation technology is becoming increasingly attractive as a feasible alternative for carbon capture to alleviate global warming. Here, a double-salt deep eutectic solvent (DES) composed of organic salt (choline chloride) and inorganic salt (ZnCl 2) is designed. The as-prepared DES exhibits a superb affinity and compatibility with nanocellulose because of the interactions between salt ions and cellulose carboxyl/hydroxyl groups. Through a solvent impregnation process, the DES was integrated into the nanocellulose gel precursor and used as a facilitated transport agent to form the functionalized nanocellulose membrane. The DES is tightly attached to the cellulose fibers with a high uniformity in the membrane matrix. Gas separation tests demonstrated that the DES@nanocellulose membranes presented a maximum CO 2 permeability of 155.8 Barrer, with CO 2 /N 2 and CO 2 /CH 4 ideal selectivities of 43.6 and 48.4, respectively. Mixed gas separation tests were performed and the optimal membrane exhibited separation factors of 48.1 and 52.3 for CO 2 /N 2 and CO 2 /CH 4 , respectively. The membranes provide a high solubility for CO 2 due to the presence of abundant zinc ions, choline cations and carboxyl groups in the network, which can establish reversible coordination with CO 2 and promote CO 2 transport. [ABSTRACT FROM AUTHOR]

A facile one-step synthetic strategy is proposed here to realize simultaneous amine-functionalized and Fe-doping modification of ZIF-8, aiming to optimize the Lewis acidic and basic properties of ZIF-8 for enhanced CO 2 adsorption and subsequent cycloaddition reaction of CO 2 and epichlorohydrin under solvent-free and relatively mild conditions (0.1 MPa and 80 °C). The obtained Fe-ZIF-8-NH 2 exhibits an improved CO 2 adsorption capacity of 63 mmol/g as compared to that of 18 mmol/g for pristine ZIF-8 and delivers a high catalytic CO 2 cycloaddition efficiency with the yield of target product of 92%, much higher than that of Fe-ZIF-8 (80%), ZIF-8-NH 2 (62%) and pristine ZIF-8 (40%). The improved performance can be attributed to the introduction of abundant –NH 2 groups and Fe-doping that enrich the Lewis acidity and basicity. Moreover, the obtained Fe-ZIF-8-NH 2 also exhibits high chemical stability and satisfactory recycling ability, which makes the obtained sample a promising catalyst for CO 2 capture and utilization. [Display omitted] • Fe-ZIF-8-NH 2 is constructed by a one-step synthetic method. • The Lewis acidity and basicity of ZIF-8 are optimized. • Fe-ZIF-8-NH 2 exhibits an improved CO 2 adsorption capacity. • Fe-ZIF-8-NH 2 displays a satisfactory CO 2 cycloaddition efficiency. [ABSTRACT FROM AUTHOR]

Mixed matrix membranes (MMMs) combine the advantages of both polymers and inorganic fillers, and hold great promise for industrial gas separation. In this work, to enhance the interfacial compatibility between cellulose acetate (CA) matrix and ZIF-8 crystals, an interfacial design strategy was proposed by grafting polyethylenimine (PEI) onto ZIF-8 particles. The introduction of amine-rich PEI could regulate the surface property and maintain the pore accessibility of ZIF-8 crystals. In addition, the amine groups in PEI could interact with hydroxyl/carbonyl groups in CA chains to suppress the non-ideal voids at the ZIF-8/CA interface. With the aid of PEI, the interfacial compatibility between ZIF-8 and CA is substantially enhanced. Compared with pristine CA and ZIF-8@CA membranes, PEI grafted ZIF-8@CA (PZIF-8@CA) membrane exhibits a better gas separation performance, bearing a CO 2 permeability of 150.3 Barrer with CO 2 /N 2 and CO 2 /CH 4 ideal selectivities of 44.2 and 53.7, respectively. The separation mechanisms are attributed to the superior interfacial property, the good dispersion of ZIF-8 particles, the amine groups in PEI, and the high CO 2 solubility of the CA matrix. [Display omitted] • PEI grafted ZIF-8 (PZIF-8) is introduced into cellulose acetate to obtain MMMs. • PEI boosts the interfacial compatibility between ZIF-8 and cellulose acetate. • The optimal PZIF-8/CA membrane has a CO 2 permeability of 150.3 Barrer. • The membrane has CO 2 /N 2 and CO 2 /CH 4 ideal selectivities of 44.2 and 53.7 [ABSTRACT FROM AUTHOR]

Macroscopic MOF-based forests have been rationally fabricated via metal template-guided growth strategy for promoting CO 2 chemical transformation. [Display omitted] • A metal template-guided growth strategy is developed to give MOF forests. • ZIF-8 forests show superb catalytic performances toward CO 2 cycloaddition. • ZIF-8 forests can be easily recovered and reused at least ten times. • Activity can be maintained under mimic flue gas conditions or light irradiation. Construction of macroscopic metal–organic frameworks (MOFs) with high processability is crucial for their practical usage. Here, we demonstrate a facile metal template-guided growth approach that exploits the synthesis of forest-like ZIF-8-based material. The 3D self-supported array architecture endows the resultant ZIF-8 forests with efficient exposure of active sites, rapid mass transfer and simple recovery. Under mild catalytic reaction conditions (1 bar CO 2 , 60 ℃), ZIF-8 forests show remarkable activities toward the coupling of epoxides and CO 2 with an excellent cyclic carbonate yield of 96%, surpassing the powdered ZIF-8 crystals. Importantly, the catalytic performance can be well-maintained even after 10 cycles and under both simulated flue gas conditions and full-spectrum light irradiation, demonstrating the potential for practical catalysis. Our work provides a practical guideline to produce macroscopic MOF-based materials with great potential for industrial catalysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • A summary of low-concentration CO 2 capture and conversion over porous materials. • Key roles of porous materials in utilization of CO 2 from dilute sources. • The challenges and future trends of porous catalysts for conversion of diluted CO 2. Carbon accumulation has raised worldwide concerns due to the risks of climate change. In such cases, direct carbon dioxide (CO 2) capture and conversion from diluted sources has potential for negative carbon emission. Distinct from non-porous catalytic systems, the fascinating features of large specific surface area, highly exposed catalytic sites, varied structures and tunable functions make porous materials attractive candidates for integrating the process of capture and utilization of diluted CO 2. In this review, we firstly provide a brief overview of the recent developments of porous materials, including zeolites, metal–organic frameworks, porous organic polymers, porous carbon, and functionalized mesoporous materials and their applications for CO 2 adsorption at relatively low partial pressure. Afterwards, direct chemical transformation of diluted CO 2 over different porous catalysts is discussed with the emphasis of their diverse functional roles. This is followed by a brief summary of current challenges and our personal view on future directions of this field. [ABSTRACT FROM AUTHOR]

• Zn-ZIF-L was used to design catalysts with multiple active sites. • The obtained catalyst has rich oxygen surface groups. • The obtained catalyst displays high performance for CO 2 cycloaddition. Integration of Lewis acid and base sites and oxygen surface groups in one catalyst is favorable to promote CO 2 cycloaddition reaction. Here, Zn-ZIF-L was used as starting material to design one kind of catalyst with multiple active sites via pyrolysis and oxidization treatment. The well-dispersed ZnO nanoparticles and pyridinic nitrogen in nitrogen-doped carbon serve as Lewis acid and base sites to activate epoxide and CO 2 while oxygen surface groups help promote the ring-opening reaction of epoxides. Results show that Zn-ZIF-L derived catalyst displays high catalytic activities for CO 2 cycloaddition (6 h, 83% of yield) under mild conditions (70 °C and 0.1 MPa CO 2) and outperforms ZIF-8 derived catalyst. Moreover, the obtained catalyst also achieves a satisfactory photothermal catalysis of cycloaddition reaction under light irradiation (120 mW/cm2), which makes our sample a promising catalyst for CO 2 conversion. [ABSTRACT FROM AUTHOR]