Metal organic polymers with dual catalytic sites for oxygen reduction and oxygen evolution reactions

Metal-organic frameworks and covalent organic frameworks have been widely employed in electrochemical catalysis owing to their designable skeletons,controllable porosities,and well-defined catalytic centers.However,the poor chemical stability and low electron conductivity limited their activity,and single-functional sites in these frameworks hindered them to show multifunctional roles in catalytic systems.Herein,we have constructed novel metal organic polymers(Co-HAT-CN and Ni-HAT-CN)with dual catalytic centers(metal-N_(4) and metal-N_(2))to catalyze oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).By using different metal centers,the catalytic activity and selectivity were well-tuned.Among them,Co-HAT-CN catalyzed the ORR in a 4e^(-)pathway,with a half-wave potential of 0.8 V versus RHE,while the Ni-HAT-CN catalyze ORR in a 2e^(-)pathway with H_(2)O_(2) selectivity over 90%.Moreover,the Co-HAT-CN delivered an overpotential of 350 mV at 10 mA cm^(-2) with a corresponding Tafel slope of 24 mV dec^(-1) for OER in a 1.0 M KOH aqueous solution.The experimental results revealed that the activities toward ORR were due to the M-N_(4) sites in the frameworks,and both M-N_(4) and M-N_(2) sites contributed to the OER.This work gives us a new platform to construct bifunctional catalysts.

Ultrathin organic polymer with p-πconjugated structure for simultaneous photocatalytic disulfide bond generation and CO_(2)reduction

Combining photocatalytic organic reactions with CO_(2)reduction is an efficient solar energy utilization mode,but it is still limited by the organic species that can be matched and the low conversion.Herein,ultrathin organic polymer with p-πconjugated structure(TPP)was rationally designed and prepared,and showed a high yield of CO(15.2 mmol g^(-1))and conversion of SAS coupled products(100%),far exceeding the organic polymer with P=O structure.The enhanced photoredox activity of TPP is ascribed to the orbital interaction between the p-orbital on phosphorus and theπ-orbitals of aromatic,which can accelerate the photoinduced charge carrier separation and improve the CO_(2)adsorption capacity.TPP can also be used for the dehydrocoupling of various benzyl mercaptans to the corresponding SAS bond products.This work provides a new concept for the efficient synthesis of disulfide bonds combined with CO_(2)reduction in a photoreaction system.

Ultrathin polyamide nanofiltration membrane prepared by triazine-based porous organic polymer as interlayer for dye removal

Separation membrane with high flux is generally encouraged in industrial application,because of the tremendous needs for decreasing membrane areas,usage costs and space requirements.The most effective and direct method for obtaining the high flux is to decrease membrane thickness.Polyamide(PA)nanofiltration membrane is conventionally prepared by the direct interfacial polymerization(IP)on substrate surface,and results in a thick PA layer.In this work,we proposed a strategy that constructing triazine-based porous organic polymer(TRZ-POP)as the interlayer to prepare the ultrathin PA nanofiltration membranes.TRZ-POP is firstly deposited on the polyethersulfone substrate,and then the formed TRZ-POP provides more adhesion sites towards PA based on its high specific surface areas.The chemical bonding between terminal amine group of TRZ-POP and the amide group of PA further improves the binding force,and strengthens the stability of PA layer.More importantly,the high porosity of TRZPOP layer causes the higher polymerization of initial PA owning to the stored sufficient amino monomer;and H-bonding interaction between amine groups of TRZ-POP and piperazine(PIP)can astrict the release of PIP.Thus,IP process is controlled,and the thinnest thickness of prepared PA layer is only<15 nm.As expected,PA/TRZ-POP membrane shows a more excellent water flux of 1414 L·m^(-2)·h^(-1)·MPa^(-1)than that of the state-of-the-art nanofiltration membranes,and without sacrificing dye rejection.The build of TRZPOP interlayer develops a new method for obtaining a high-flux nanofiltration membrane.

An Environment-Friendly High-Performance Aqueous Mg-Na Hybrid-Ion Battery Using an Organic Polymer Anode

Aqueous Mg ion batteries(AMIBs)show great potential in energy storage for their advantages of high capacity,abundant resource,and environmental friendliness.However,the development of AMIBs is limited due to the scarcity of suitable anode materials.In this study,a new polymer anode material(PNTAQ)with flower-like nanosheet structure is synthesized for aqueous Mg-Na hybrid-ion battery(AMNHIB).PNTAQ possess carbonyl functional groups which can be oxidized and reduced reversibly in aqueous solution containing alkaline metal ions.PNTAQ displays a discharge specific capacity of 245 mAh g^(−1)at 50 mA g^(−1)in 1 M MgCl_(2)+0.5 M NaCl electrolyte,which is much higher than that in single 1 M MgCl_(2)or 0.5 M NaCl electrolyte.Even cycling at 1000 mA g^(−1)for 1000 times,the capacity retention can still maintain at 87.2%.A full Mg-Na hybrid-ion cell is assembled by employingβ-MnO_(2)as cathode and PNTAQ as anode material,it exhibits a specific capacity of 91.6 mAh g^(−1)at 100 mA g^(−1).The polymer electrode material well maintains its framework structure during the discharge/charge cycling process of the hybrid-ion battery.

Preparation and characterization of organic polymer modified composite polyaluminum chloride

Compared with traditional aluminum salts, polyaluminum chloride （PACI） has better coagulation-flocculation performance in turbidity removal. However, it is still inferior to organic polymers in terms of bridging function. In order to improve the aggregating property of PACl, different composite PACl flocculants were prepared with various organic polymers. The effect of organic polymer on the distribution or Al（Ⅲ） species in composite flocculants was studied using ^27TAl NMR and Al-ferron complexation methods. The charge neutralization and surface adsorption characteristics of composite flocculants were also investigated. Jar tests were conducted to evaluate the turbidity removal efficacy of organic polymer modified composite flocculants. The study shows that cationic polymer and anionic polymer have significant influences on the coagulation-flocculation behaviors of PACl. Both cationic and anionic polymers can improve the turbidity removal performancc of PACl but the mechanisms arc much different： cationic organic polymer mainly increases the charge neutralization ability, but anionic polymer mainly enhances the bridging function.

Recent progress in porous organic polymers and their application for CO_(2) capture

Carbon capture,storage,and utilization(CCSU)is recognized as an effective method to reduce the excessive emission of CO_(2).Absorption by amine aqueous solutions is considered highly efficient for CO_(2) capture from the flue gas because of the large CO_(2) capture capacity and high selectivity.However,it is often limited by the equipment corrosion and the high desorption energy consumption,and adsorption of CO_(2) using solid adsorbents has been receiving more attention in recent years due to its simplicity and high efficiency.More recently,a great number of porous organic polymers(POPs)have been designed and constructed for CO_(2) capture,and they are proven promising solid adsorbents for CO_(2) capture due to their high Brunauer-Emmett-Teller(BET)surface area(SBET),adjustable pore size and easy functionalization.In particular,they usually have rigid skeleton,permanent porosity,and good physiochemical stability.In this review,we have a detailed review for the different POPs developed in recent years,not only the design strategy,but also the special structure for CO_(2) capture.The outlook of the opportunities and challenges of the POPs is also proposed.

Boosting selective C_(2)H_(2)/CH_(4),C_(2)H_(4)/CH_(4) and CO_(2)/CH_(4) adsorption performance via 1,2,3-triazole functionalized triazine-based porous organic polymers

Nitrogen-rich porous organic polymers have shown great potentials in gas adsorption/separation,photocatalysis,electrochemistry,sensing and so on.Herein,1,2,3-triazole functionalized triazine-based porous organic polymers(TT-POPs)have been synthesized by the copper-catalyzed azide-alkyne cycloaddition(Cu-AAC)polymerization reactions of 1,3,5-tris(4-azidophenyl)-triazine with 1,4-diacetylene benzene and 1,3,5-triacetylenebenzene,respectively.The characterizations of N2 adsorption at 77 K show TTPOPs possess permanent porosity with BET surface areas of 666 m^(2)·g^(-1)(TT-POP-1)and 406 m^(2)·g^(-1)(TT-POP-2).The adsorption capacities of TT-POPs for CO_(2),CH4,C2H2 and C2H4,as well as the selective separation abilities of CO_(2)/N2,CO_(2)/CH_(4),C_(2)H_(2)/CH_(4) and C_(2)H_(4)/CH_(4) were evaluated.The gas selective separation ratio of TT-POPs was calculated by the ideal adsorbed solution theory(IAST)method,wherein the selective separation ratios of C_(2)H_(2)/CH_(4) and C_(2)H_(4)/CH_(4) of TT-POP-2 was 48.4 and 13.6(298 K,0.1 MPa),which is comparable to other adsorbents(5.6–120.6 for C_(2)H_(2)/CH_(4),10–26 for C_(2)H_(4)/CH_(4)).This work shows that the 1,2,3-triazole functionalized triazine-based porous organic polymer has a good application prospect in natural gas purification.

Ferrimagnetism and metal insulator transition in an organic polymer chain

The ferrimagnetism and quantum phase transition of a bipartite lozenge periodic Anderson-like organic polymer, in which the localized f electrons hybridize with the odd site conduction orbitals, are investigated by means of Green＇s function theory. The ground state turns out to be gapless ferrimagnetism. At a finite temperature, the ferrimagnetic-to- paramagnetic phase transition takes place. The Kondo screenings and Ruderman-Kittel-Kasuya-Yosida （RKKY） inter- action can reduce and increase the transition temperature, respectively. Two Kondo screenings compete with each other, giving rise to the localized f electron spin screened antiferromagnetically. Accordingly, in a magnetic field, all spins are aligned along the chain easily, which is associated with metal-insulator transition. Furthermore, in a temperature-field plane, we reveal the gapless and spin polarized phases, which are characterized by susceptibility and specific heat, and whose behaviours are determined by the competition between the up-spin and down-spin hole excitations.

Electron push-pull effects induced performance promotion in covalent organic polymer thin films-based memristor for neuromorphic application

Covalent organic polymer(COP)thin film-based memristors have generated intensive research interest,but the studies are still in their infancy.Herein,by controlling the content of hydroxyl groups in the aldehyde monomer,Py-COP thin films with different electronic push-pull effects were fabricated bearing distinct memory performances,where the films were prepared by the solid-liquid interface method on the ITO substrates and further fabricated as memory devices with ITO/Py-COPs/Ag architectures.The Py-COP-1-based memory device only exhibited binary memory behavior with an ON/OFF ratio of 1:10^(1.87).In contrast,the device based on Py-COP-2 demonstrated ternary memory behavior with an ON/OFF ratio of 1:10^(0.6):10^(3.1) and a ternary yield of 55%.The ternary memory mechanism of the ITO/Py-COP-2/Ag memory device is most likely due to the combination of the trapping of charge carriers and conductive filaments.Interestingly,the Py-COPs-based devices can successfully emulate the synaptic potentiation/depression behavior,clarifying the programmability of these devices in neuromorphic systems.These results suggest that the electronic properties of COPs can be precisely tuned at the molecular level,which provides a promising route for designing multi-level memory devices.

Polarization engineering in porous organic polymers for charge separation efficiency and its applications in photocatalytic aerobic oxidations

Photocatalytic aerobic oxidation reactions are largely governed by the efficiency of charge separation and subsequent reactive oxygen species(ROS) generation. Herein, we report a polarization engineering strategy to promote the charge separation and ROS generation efficiency by substituting the benzene unit with furan/thiophene in porous organic polymers(POPs). Benefiting from the extent of local polarization, the thiophene-containing POP(JNU-218) exhibits the best photocatalytic performance in aerobic oxidation reactions, with a yield much higher than those for the furan-containing POP(JNU-217) and the benzenecontaining POP(JNU-216). Experimental studies and theoretical calculations reveal that the increase of local polarization can indeed reduce the exciton binding energy, and therefore facilitate the separation of electron-hole pairs. This work demonstrates a viable strategy to tune charge separation and ROS generation efficiency by modulating the dipole moments of the building blocks in porous polymeric organic semiconductors.

Insertion of pillar[5]arene into Troger’s base-derived porous organic polymer for promoted heterogeneous catalytic performance in Knoevenagel condensation and CO_(2)fixation

Development of new metal-free heterogeneous catalysts has long been the focus of intense research interest.The integration of multifunctional monomers into the skeletons of porous organic polymers(POPs)provides an efficient pathway to achieve this goal.Herein,we rationally designed and successfully prepared a new Troger’s base(TB)-derived POPs by insertion of pillar[5]arene macrocycle as a positively auxiliary group.Combined the both merits of pillar[5]arene macrocycle and TB moiety,the as-prepared polymer was further explored as an effective metal-free heterogeneous catalyst and exhibited promoted catalytic performance in Knoevenagel condensation and CO_(2)conversion.This work provides a new strategy to fabricate metal-free heterogeneous catalysts based on macrocyclic POPs.

Controlled Synthesis of Proton-Conductive Porous Organic Polymer Gels via Electrostatically Stabilized Colloidal Formation

Porous organic polymers(POPs)have attracted extensive interest due to their structural diversity and predesigned functionality.However,the majority of POPs are synthesized as insoluble and unprocessable powders,which greatly impede their advanced applications because of limited mass transport and inadaptation for device integration.Herein,we report a controlled synthetic strategy of macroscopic POP gels by a cation-stabilized colloidal formation mechanism,which is widely adaptable to a large variety of tetra-/tri-amino build blocks for the synthesis of Tröger’s base-linked POP gels,aerogels,and ionic gels.The POP gels combined the integrated advantages of hierarchically porous structures and tailorable mechanical stiffness,whereas they could load substantial amounts of phosphoric acids and construct unimpeded transport pathways for proton conduction,exhibiting unprecedented proton conductivity at subzero temperatures.Our strategy offers a new solution to the intractable processing issues of POPs toward device applications with cutting-edge performances.

Electron donor–acceptor (D-A) tuning to achieve soluble covalent organic polymers for optoelectronic devices

Covalent organic polymers(COPs)have emerged as a unique class of luminescent polymers with pre-designed quasi-ordered architectures.However,their layered stacks and limited solubility preclude further processing for large-scale applications in devices,especially optoelectronic equipment.Herein,a universal strategy to adjust the electron donor–acceptor(D-A)moieties of the building blocks in COPs is proposed,achieved by in situ charge exfoliation of COP blocks into few-layer true solutions in(Lewis)acid and base media.The electron D-A moieties of the building blocks endow the COPs with the ability to accept or donate electrons,by altering the electron cloud distribution as well as the relative energy levels of the frontier molecular orbitals.The resultant soluble COPs can easily be processed into a uniform film by solution processing via the spin-coat method.The obtained COP-N achieves efficient and stable perovskite electroluminescence as a novel hole injection material on indium tin oxide,and the operating lifetime for a perovskite quantum dot light-emitting diodes device exceeds that of a poly(ethylene dioxythiophene):polystyrene sulphonate counterpart.This straightforward electronic regulation strategy provides a new avenue for the rational synthesis of processable reticular molecular polymers for practical electronic devices.

Repairable,Recyclable,and Regenerable Macrocycle Organic Polymer

Covalent/metal organic frameworks are highly attractive due to their tunable structure and properties,and broad applications in multiple fields.However,they still suffer from numbers of drawbacks including low solubility,harsh synthesis and fabrication,and low mechanical flexibility.Herein,we report a new organic framework consisting of macrocycles and organic frames in its periodic structure,and denote it as macrocycle organic polymer(MOP).The size-tunable macrocycles containing peripheral furan units are synthesized by anionic ring-opening polymerization,which undergo a reversible Diels-Alde reaction with bismaleimide to generate/degrade MOPs at given temperatures.Relying on above features,MOPs exhibit excellent flexibility,healable ability and recycle ability.Interestingly,owing to the“living”nature of anionic ring-opening polymerization,MOPs can self-grow into bigger sizes in the presence of monomer and catalysis,analogs to the living creatures.Moreover,their high porosity and rich thioether structure enable them as good metal ion absorbers and promising applications in wearable electronics.

Pyrylium-based porous organic polymers via Knoevenagel condensation for efficient visible-light-driven heterogeneous photodegradation

Pyrylium salts are a type of representative and convincing example of versatility and variety not only as a nodal point in organic transformations but also as an attractive building block in functional organic materials. Herein, we report an effective synthetic protocol to fabricate a new pyrylium-containing porous organic polymers(POPs), named TMP-P, via Knoevenagel condensation with 2,4,6-trimethylpyrylium salt(TMP) as the key building block and 1,4-phthalaldehyde as the linker. The resulting ionic polymer TMPP exhibited efficient visible-light-driven heterogeneous photodegradation of Rhodamine B, owing to the presence of wide visible light absorption and a narrow optical band gap triggered pyrylium core in the framework.

Hollow tubular conjugated organic polymer for lithium batteries

Polymerization is a valid strategy to solve the dissolution issue of organic electrode materials in aprotic electrolytes.However,conventional polymers usually with amorphous structures and morphology’s influence on electrochemistry have rarely been studied.Herein,a hollow tubular poly phenyl pyrene-4,5,9,10-tetraone(T-PPh-PTO)organic cathode material was designed and synthesized based on the concentration-gradient of the precursor(PTO-Br2)and asymmetrical internal diffusion during the reaction.The unique hollow structure endowed T-PPh-PTO with a short Li+diffusion path accompanied by a high diffusion Li+coefficient(D≈10−8 cm^(2)·s^(−1)).Thus,T-PPh-PTO presented a capacitance-dominated redox pseudocapacitance action with an outstanding rate performance(173 mAh·g^(−1)at 2 A·g^(−1))and high cycle stability(capacity retention ratio is 91.7%after 2,000 cycles).Our study leads to further developments in designing unique organic structures for energy storage.

Temporally Separated CO_(2) Photoreduction and H_(2)O Photooxidation over Redox-Active Conjugated Organic Polymer Films

Photocatalytic CO_(2) reduction with H_(2)O of chemicals without H2 generation is interesting but challenging.Herein,we report temporally separated CO_(2) photoreduction and H_(2)O photooxidation that are achieved over redox-active o-hydroxyazo-based conjugated organic polymer films(HAzo-COPFs),affording CO with high efficiency as the sole reduction product.HAzo-COPFs are prepared via interfacial diazo-coupling reactions of aromatic diamines and diphenols,and HAzo-COPF-1 from 4,4′-biphenol and benzidine shows the best performance with a CO generation rate of 53.6μmol g−1 h−1 under visible-light irradiation(>420 nm).Interestingly,we discovered that diphenol(DP-OH)moieties in HAzo-COPFs,serving as electron and proton donors to participate in CO_(2) photoreduction,are oxidized into quinone(DP=O)moieties,which are subsequently photoreduced to regenerate DP-OH in H_(2)O photooxidation.Consequently,CO_(2) photoreduction and H_(2)O photooxidation are temporally separated and perfectly coupled via redox transformation between DP-OH and DP=O that form in situ,affording enhanced charge carrier separation and inhibiting the hydrogen evolution reaction.This work provides new insights for the design of COP photocatalysts and artificial photosynthesis.

(Catecholate)Cu^(I)_(2)-Displayed Porous Organic Polymers as Efficient Heterogeneous Catalysts for the Mild and Selective Aerobic Oxidation of Alcohols

Porous organic polymers(POPs)containing catalytically active sites are of paramount importance for heterogeneous catalysis.However,the catalytically active sites of reported POPs are mostly limited to mononuclear metal species.Herein,we report the reaction between catechol-containing POPs(Cat-POPs)and[CuIMes]n to afford the corresponding Cu^(I)_(2)-CatPOPs with a putative vicinal binuclear(catecholate)Cu^(I)_(2)moiety.The resulting Cu^(I)_(2)-CatPOPs exhibit high Brunauer–Emmett–Teller surface areas,good stability,and excellent catalytic activity toward the aerobic oxidation of a broad range of primary and secondary alcohols under mild conditions,with either 2,2,6,6-tetramethylpiperidinyl-N-oxyl or 9-azabicyclo[3.3.0]nonane-N-oxyl as the cocatalyst.As green aerobic oxidation catalysts,the Cu^(I)_(2)-CatPOPs are much more active than the correspondingmononuclear CuIICatPOPs,where each catecholate moiety only supports one CuII center;CuI-ConPOPs,where the binding sites for CuI is a nonvicinal 1,4-dihydroxybenzene moiety;and the homogeneous analogue(3,6-di-tert-butyl catecholate)Cu^(I)_(2).These results are consistent with a proposed vicinal binuclear Cu^(I)_(2)structure that can efficiently activate molecular oxygen for the aerobic oxidation of alcohols,mechanistically similar to that observed in dicopper-containing oxygenases.Our results demonstrate the facile preparation of POPs with binuclear catalytically active sites that function as green heterogeneous catalysts for efficient oxidation of alcohols.

Engineering porous organic polymers for carbon dioxide capture

As atmospheric CO_2 levels rise, the development of physical or chemical adsorbents for CO_2 capture and separation is of great importance on the way towards a sustainable low-carbon future. Porous organic polymers are promising candidates for CO_2 capture materials owing to their structural flexibility, high surface area, and high stability. In this review, we highlight high-performance porous organic polymers for CO_2 capture and summarize the strategies to enhance CO_2 uptake and selectivity, such as increasing surface area, increasing interaction between porous organic polymers and CO_2, and pore surface functionalization.

Potential applications of porous organic polymers as adsorbent for the adsorption of volatile organic compounds

Volatile organic compounds(VOCs)with high toxicity and carcinogenicity are emitted from kinds of industries,which endanger human health and the environment.Adsorption is a promising method for the treatment of VOCs due to its low cost and high efficiency.In recent years,activated carbons,zeolites,and mesoporous materials are widely used to remove VOCs because of their high specific surface area and abundant porosity.However,the hydrophilic nature and low desorption rate of those materials limit their commercial application.Furthermore,the adsorption capacities of VOCs still need to be improved.Porous organic polymers(POPs)with extremely high porosity,structural diversity,and hydrophobic have been considered as one of the most promising candidates for VOCs adsorption.This review generalized the superiority of POPs for VOCs adsorption compared to other porous materials and summarized the studies of VOCs adsorption on different types of POPs.Moreover,the mechanism of competitive adsorption between water and VOCs on the POPs was discussed.Finally,a concise outlook for utilizing POPs for VOCs adsorption was discussed,noting areas in which further work is needed to develop the next-generation POPs for practical applications.