Hierarchically Mesoporouso-Hydroxyazobenzene Polymers: Synthesis and Their Applications in CO2Capture and Conversion

Melamine sponges incorporated azo-linked porous organic polymer as adsorbent for extraction and determination of six B vitamins using pipette tip micro solid-phase extraction

A novel azo-linked porous organic polymer (AL-POP) was synthesized from caffeic acid and benzidine via an azo-coupling reaction and characterized by FTIR, SEM-EDS, BET, TGA, XRD and zeta potential analysis. AL-POPs were incorporated into melamine sponges and used for pipette tip micro solid-phase extraction (PT-MSPE) of six types of B vitamins (including thiamine, riboflavin, nicotinamide, pyridoxine, folic acid, and cyanocobalamin). After extraction, the samples were analyzed using high performance liquid chromatography-diode array detection (HPLC-DAD) system. The effect of AL-POP composition on the extraction efficiency (EE) of vitamins was investigated and benzidine to caffeic acid mol ratio of 1.5, 3.35 mmol of NaNO2, and reaction time of 8 h were selected as optimum conditions. The efficiency of the extraction process was improved by optimizing various parameters such as the amount of sorbent, pH and ionic strength of the sample, sample volume, number of sorption and desorption cycles, type of wash solvent, and type and volume of eluent solvent. Linearity (R2≥0.9987), Limit of detection (LOD) (11.88-18.97 ng/mL), limit of quantification (LOQ) (39.62-63.23 ng/mL), and enrichment factor (EF) (1.27-4.31) were obtained using calibration curves plotted under optimum conditions. Recovery values of these six B vitamins in the spiked multivitamin syrup samples varied from 80.01% to 108.35%, with a relative standard deviation (RSD) below 5.44%. Eventually, the optimized method was successfully used to extract and quantify the B vitamins in multivitamin syrup and non-alcoholic beer.

Recent Advances Hydrogenation of Carbon Dioxide to Light Olefins over Iron-Based Catalysts via the Fischer-Tropsch Synthesis

The massive burning of fossil fuels has been important for economic and social development, but the increase in the CO2 concentration has seriously affected environmental sustainability. In industrial and agricultural production, light olefins are one of the most important feedstocks. Therefore, the preparation of light olefins by CO2 hydrogenation has been intensively studied, especially for the development of efficient catalysts and for the application in industrial production. Fe-based catalysts are widely used in Fischer-Tropsch synthesis due to their high stability and activity, and they also exhibit excellent catalytic CO2 hydrogenation to light olefins. This paper systematically summarizes and analyzes the reaction mechanism of Fe-based catalysts, alkali and transition metal modifications, interactions between active sites and carriers, the synthesis process, and the effect of the byproduct H2O on catalyst performance. Meanwhile, the challenges to the development of CO2 hydrogenation for light olefin synthesis are presented, and future development opportunities are envisioned.

Photoresponsive Covalent Organic Frameworks: Visible-Light Controlled Conversion of Porous Structures and Its Impacts

Covalent organic frameworks are a novel class of crystalline porous polymers that enable molecular design of extended polygonal skeletons to attain well-defined porous structures. However, construction of a framework that allows remote control of pores remains a challenge. Here we report a strategy that merges covalent, noncovalent, and photo chemistries to design photoresponsive frameworks with reversibly and remotely controllable pores. We developed a topology-guided multicomponent polycondensation system that integrates protruded tetrafluoroazobenzene units as photoresponsive sites on pore walls at predesigned densities, so that a series of crystalline porous frameworks with the same backbone can be constructed to develop a broad spectrum of pores ranging from mesopores to micropores. Distinct from conventional azobenzene-based systems, the tetrafluoroazobenzene frameworks are highly sensitive to visible lights to undergo high-rate isomerization. The photoisomerization exerts profound effects on pore size, shape, number, and environment, as well as molecular uptake and release, rendering the system able to convert and switch pores reversibly and remotely with visible lights. Our results open a way to a novel class of smart porous materials with pore structures and functions that are convertible and manageable with visible lights.

Urea-rich porous organic polymer as a hydrogen bond catalyst for Knoevenagel condensation reaction and synthesis of 2,3-dihydroquinazolin-4(1H)-ones

In this research, a new urea-rich porous organic polymer (urea-rich POP) as a hydrogen bond catalyst was synthesized via a solvothermal method. The physiochemical properties of the synthesized urea-rich POP were investigated by using different analyses like Fourier transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), derivative thermogravimetry (DTG), energy-dispersive X-ray spectroscopy (EDS), elemental mapping analysis, X-ray diffraction analysis (XRD) and Brunauer-Emmett-Teller (BET) techniques. The preparation of urea-rich POP provides an efficacious platform for designing unique hydrogen bond catalytic systems. Accordingly, urea-rich POP, due to the existence of several urea moieties as hydrogen bond sites, has excellent performance as a catalyst for the Knoevenagel condensation reaction and multi-component synthesis of 2,3-dihydroquinazolin-4(1H)-ones.

Synthesis of azo-linked covalent organic polymers for pipette tip solid-phase extraction of sedative residues from animal tissues samples

Azo-linked covalent organic polymers (ACOPs) were synthesized by a simple azo reaction, with 2,2'-bis(trifluoromethyl)benzidine and 1,3,5-trihydroxybenzene as the monomers. The preparation process was mild, green, and environmental-friendly, avoiding the use of high temperature, metal catalysis, and harmful organic reagent. The obtained ACOPs were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, powder X-ray diffraction, and Brunauer-Emmett-Teller. With the prepared ACOPs as adsorbent, a method of pipette tip solid-phase extraction-liquid chromatography-tandem mass spectrometry detection (PTSPE-LC-MS/MS) was proposed for the analysis of target sedatives in animal tissues. Furthermore, the parameters for the extraction of five sedatives, including the amount of adsorbent, pH value, ion strength, elution solvent and volume, were investigated. Under the optimized conditions, the linear dynamic range was found from 0.1 to 10.0 μg kg-1, and the limits of detection were ranged from 0.02 to 0.1 μg kg-1. The method was assessed by the analysis of target sedatives in animal tissues, and the recoveries for the spiked pork muscle and pork liver samples were 84-102% and 83-101%, respectively. The results show that the developed method of PTSPE-LC-MS/MS with ACOPs as adsorbent is efficient for the analysis of trace sedatives in animal tissues.

A review on polyester and polyester-amide thin film composite nanofiltration membranes: Synthesis, characteristics and applications

Nanofiltration (NF) membranes have been widely used in various fields including water treatment and other separation processes, while conventional thin film composite (TFC) membranes with polyamide (PA) selective layers suffer the problems of fouling and chlorine intolerance. Due to the abundant hydrophilic hydroxyl groups and ester bonds free from chlorine attack, the TFC membranes composed of polyester (PE) or polyester-amide (PEA) selective layers have been proven to possess enhanced anti-fouling properties and superior chlorine resistance. In this review, the research progress of PE and PEA nanofiltration membranes is systematically summarized according to the variety of hydroxyl-containing monomers for membrane fabrication by the interfacial polymerization (IP) reaction. The synthesis strategies as well as the mechanisms for tailoring properties and performance of PE and PEA membranes are analyzed, and the membrane application advantages are demonstrated. Moreover, current challenges and future perspectives of the development of PE and PEA nanofiltration membranes are proposed. This review can offer guidance for designing high-performance PE and PEA membranes, thereby further promoting the efficacy of nanofiltration.

Tailoring of Textural Properties of 3D Reduced Graphene Oxide Composite Monoliths by Using Highly Crosslinked Polymer Particles toward Improved CO2 Sorption

The main constraint on developing a full potential for CO₂ adsorption of 3D composite monoliths made of reduced graphene oxide (rGO) and polymer materials is the lack of control of their textural properties, along with the diffusional limitation to the CO₂ adsorption due to the pronounced polymers' microporosity. In this work, the textural properties of the composites were altered by employing highly crosslinked polymer particles, synthesized by emulsion polymerization in aqueous media. For that aim, waterborne methyl methacrylate (MMA) particles were prepared, in which the crosslinking was induced by using different quantities of divinyl benzene (DVB). Afterward, these particles were combined with rGO platelets and subjected to the reduction-induced self-assembly process. The resulting 3D monolithic porous materials certainly presented improved textural properties, in which the porosity and BET surface area were increased up to 100% with respect to noncrosslinked composites. The crosslinked density of MMA polymer particles was a key parameter controlling the porous properties of the composites. Consequently, higher CO₂ uptake than that of neat GO structures and composites made of noncrosslinked MMA polymer particles was attained. This work demonstrates that a proper control of the microstructure of the polymer particles and their facile introduction within rGO self-assembly 3D structures is a powerful tool to tailor the textural properties of the composites toward improved CO₂ capture performance.

CeO2-ZrO2 Solid Solution Catalyzed and Moderate Acidic–Basic Sites Dominated Cycloaddition of CO2 with Epoxides: Halogen-Free Synthesis of Cyclic Carbonates

For the production of cyclic carbonates from the cycloaddition of CO2 with epoxides, halogen pollution and product purity are two of the most common problems due to the usage of homogeneous halogen-containing catalysts such as ammonium salt and alkali metal halide. Hence, the development of a novel, halogen-free and efficient catalyst for the synthesis of high-purity cyclic carbonates is significant. Here, a series of acid–base bifunctional Ce1-xZrxO2 nanorods were successfully prepared. The Ce1-xZrxO2 nanorods could catalyze the cycloaddition of CO2 with epoxides efficiently without any halogen addition. Especially for the Ce0.7Zr0.3O2 catalyst, a conversion of 96% with 100% 1,2-butylene carbonate selectivity was achieved. The excellent catalytic performance of Ce1-xZrxO2 nanorods is attributed to the formation of the CeO2-ZrO2 solid solution, which contributes to abundant moderate acidic–basic active sites on the catalyst surface. It is the synergistic effect of moderate acidic–basic sites that dominates the conversion of CO2 with epoxides, which will supply important references for the synthesis of efficient metal oxide catalyst for the cycloaddition of CO2 with epoxides.

One-pot construction of nitrogen-rich polymeric ionic porous networks for effective CO2 capture and fixation

Facile preparation of ionic porous networks (IPNs) with large and permanent porosity is highly desirable for CO₂ capture and transformation but remains a challenge. Here we report a one-pot base-mediated construction of nitrogen-rich IPNs through a combination of nucleophilic substitution and quaternisation chemistry from H-imidazole. This strategy, as proven by the model reactions of 1H-imidazole or 1-methyl-1H-imidazole with cyanuric chloride, allows for fine regulation of porosity and physicochemical properties, leading to nitrogen-rich IPNs featuring abundant ionic units and radicals. The as-prepared networks, termed IPN-CSUs, efficiently capture CO₂ (80.1 cc g^-1 at 273 K/1 bar) with an ideal CO₂/N₂ selectivity of 139.7. They can also effectively catalyse the cycloaddition reaction between CO₂ and epoxides with high yields of up to 99% under mild conditions (0.1 MPa, 298 K), suggesting their possible applications in the fields of both selective molecular separation and conversion. Unlike the previously known strategies generally involving single coupling chemistry, our strategy combining two coupling routes in one pot appears to be unique and potentially applicable to other building blocks.

Green Carbon Science: Efficient Carbon Resource Processing, Utilization, and Recycling Towards Carbon Neutrality

Green carbon science is defined as "Study and optimization of the transformation of carbon containing compounds and the relevant processes involved in the entire carbon cycle from carbon resource processing, carbon energy utilization, and carbon recycling to use carbon resources efficiently and minimize the net CO2 emission." [1] Green carbon science is related closely to carbon neutrality, and the relevant fields have developed quickly in the last decade. In this Minireview, we proposed the concept of carbon energy index, and the recent progresses in petroleum refining, production of liquid fuels, chemicals, and materials using coal, methane, CO2, biomass, and waste plastics are highlighted in combination with green carbon science, and an outlook for these important fields is provided in the final section.

Grotthuss Proton-Conductive Covalent Organic Frameworks for Efficient Proton Pseudocapacitors

Herein, we describe the synthesis of two highly crystalline, robust, hydrophilic covalent organic frameworks (COFs) that display intrinsic proton conduction by the Grotthuss mechanism. The enriched redox-active azo groups in the COFs can undergo a proton-coupled electron transfer reaction for energy storage, making the COFs ideal candidates for pseudocapacitance electrode materials. After in situ hybridization with carbon nanotubes, the composite exhibited a high three-electrode specific capacitance of 440 F g^-1 at the current density of 0.5 A g^-1 , among the highest for COF-based supercapacitors, and can retain 90 % capacitance even after 10 000 charge-discharge cycles. This is the first example using Grotthuss proton-conductive organic materials to create pseudocapacitors that exhibited both high power density and energy density. The assembled asymmetric two-electrode supercapacitor showed a maximum energy density of 71 Wh kg^-1 with a maximum power density of 42 kW kg^-1 , surpassing that of all reported COF-based systems.

Metalated Porous Phenanthroline-Based Polymers as Efficient Heterogeneous Catalysts for Regioselective C-H Activation of Heteroarenes

Direct C-H bond activation of heterocycles as a step-economical and environmentally friendly approach to build the heterobiaryls motifs is highly attractive, but it still has a challenge to design and prepare a cheap and regioselective heterogeneous catalyst. To tackle this challenge, we have introduced Ni species into a porous phenanthroline-based organic polymer donated as POP-Phen@Ni. This heterogeneous catalyst shows excellent catalytic performances in regioselective C-H activation of heterocycles, even better than those of the corresponding homogenous catalyst. H/D exchange experiments show that the lithium bis(trimethylsilyl)amide (LiHMDS), a base added in the reaction, play a very important role during the reaction processes. We believe that this heterogeneous catalyst would open a new door for design of heterogeneous catalysts to efficiently catalyze the regioselective C-H activation of heterocycles.

Study of Amine Functionalized Mesoporous Carbon as CO2 Storage Materials

Carbon sequestration via the carbon capture and storage (CCS) method is one of the most useful methods of lowering CO2 emissions in the atmosphere. Ethylenediamine (EDA)- and triethylenetetramine (TETA)-modified mesoporous carbon (MC) has been successfully prepared as a CO2 storage material. The effect of various concentrations of EDA or TETA added to MC, as well as activated carbon (AC), on their CO2 adsorption capacity were investigated using high-purity CO2 as a feed and a titration method to quantitatively measure the amount of adsorbed CO2. The results showed that within 60 min adsorption time, MCEDA49 gave the highest CO2 capacity adsorption (19.68 mmol/g), followed by MC-TETA30 (11.241 mol/g). The improvement of CO2 adsorption capacity at low TETA loadings proved that the four amine functional groups in TETA gave an advantage to CO2 adsorption. TETA-functionalized MC has the potential to be used as a CO2 storage material at a low concentration. Therefore, it is relatively benign and friendly to the environment.

Carbon Dioxide Conversion Upgraded by Host-guest Cooperation between Nitrogen-Rich Covalent Organic Framework and Imidazolium-Based Ionic Polymer

The chemical conversion of CO₂ into value-added chemicals is one promising approach for CO₂ utilization. It is crucial to explore highly efficient catalysts containing task-specific components for CO₂ fixation. Here, a host-guest catalytic system was developed by integrating nitrogen-rich covalent organic framework (TT-COF) and imidazolium-based ionic polymer (ImIP), which serve as hydrogen-bonding donor and nucleophilic agent, respectively, for cooperatively facilitating the activation of the epoxides and subsequent CO₂ cycloaddition. The catalytic activity of the host-guest system was remarkably superior to those of ImIP, TT-COF, and their physical mixture. Furthermore, selective adsorption for CO₂ over N₂ rendered this catalytic system effective for the cycloaddition reaction of the simulated flue gas. The protocols for the unification of two catalytically active components provide new opportunities for the development of composite systems in multiple applications.

Building N-Heterocyclic Carbene into Triazine-Linked Polymer for Multiple CO2 Utilization

The development of new CO₂ detection technologies and CO₂ "capture-conversion" materials is of great significance due to the growing environmental crisis. Here, multifunctional triazine-linked polymers with built-in N-heterocyclic carbene (NHC) sites (designated as NHC-triazine@polymer) are presented for simultaneous CO₂ detection, capture, activation, and catalytic conversion. NHC-triazine@polymer were readily obtained through polymerization of cyanophenyl-substituted NHC. The obtained film-like polymers exhibited interesting CO₂ -triggered fluorescence "turn-on" response and CO₂ -sensitive reversible color change. Both NHC and triazine sites could act as efficient binding sites for CO₂ , and the CO₂ uptake of NHC and triazine reached 1.52 and 1.36 mmol g^-1 , respectively. Notably, after being captured by NHC, CO₂ was activated into a zwitterionic adduct NHC-CO₂ that could be easily transformed into cyclic carbonate in the presence of epoxides. Moreover, NHC-triazine@polymer were stable and active catalysts for the conversion of low-concentration CO₂ in a gas mixture (7 vol %) into cyclic carbonates as well as for hydrosilylation of CO₂ to formamides.

Triazine-based Organic Polymer-catalysed Conversion of Epoxide to Cyclic Carbonate under Ambient CO2 Pressure

In this work we have achieved epoxide to cyclic carbonate conversion using a metal-free polymeric catalyst under ambient CO₂ pressure (1.02 atm) using a balloon setup. The triazine containing polymer (CYA-ANIS) was prepared from cyanuric chloride (CYA-Cl) and o-dianisidine (ANIS) in anhydrous DMF as solvent by refluxing under the N₂ gas environment. The presence of triazine and amine functional groups in the polymer results in the adsorption of CO₂ up to 7 cc/g at 273 K. This inspired us to utilize the polymer for the conversion of a series of functionalised epoxides into their corresponding cyclic carbonates in the presence of tetrabutyl ammonium iodide (TBAI) as co-catalyst. The product has wide range of applications like solvent in lithium ion battery, precursor for polycarbonate, etc. The catalyst was efficient for the conversion of different mono and di-epoxides into their corresponding cyclic carbonates under atmospheric pressure in the presence of TBAI as co-catalyst. The study indicates that epoxide attached with electron withdrawing groups (like, CH₂ Cl, glycidyl ether, etc.) displayed better conversion compared to simple alkane chain attached epoxides. This is mainly due to the stabilization of electron rich intermediates produced during the reaction (e. g. epoxide ring opening or CO₂ incorporation into the halo-alkoxide anion). This catalyst mixture was capable to maintain its reactivity up to five cycles without losing its activity. Post catalytic characterization clearly supports the heterogeneous and recyclable nature of the catalyst.

Ionic-Liquid-Modified Click-Based Porous Organic Polymers for Controlling Capture and Catalytic Conversion of CO2

Capture and catalytic conversion of CO₂ into value-added chemicals is a promising and sustainable approach to relieve global warming and the energy crisis. Nitrogen-rich porous organic polymers (POPs) are promising materials for CO₂ capture and separation, but their application in the additive-free catalytic conversion of CO₂ into cyclic carbonates is still a challenge. Herein, a nitrogen-rich click-based POP (CPP) was developed for the cycloaddition reaction of CO₂ with epoxides in the absence of metal, solvents, and additives. The introduction of imidazolium-based ionic liquids on the CPP host backbone could modulate the porosity, CO₂ adsorption/desorption, CO₂ selectivity over N₂ , and catalytic activity in the chemical transformation. A tentative catalytic pathway was proposed to account for the superior catalytic activity of the catalytic systems, in which the incorporated ionic liquid and porous properties of CPP synergistically contributed to the catalytic reaction. This study provides a platform to understand the cooperative effects of porous properties and nucleophilic anions on the cycloaddition reaction of CO₂ with epoxides.

Facile Incorporation of Au Nanoparticles into an Unusual Twofold Entangled Zn(II)-MOF with Nanocages for Highly Efficient CO2 Fixation under Mild Conditions

Herein, a new porous Zn(II)-based metal-organic framework (MOF 1) has been prepared, the structure of which featured a twofold entangled motif based on two typical secondary building units (SBUs). The gas sorption studies indicated that MOF 1 may be explored as a useful platform to encapsulate metallic nanoparticles. Then the Au@1 composite has been prepared via a facile incorporation method without extra reducing agents. The Au@1 composite has been fully characterized by HRTEM, SEM-EDX, PXRD, gas sorption, XPS, ICP, etc. Catalytic experiments showed that the Au@1 composite had a perfect catalytic performance in CO₂ fixation for epoxides with different substituents under mild conditions.

Imidazolium-Salt-Functionalized Covalent Organic Frameworks for Highly Efficient Catalysis of CO2 Conversion

The conversion of CO₂ into valuable chemicals is an ideal pathway for CO₂ utilization in industry, although the development of highly efficient catalysts remains a challenge. Herein, the design and synthesis of two covalent organic frameworks (COFs) functionalized with imidazolium salts were reported as catalysts for CO₂ conversion. The resultant COFs possessed highly crystalline structures, showed high stability and surface area, and contained dense catalytic active sites on the pore walls. They exhibited outstanding catalytic performances for the reaction of CO₂ with epoxides without any solvent or cocatalyst under mild conditions and afforded a record turnover number of 495 000. In addition, the COFs could serve as effective catalysts in the reductive reaction of CO₂ with amines. The results presented here thus demonstrate the exceptional potential of the functionalized COFs for various challenging CO₂ transformations.

Hierarchical Porous and Zinc-Ion-Crosslinked PIM-1 Nanocomposite as a CO2 Cycloaddition Catalyst with High Efficiency

CO₂ cycloaddition to epoxides is an effective and economical utilization method to alleviate the current excessive CO₂ emission situation. The development of catalysts with both high catalytic efficiency and high recyclability is necessary but challenging. In this context, a heterogeneous catalyst was synthesized based on a zinc-ion-crosslinked polymer with intrinsic microporosity (PIM-1). The high microporosity of PIM-1 promoted a high Zn²⁺ loading rate. Additionally, the relatively stable ionic bond formed between Zn²⁺ and the PIM-1 framework through electrostatic interaction ensured high loading stability. In the process of CO₂ cycloaddition with propylene epoxide, an optimized conversion of 90 % with a turnover frequency as high as 9533 h^-1 could be achieved within 0.5 h at 100 °C and 2 MPa. After 15 cycles, the catalytic efficiency did not demonstrate a significant decline, and the catalyst was able to recover most of its activity after Zn²⁺ reloading. This work thereby provides a strategically designed CO₂ conversion catalyst based on an ionic crosslinked polymer with intrinsic microporosity.

Ordered Porous Poly(ionic liquid) Crystallines: Spacing Confined Ionic Surface Enhancing Selective CO2 Capture and Fixation

Porous poly(ionic liquid)s (PPILs) combine the features of porous materials, polymers, and ionic liquids (ILs) or their derivatives, but they are normally of amorphous structure with disordered pores. Here, we report the facile synthesis of ordered porous poly(ionic liquid) crystallines (OPICs, specialized as a kind of PPIL analogues) with diverse and adjustable framework IL moieties through the Schiff base condensation of IL-derived ionic salts and neutral monomers. Ternary monomer mixtures are employed to artistically control the chemical composition and pore configurations. Compact atomic packing was achieved to give spacing confined ionic surface with strong CO₂ affinity. Through monomer control, OPICs exhibit high CO₂ uptakes with excellent CO₂/N₂(CH₄) selectivities and efficiently implement CO₂ fixation through catalyzing epoxides cycloaddition under down to ambient conditions.

Porous Graphene Oxide/Porous Organic Polymer Hybrid Nanosheets Functionalized Mixed Matrix Membrane for Efficient CO2 Capture

The computational simulation of porous graphene oxide (PGO) indicated that it has great potential for the preparation of gas separation membranes. However, scaling up the manufacture of multilayer, defect-free porous graphene oxide membrane with consistently sized nanopores is extremely challenging. Here, we prepared layer-by-layer CO₂-philic Pebax^@1657 membranes that were functionalized by o-hydroxyazo-hierarchical porous organic polymers (o-POPs) and PGO. The d-spacing of pristine PGO could be finely regulated through CO₂-philic o-POPs to facilitate the permeability of CO₂. In addition, the o-POPs exhibit "N₂-phobic, CO₂-philic" properties with the phenolic hydroxyl and the azo group. The best of the POP-PGO membrane exhibits that the CO₂ permeability and ideal selectivity of CO₂/N₂ are 232.7 Barrer and 80.7, respectively, and it has surpassed the Robeson's upper bound (2008).

Imidazolium- and Triazine-Based Porous Organic Polymers for Heterogeneous Catalytic Conversion of CO2 into Cyclic Carbonates

CO₂ adsorption and concomitant catalytic conversion into useful chemicals are promising approaches to alleviate the energy crisis and effects of global warming. This is highly desirable for developing new types of heterogeneous catalytic materials containing CO₂ -philic groups and catalytic active sites for CO₂ chemical transformation. Here, we present an imidazolium- and triazine-based porous organic polymer with counter chloride anion (IT-POP-1). The porosity and CO₂ affinity of IT-POP-1 may be modulated at the molecular level through a facile anion-exchange strategy. Compared with the post-modified polymers with iodide and hexafluorophosphate anions, IT-POP-1 possesses the highest surface area and the best CO₂ uptake capacity with excellent adsorption selectivity over N₂ . The roles of the task-specific components such as triazine, imidazolium, hydroxyl, and counter anions in CO₂ absorption and catalytic performance were illustrated. IT-POP-1 exhibits the highest catalytic activity and excellent recyclability in solvent- and additive-free cycloaddition reaction of CO₂ with epoxides.

Solvent-Free Self-Assembly to the Synthesis of Nitrogen-Doped Ordered Mesoporous Polymers for Highly Selective Capture and Conversion of CO2

A solvent-free induced self-assembly technology for the synthesis of nitrogen-doped ordered mesoporous polymers (N-OMPs) is developed, which is realized by mixing polymer precursors with block copolymer templates, curing at 140-180 °C, and calcination to remove the templates. This synthetic strategy represents a significant advancement in the preparation of functional porous polymers through a fast and scalable yet environmentally friendly route, since no solvents or catalysts are used. The synthesized N-OMPs and their derived catalysts are found to exhibit competitive CO₂ capacities (0.67-0.91 mmol g^-1 at 25 °C and 0.15 bar), extraordinary CO₂ /N₂ selectivities (98-205 at 25 °C), and excellent activities for catalyzing conversion of CO₂ into cyclic carbonate (conversion >95% at 100 °C and 1.2 MPa for 1.5 h). The solvent-free technology developed in this work can also be extended to the synthesis of N-OMP/SiO₂ nanocomposites, mesoporous SiO₂ , crystalline mesoporous TiO₂ , and TiPO, demonstrating its wide applicability in porous material synthesis.

A Reversed Photosynthesis-like Process for Light-Triggered CO2 Capture, Release, and Conversion

Materials for CO₂ capture have been extensively exploited for climate governance and gas separation. However, their regeneration is facing the problems of high energy cost and secondary CO₂ contamination. Herein, a reversed photosynthesis-like process is proposed, in which CO₂ is absorbed in darkness while being released under light illumination. The process is likely supplementary to natural photosynthesis of plants, in which, on the contrary, CO₂ is released during the night. Remarkably, the material used here is able to capture 9.6 wt.% CO₂ according to its active component. Repeatable CO₂ capture at room temperature and release under light irradiation ensures its convenient and cost-effective regeneration. Furthermore, CO₂ released from the system is successfully converted into a stable compound in tandem with specific catalysts.

Charged Metalloporphyrin Polymers for Cooperative Synthesis of Cyclic Carbonates from CO2 under Ambient Conditions

A facile and one-pot synthesis of metalloporphyrin-based ionic porous organic polymers (M-iPOPs) was performed through a typical Yamamoto-Ullmann coupling reaction for the first time. We used various characterization techniques to demonstrate that these strongly polar Al-based materials (Al-iPOP) possessed a relatively uniform microporosity, good swellable features, and a good CO₂ capture capacity. If we consider the particular physicochemical properties, heterogeneous Al-iPOP, which bears both a metal active center and halogen anion, acted as a bifunctional catalyst for the solvent- and additive-free synthesis of cyclic carbonates from various epoxides and CO₂ with an excellent activity and good recyclability under mild conditions. Interestingly, these CO₂ -philic materials could catalyze the cycloaddition reaction smoothly by using simulated flue gas (15 % CO₂ in N₂ , v/v) as a raw material, which indicates that a stable local microenvironment and polymer swellability might promote the transformation. Thus, the introduction of polar ionic liquid units into metalloporphyrin-based porous materials is regarded as a promising new strategy for the chemical conversion of CO₂ .

Metal-Organic Framework-Templated Catalyst: Synergy in Multiple Sites for Catalytic CO2 Fixation

The types and quantities of active sites play a critical role in catalysis. Herein, ZnO nanoparticles encapsulated into N-doped porous carbon has been rationally prepared by the pyrolysis of a metal-organic framework (MOF) followed by a moderate oxidation treatment. The resulting catalyst exhibits excellent activity, selectivity, and recyclability in the CO₂ cycloaddtion reactions with epoxides owing to the synergy of multiple sites inherited from the MOF and generated by the oxidation process.

Metallosalen-Based Ionic Porous Polymers as Bifunctional Catalysts for the Conversion of CO2 into Valuable Chemicals

A series of new metallosalen-based ionic porous organic polymers (POPs) were synthesized for the first time using a simple unique strategy based on the free-radical copolymerization reaction. Various techniques were used to characterize the physicochemical properties of these catalysts. These well-designed materials endowed high surface area, hierarchical porous structures, and enhanced CO₂ /N₂ adsorptive selectivity. Moreover, these POPs having both metal centers (Lewis acid) and ionic units (nucleophile) could serve as bifunctional catalysts in the catalytic conversion of CO₂ into high value-added chemicals without any additional co-catalyst under mild and solvent-free conditions, for example, CO₂ /epoxides cycloaddition and Nformylation of amines from CO₂ and hydrosilanes. The results demonstrated that the irregular porous structure was very favorable for the diffusion of substrates and products, and the microporous structural property resulted in the enrichment of CO₂ near the catalytic centers in the CO₂ -involved transformations. Additionally, the superhydrophobic property could not only enhance the chemoselectivity of products but also promote the stability and recyclability of catalysts.

A Hierarchical Bipyridine-Constructed Framework for Highly Efficient Carbon Dioxide Capture and Catalytic Conversion

As a C₁ feedstock, CO₂ has the potential to be uniquely highly economical in both a chemical and a financial sense. Porous materials bearing particular binding and active sites that can capture and convert CO₂ simultaneously are promising candidates for CO₂ utilization. In this work, a bipyridine-constructed polymer featuring a high surface area, a hierarchical porous structure, and excellent stability was synthesized through free-radical polymerization. After metalation, the resultant catalysts exhibited superior activities in comparison with those of their homogeneous counterparts in the cycloaddition of CO₂ to epoxides. The high performance of the heterogeneous catalysts originates from cooperative effects between the CO₂ -philic polymer and the embedded metal species. In addition, the catalysts showed excellent stabilities and are readily recyclable; thus, they are promising for practical utilization for the conversion of CO₂ into value-added chemicals.

Porous Ionic Polymers as a Robust and Efficient Platform for Capture and Chemical Fixation of Atmospheric CO2

Direct use of atmospheric CO₂ as a C₁ source to synthesize high-value chemicals through environmentally benign processes is of great interest, yet challenging. Porous heterogeneous catalysts that are capable of simultaneously capturing and converting CO₂ are promising candidates for such applications. Herein, a family of organic ionic polymers with nanoporous structure, large surface area, strong affinity for CO₂ , and very high density of catalytic active sites (halide ions) was synthesized through the free-radical polymerization of vinylfunctionalized quaternary phosphonium salts. The resultant porous ionic polymers (PIPs) exhibit excellent activities in the cycloaddition of epoxides with atmospheric CO₂ , outperforming the corresponding soluble phosphonium salt analogues and ranking among the highest of known metal-free catalytic systems. The high CO₂ uptake capacity of the PIPs facilitates the enrichment of CO₂ molecules around the catalytic centers, thereby benefiting its conversion. We have demonstrated for the first time that atmospheric CO₂ can be directly converted to cyclic carbonates at room temperature using a heterogeneous catalytic system under metal-solvent free conditions. Moreover, the catalysts proved to be robust and fully recyclable, demonstrating promising potential for practical utilization for the chemical fixation of CO₂ . Our work thereby paves a way to the advance of PIPs as a new type of platform for capture and conversion of CO₂ .