Viologen‐Benzothiadiazole‐Based Porous Organic Polymers for High‐Performance Photoelectrochemical Supercapacitors

Isomeric sp2-C-conjugated porous organic polymer-mediated photo- and sono-catalytic detoxification of sulfur mustard simulant under ambient conditions

A Three-Dimensional Silicon-Diacetylene Porous Organic Radical Polymer

Porous organic polymers have been received considerable attention due to their heteroatom-containing structures and high surface areas, which can offer high electrochemical performance in energy applications. The majority of reported Tröger’s base-functionalized porous organic polymers have been applied as effective candidates for sensing and gas separation/adsorption, while their use as electrode materials in supercapacitors is rare. Here, a novel covalent microporous organic polymer containing carbazole and Tröger’s base CzT-CMOP has been successfully synthesized through the one-pot polycondensation of 9-(4-aminophenyl)-carbazole-3,6-diamine (Cz-3NH2) with dimethoxymethane. The polycondensation reaction’s regioselectivity was studied using spectroscopic analyses and electronic structure calculations that confirmed the polycondensation occurred through the second and seventh positions of the carbazole unit rather than the fourth and fifth positions confirmed by first-principles calculations. Our CzT-CMOP exhibited high thermal stability of approximately 463.5 °C and a relatively high Brunauer–Emmett–Teller surface area of 615 m2 g−1 with a nonlocal density functional theory’s pore size and volume of 0.48 cm3 g−1 and 1.66 nm, respectively. In addition, the synthesized CzT-CMOP displayed redox activity due to the existence of a redox-active carbazole in the polymer skeleton. CzT-CMOP revealed high electrochemical performance when used as active-electrode material in a three-electrode supercapacitor with an aqueous electrolyte of 6 M KOH, and it showed specific capacitance of 240 F g−1 at a current density of 0.5 A g−1 with excellent stability after 2000 cycles of 97% capacitance retention. Accordingly, such porous organic polymer appears to have a variety of uses in energy-related applications.

Porous organic polymers (POPs) are highly versatile materials that find applications in adsorption, separation, and catalysis. Herein, a feasibility study on the design and synthesis of POP supports with a tunable pore structure and high ethylene-polymerization activity was conducted by the selection of functional comonomers and template agents, and control of cross-linking degree of their frameworks. Functionalized POPs with a tunable pore structure were designed and synthesized by a dispersion polymerization strategy. The functional comonomers incorporated in the poly(divinylbenzene) (PDVB)-based matrix played a significant role in the porous structure and particle morphology of the prepared polymers, and a specific surface area (SSA) of 10–450 m2/g, pore volume (PV) of 0.05–0.5 cm3/g, bulk density with a range of 0.02–0.40 g/cm3 were obtained by the varied functional comonomers. Besides the important factors of thermodynamic compatibility of the selected solvent system, other factors that could be used to tune the pore structure and morphology of the POP particles have been also investigated. The Fe3O4 nanoaggregates as a template agent could help improve the porous structure and bulk density of the prepared POPs, and the highly cross-linking networks can dramatically increase the porous fabric of the prepared POPs. As for the immobilized metallocene catalysts, the pore structure of the prepared POPs had a significant influence on the loading amount of the Zr and Al of the active sites, and the typically highly porous structure of the POPs would contribute the immobilization of the active species. High ethylene-polymerization activity of 8033 kg PE/mol Zr h bar was achieved on the POPs-supported catalysts, especially when high Al/Zr ratios on the catalysts were obtained. The performance of the immobilized metallocene catalysts was highly related to the pore structure and functional group on the POP frameworks.

Porous organic polymers (POPs) are a class of materials composed of organic building blocks usually consisting of the elements C, H, O, N, and B and other light elements connected by covalent bonds. Owing to the diversity of synthesis methods in organic chemistry, POPs can be prepared by Suzuki coupling, Sonogashira-Hagihara cross-coupling, Schiff-base condensation, Knoevenagel condensation, and Friedel-Crafts alkylation. POPs show great application potential in the field of sample pretreatment because of their large specific surface area, adjustable pore size, high tailorability, and easy modification. The design of new functional building blocks is an important factor in advancing the development of POPs and is key to the efficient separation and enrichment of target molecules in complex substrates. In recent years, supramolecular-derived compounds have provided new inspiration and breakthroughs in the construction of POPs on account of their excellent host-guest recognition properties, simple functionalization strategies, and adjustable topological configurations. The "cavitand-to-framework" approach, that is, the knitting of 0D macrocycles into hierarchical 2D or 3D POPs using suitable linkers, and extension of the research scope of supramolecular chemistry from discrete cavities to rigidly layered porous organic frameworks can lead to significant improvements in the porosity and stability of supramolecular-derived compounds. They can also provide an effective means to expand the structural diversity of POPs and generate layered structures with high porosity. This review summarizes the preparation strategies and structural characteristics of supramolecular-derived POPs with different structures, such as crown ether-based POPs, cyclodextrin-based POPs, and calixarene-based POPs. The promising applications of these materials in sample pretreatment focusing on food analysis and environmental monitoring, including epoxides, organic dyes, heavy metals, algatoxins, halogens, and antibiotic drugs, are then summarized. Next, the extraction mechanisms mainly attributed to host-guest recognition, π-π stacking, and hydrogen-bonding and electrostatic interactions between the supramolecular structures and analytes are described. The key role and potential advantages of the different preparation strategies and structural characteristics of these POPs in sample pretreatment are also discussed. Finally, the future prospects and remaining challenges of supramolecular-derived POPs are proposed. Supramolecular-derived POPs can not only achieve the rapid and selective extraction of target analytes during sample pretreatment but also improve the extraction effect of online solid phase extraction technologies. However, although numerous supramolecular-derived POPs have been developed, few have been applied in the field of sample pretreatment. Thus, the expansion of the application potential of more POP materials requires further exploration and research. The design and synthesis of supramolecular-derived POPs with highly selective recognition performance remains an important research direction in the field of sample pretreatment.

Oxygen atoms have been widely used in porous organic polymers, which has attracted much attention from researchers. Herein, porous organic polymer with high oxygen content is synthesized with oxygen‐rich monomer as construction unit and anhydrous aluminum chloride as catalyst; then phase‐change materials (PCMs) composites are prepared by self‐adsorption method. The pore properties of the oxygen‐rich porous organic polymer are characterized by nitrogen absorption and desorption method. The properties of the PCM composites are characterized by scanning electron microscopy, X‐ray diffraction, Fourier‐transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The results show that the oxygen‐rich porous organic polymer has high Brunauer–Emmett–Teller surface area (465 m2 g−1) and excellent thermal stability. The PCM composites possess high encapsulation rate (50.6 wt%) and latent heat (124.7 kJ g−1). After several thermal cycles, the thermal properties of all PCM composites are almost unchanged, and no leakage phenomenon is found. It can be seen that oxygen‐rich porous polymers have potential applications in PCM adsorption and thermal energy storage.

Since the electrode/catalyst materials contribute to nearly half of a fuel cell stack cost, there is an urgent need to reduce or replace PGM usage. Among all the non-PGM candidates explored so far, transition metal doped nitrogen-carbon (TM-N-C) composites appear to be the most promising ones. Generally, these materials are prepared by forming TM-N4 molecular complex over amorphous carbon support, followed by thermal activation. Since non-PGM catalysts are known to have lower turn-over frequency per catalytic site comparing to platinum, their active site densities must be substantially higher to deliver a comparable performance. Using carbon support dilutes the active site density. The new approaches that could circumvent such limitation without the need of inert carbon support include the use of metal-organic framework (MOF) [1-3] and porous organic polymer (POP) [4] as the catalyst precursors. The materials derived from these rationally designed precursors can serve as high efficiency non-PGM catalysts directly or be further modified to low-PGM catalysts. To maximize the utilization of non-PGM or low-PGM catalytic centers requires an electrode structure that ensures efficient mass transport of reactant and product to and from the active site. Furthermore, the catalyst must be durable under accelerated aging conditions. . At Argonne National Laboratory, we pioneered the research of using MOFs and POPs as the precursors for non-PGM catalyst synthesis [1, 3, 4, 5]. MOFs have clearly-defined lattice structures through the metal-ligand coordination chemistry. The TM-N4 entities can be grafted into MOFs with very high ligation site densities. During thermal activation, the organic linkers are converted to electro-conductive carbon while maintaining porous framework, leading to catalysts with high surface areas and uniformly distributed catalytic sites. We demonstrated that zeolitic imidazolate framework, subclass of MOF, can used to prepare low-cost, highly active non-PGM catalysts. More recently, we developed a “one-pot” solid-state synthesis method which produces non-PGM catalyst using low-cost material without the need of solvent and separation [5]. Parallel to MOFs, we also developed another class of non-PGM catalysts using the porous organic polymers (POPs). [4] POPs are prepared by cross-linking the monomers containing strong TM-N binding site through polymerization. Similar to MOFs, POPs have high surface areas and uniformly distributed active sites inside the pours framework. The cathode catalysts prepared by MOF or POP have produced some major catalytic activity breakthroughs, generating the highest current and power densities among those reported in the literature. To improve mass and charge transfer for non-PGM catalysts, we have recently invented a new method to produce non-PGM catalyst with nano-network electrode architecture. [6] The MOF-based catalysts are incorporated into individual nano-fibers connected by a graphitic network. High micro-pore volume and surface area are maintained whereas the meso-pores in the conventional powder catalysts were no longer necessary and eliminated. Mass transport is improved through macro-pores inside the nano-network while the charge transfer is accomplished through the network of graphitic fibers. The new nano-network non-PGM catalyst has achieved excellent fuel cell performances in both activity and durability. Catalyst durability under fuel cell operating condition represents another critical challenge facing non-PGM and low-PGM catalyst development. We have recently developed a new approach to stabilize the catalyst performance. The new catalyst demonstrated less than 12% loss of mass activity at 0.9 V after 30,000 voltage cycles in a fuel cell test following DOE test protocol. Acknowledgement: The authors wish to thank Chen Chen and Lauren Grabstanowicz for her assistance in the MEA preparation. The work performed at Argonne is supported by DOE Fuel Cell Technologies Office and Office of Science.

Many porous organic polymers (POPs) possess excellent light absorption capacity and CO2 absorption performance owing to their conjugated skeletons and large specific surface area values. Some of these fascinating materials have inherent reaction sites for CO2 conversion and appropriate band structures to catalyze the CO2 reduction reaction. Therefore, these POPs have been used as heterogeneous catalysts in the photocatalytic CO2 reduction reaction. Among those POPs, four kinds of catalytic systems have been developed for realizing the CO2 photoreduction reaction: POPs loaded with noble metals, POPs loaded with non‐noble metals, POPs combined with inorganic semiconductors, and metal‐free POPs. Each of these catalytic systems has its own advantages and drawbacks. In general, the catalytic system of supported metals has higher catalytic efficiency but lower durability than metal‐free POPs. It should be noted that in the process of catalyst development, the co‐catalyst is gradually minimizing in POPs to achieve a more green CO2 photoreduction reaction. In this review, different types of POPs and the relationship between their structures and catalytic performance in the photocatalytic reduction of CO2 are summarized.

Recent advances in adsorptive removal and photocatalytic reduction of Cr(VI) by porous organic polymers (POPs)

Comprehensive SummaryAdvanced functionalization‐decorated porous organic polymers (POPs) are emerging as a prominent research focus, spanning from their construction to applications in gas storage and separation, catalysis, energy storage, electrochemistry, and other areas. Furthermore, the inherent organic nature, tailored pore structures, and adjustable chemical components of POPs offer a versatile platform for the incorporation of various metal active sites. Meticulously designed molecular building blocks can serve as organic ligands uniformly distributed throughout POPs, leading to the effective isolation of inorganic metal active sites at the molecular level. In this manner, POPs containing active metal centers bridge the gap between organic and inorganic scaffolds. This review aims to provide an overview of recent research progress on metal‐decorated POPs, focusing on strategies for incorporating metal active sites into POPs and their applications in adsorption, separation, catalysis, and photoelectrochemistry. Finally, current challenges and future prospects are discussed for further research. Key ScientistsAdvanced functionalized porous organic polymers have become a new research hotspot, ranging from their construction to their use in gas storage and separation, catalysis, energy storage, electrochemistry, and other applications. In 2002, the McKeown group was the first to report phthalocyanine‐based MPOPs with permanent porosity and a moderate surface area. In 2010, the Yu group prepared nanoporous polyporphyrin materials P(Fe‐TTPP) from the metallated porphyrin with functionalized thiophenyl groups by the FeCl3 catalyzed oxidation couple reaction showing the surface area of 1522 m2·g–1. Subsequently, in 2013, the Deng group was the first to use metalated salens as the original building blocks for preparing MPOPs. The Morin group was the first to produce a series of ferrocene‐based nanoporous frameworks via radical polymerization, with surface areas ranging from 385 to 899 m2·g–1. In 2016, the Han group synthesized two N‐pyridinylphenylcarbazole (PPC) ligands to produce a series of metalized polycarbazole networks. Recently, the Tan group reported a solvent‐knitting hyper‐cross‐linking reaction to produce HUST‐1, which contains a porphyrin unit. The porphyrin moiety provides a centered square‐planar metal post‐coordination site, resulting in the metalated HUST‐1‐Co, which exhibits high efficiency in the catalytic conversion of CO2. Additionally, the Kegnæs group combined the decomposition of the palladium complex with an in situ catalyzed polymerization reaction, enabling the confinement of nascent Pd particles in the developing polymer network. This review focuses on recent research progress in metal‐decorated POPs, emphasizing strategies for incorporating metal active sites into POPs and their applications.

Constructing porous organic polymer with hydroxyquinoline as electrochemical-active unit for high-performance supercapacitor

Global warming is a public alarming issue caused by extreme CO2 emissions. Thus, CO2 removing using TFN membranes is an effective method to improve the CO2 separation performance. Thin film nocomposite membranes composed of Pebax 1657 embedded by porous organic polymers over the porous polysulfone support used to separate CO2 from CH4 and N2 gases. Porous organic polymers were synthesized via Friedel-Crafts one-step reaction. The obtained results from field emission scanning electron microscopy and thermal gravimetric analysis revealed that the TFN membranes declared a superior compatibility between Pebax and fillers. Permeation properties of membranes were tested over various feed pressure with the range of 2–10 bar. Pure gases permeability, CO2/CH4 and CO2/N2 selectivities improved via adding porous organic polymers into the Pebax. At porous organic polymers loading of 5wt% and feed pressure of 2 bar, the CO2, CH4 and N2 permeability raised to 310.6, 27.6 and 4.5 Barrer, respectively; which exhibited a significant improvement compared to thin film composite membrane. Moreover, the CO2/CH4 and CO2/N2 selectivities also increased to 11.25 and 70.04; respectively. Obtained results reveladed that the membranes performance was enhanced as the feed gas pressure increased. TFN containing 5wt% porous organic polymers implies a CO2 permeability of 348.4 Barrer at feed pressure of 10 bar.

Porous organic polymers with different pore structures for sensitive solid-phase microextraction of environmental organic pollutants

Design and successful synthesis of phenolic-OH and amine-functionalized porous organic polymers as adsorbent for postcombustion CO2 uptake from flue gas mixtures along with high CO2/N2 selectivity is a very demanding research area in the context of developing a suitable adsorbent to mitigate greenhouse gases. Herein, we report three triazine-based porous organic polymers TrzPOP-1, -2, and -3 through the polycondensation of two triazine rings containing tetraamine and three dialdehydes. These porous organic polymers possess high Brunauer-Emmett-Teller (BET) surface areas of 995, 868, and 772 m2 g-1, respectively. Out of the three materials, TrzPOP-2 and TrzPOP-3 contain additional phenolic-OH groups along with triazine moiety and secondary amine linkages. At 273 K, TrzPOP-1, -2, and -3 displayed CO2 uptake capacities of 6.19, 7.51, and 8.54 mmol g-1, respectively, up to 1 bar pressure, which are considerably high among all porous polymers reported till date. Despite the lower BET surface area, TrzPOP-2 and TrzPOP-3 containing phenolic-OH groups showed higher CO2 uptakes. To understand the CO2 adsorption mechanism, we have further performed the quantum chemical studies to analyze noncovalent interactions between CO2 molecules and different polar functionalities present in these porous polymers. TrzPOP-1, -2, and -3 have the capability of selective CO2 uptake over that of N2 at 273 K with the selectivity of 61:1, 117:1, and 142:1 by using the initial slope comparing method, along with 108.4, 140.6, and 167.4 by using ideal adsorbed solution theory (IAST) method, respectively. On the other hand, at 298 K, the calculated CO2/N2 selectivities in the initial slope comparing method for TrzPOP-1, -2, and -3 are 27:1, 72:1, and 96:1, whereas those using IAST method are 42.1, 75.7, and 94.5, respectively. Cost effective and scalable synthesis of these porous polymeric materials reported herein for selective CO2 capture has a very promising future for environmental clean-up.

Porous organic polymers with defined morphologies: Synthesis, assembly, and emerging applications