Owing to the significant development in graphene,an increasing number of studies have been conducted to identify novel two-dimensional(2D)organic materials with Dirac cones and topological properties.Although a series...Owing to the significant development in graphene,an increasing number of studies have been conducted to identify novel two-dimensional(2D)organic materials with Dirac cones and topological properties.Although a series of toy models based on specific lattice patterns has been proposed and demonstrated to possess a Dirac cone,realistic materials corresponding to the lattice models must be identified to achieve excellent properties for practical applications.To understand factors contributing to the rarity of 2D organic Dirac materials and provide guidance for identifying novel organic Dirac systems,we review recent theoretical studies pertaining to various 2D Dirac models and their corresponding organic Dirac materials,including the Haldane,Kagome,Libe,linecentered honeycomb,and Cairo pentagonal models.Subsequently,the corresponding structural and topological electronic properties are summarized.Additionally,we investigate the relationship between the existence of Dirac cones and their structural features,as well as the manner by which Dirac points emerge and propagate in these systems.展开更多
Rationally designed multiporphyrinic architectures for boosting photodynamic therapy(PDT)have attracted significant attentions recently years due to their great potential for light-mediated generation of reactive oxyg...Rationally designed multiporphyrinic architectures for boosting photodynamic therapy(PDT)have attracted significant attentions recently years due to their great potential for light-mediated generation of reactive oxygen species.However,there is still a gap between the structure design and their PDT performance for biomedical applications.This tutorial review provides a historical overview on(i)the basic concept of PDT for deeply understanding the porphyrin-mediated PDT reactions,(ii)developing strategies for constructing porphyrinic architectures,like nanorings,boxes,metal-organic frameworks(MOFs),covalent-organic frameworks(COFs),vesicles,etc.,where we classified into the following three categories:multiporphyrin arrays,porphyrinic frameworks,and others porphyrin assemblies,(iii)the various application scenarios for clinical cancer therapy and antibacterial infection.Also,the existing challenges and future perspectives on the innovation of porphyrinic architectures for clinical PDT applications are mentioned in the end section.Moreover,the porphyrinic nanomaterials with atomically precise architectures provide an ideal platform for investigating the relationship between structures and PDT outputs,design of personalized“all-in-one”theranostic agents,and the popularization and application in wider biomedical fields.展开更多
The electrochemical carbon dioxide reduction reaction(CO_(2)RR)for highvalue-added products is a promising strategy to tackle excessive CO_(2) emissions.However,the activity of and selectivity for catalysts for CO_(2)...The electrochemical carbon dioxide reduction reaction(CO_(2)RR)for highvalue-added products is a promising strategy to tackle excessive CO_(2) emissions.However,the activity of and selectivity for catalysts for CO_(2)RR still need to be improved because of the competing reaction(hydrogen evolution reaction).In this study,for the first time,we have demonstrated dual atomic catalytic sites for CO_(2)RR from a core-shell hybrid of the covalent-organic framework and the metal-organic framework.Due to abundant dual atomic sites(with CoN_(4)O and ZnN_(4) of 2.47 and 11.05 wt.%,respectively)on hollow carbon,the catalyst promoted catalysis of CO_(2)RR,with the highest Faradic efficiency for CO of 92.6%at-0.8 V and a turnover frequency value of 1370.24 h^(-1) at-1.0 V.More importantly,the activity and selectivity of the catalyst were well retained for 30 h.The theoretical calculation further revealed that CoN_(4)O was the main site for CO_(2)RR,and the activity of and selectivity for Zn sites were also improved because of the synergetic roles.展开更多
Recently, covalent-organic polymers （COPs）, which covalently cross-link different types of organic molecules to form organic network structures, have received significant attention in various fields. However, the de...Recently, covalent-organic polymers （COPs）, which covalently cross-link different types of organic molecules to form organic network structures, have received significant attention in various fields. However, the design of COPs that allows them to act as therapeutic agents remains to be explored. In the present study, a new class of COPs was fabricated by cross-linking the photosensitizer meso-tetra（p-hydroxyphenyl） porphine （THPP） to a chemotherapeutic pro-drug, cis-platinum （IV）; the latter also acts as a reduction-responsive linker. After further conjugation with polyethylene glycol （PEG） in this one-pot reaction, we obtained THPP-Pt-PEG COPs, which can be stored in a lyophilized form and occur as stable nanoparticles in aqueous solution. The THPP-Pt-PEG COPs are effective in killing cancer cells through photodynamic treatment, and exhibited reduction-responsive degradation/drug release behaviors. Upon intravenous injection, the COPs, with a long blood circulation time, showed efficient tumor accumulation. Interestingly, we revealed that after injection of THPP-Pt-PEG COPs, tumors on mice exhibited greatly improved vascular perfusion and largely relieved tumor hypoxia, which favored subsequent photodynamic treatment. Hence, the combined chemo-photodynamic therapy of the COPs offers a remarkably improved therapeutic outcome compared to that with mono-therapies. This work presents a COP-based nanomedicine with high drug loading, lyophilizable formulation, prolonged blood half-life, efficient tumor passive homing, inherent biodegradability, and multiple therapeutic functions to achieve enhanced cancer combination therapy, with promise for clinical translation.展开更多
To attain the objectives of carbon peaking and carbon neutrality,the development of stable and highperformance ion-conducting materials holds enormous relevance in various energy storage and conversion devices.Particu...To attain the objectives of carbon peaking and carbon neutrality,the development of stable and highperformance ion-conducting materials holds enormous relevance in various energy storage and conversion devices.Particularly,crystalline porous materials possessing built-in ordered nanochannels exhibit remarkable superiority in comprehending the ion transfer mechanisms with precision.In this regard,covalent organic frameworks(COFs)are highly regarded as a promising alternative due to their preeminent structural tunability,accessible well-defined pores,and excellent thermal/chemical stability under hydrous/anhydrous conditions.By the availability of organic units and the diversity of topologies and connections,advances in COFs have been increasing rapidly over the last decade and they have emerged as a new field of proton-conducting materials.Therefore,a comprehensive summary and discussion are urgently needed to provide an"at a glance"understanding of the prospects and challenges in the development of proton-conducting COFs.In this review,we target a comprehensive review of COFs in the field of proton conductivity from the aspects of design strategies,the proton conducting mechanism/features,the relationships of structure-function,and the application of research.The relevant content of theoretical simulation,advanced structural characterizations,prospects,and challenges are also presented elaborately and critically.More importantly,we sincerely hope that this progress report will form a consistent view of this field and provide inspiration for future research.展开更多
We systematically investigate dynamic separation of Xe and Kr at room temperature using four representative porous materials(Cu-BTC, ZIF-8, COP-4 and activated carbon(AC)). Results indicate that among the four materia...We systematically investigate dynamic separation of Xe and Kr at room temperature using four representative porous materials(Cu-BTC, ZIF-8, COP-4 and activated carbon(AC)). Results indicate that among the four materials, Cu-BTC not only shows the highest retention volume per gram(V_g=788 m L g^(-1), which is 1.8 times of activated carbon(436 m L g^(-1))) under flowing condition, but also can separate 350 ppm Xe from 35 ppm Kr mixture in air with a high Xe/Kr selectivity of 8.6 at room temperature and 200 k Pa, due to its suitable pore morphology, open metal sites, small side pockets in the framework. Moreover, the Cu-BTC also performs well on individual separation of Xe, Kr, CO_2 from five-component gas mixture(Xe:Kr:CO_2:Ar:N_2= 1:1:1:1:0.5, V/V) and has the longest retention time for Xe(20 min) in gas chromatographic separation, suggesting that it is a good candidate for potential applications as polymeric sieves.展开更多
An imine-based nitrogen-rich covalent-organic framework(COF)was successfully synthesized using two tri-angular building units under solvothermal reaction condition.The gas adsorption properties of the obtained micro-p...An imine-based nitrogen-rich covalent-organic framework(COF)was successfully synthesized using two tri-angular building units under solvothermal reaction condition.The gas adsorption properties of the obtained micro-porous nitrogen-rich COF were investigated.The results indicated that the activated COF material presented good up take capabilities of CO_(2) and CH_(4) at 61.2 and 43.4 cm^(3)·g^(−1)at 1 atm and 273 K,respectively,showing its applica-tion potential in selective gas capture and separation.展开更多
Molecular hydrogen and spiltover hydrogen storages on five two-dimensional （2D） covalent-organic frameworks （COFs） （PPy-COF, TP-COF, BTP-COF, COF-18 A, and HHTP-DPB COF） are investigated using the grand canonica...Molecular hydrogen and spiltover hydrogen storages on five two-dimensional （2D） covalent-organic frameworks （COFs） （PPy-COF, TP-COF, BTP-COF, COF-18 A, and HHTP-DPB COF） are investigated using the grand canonical Monte Carlo （GCMC） simulations and the density functional theory （DFT）, respectively. The GCMC simulated results show that HHTP-DPB COF has the best performance for hydrogen storage, followed by BTP-COF, TP-COF, COF-18 A, and PPy-COE However, their adsorption amounts at room temperature are all too low to meet the uptake target set by US Department of Energy （US-DOE） and enable practical applications. The effects of pore size, surface area, and isosteric heat of hydrogen on adsorption amount are considered, which indicate that these three factors are all the important factors for determining the H2 adsorption amount. The chemisorptions of spiltover hydrogen atoms on these five COFs represented by the cluster models are investigated using the DFT method. The saturation cluster models are constructed by considering all possible adsorption sites for these cluster models. The average binding energy of a hydrogen atom and the saturation hydrogen storage density are calculated. The large average binding energy indicates that the spillover process may pro- ceed smoothly and reversibly. The saturation hydrogen storage density is much larger than the physisorption uptake of H2 molecules at 298 K and 100 bar （1 bar = 105 Pa）, and is close to or exceeds the 2010 US-DOE target of 6 wt% for hydrogen storage. This suggests that the hydrogen storage capacities of these COFs by spillover may be significantly enhanced. Thus 2D COFs studied in this paper are suitable hydrogen storage media by spillover.展开更多
Two-dimensional(2D)metal/covalent organic framework(MOF/COF)materials have ultra-thin thickness and large surface area.These advantages bestow them the characteristics of low resistance and high flux in the process of...Two-dimensional(2D)metal/covalent organic framework(MOF/COF)materials have ultra-thin thickness and large surface area.These advantages bestow them the characteristics of low resistance and high flux in the process of material transportation.Meanwhile,more active sites promote their application in the fields of catalysis and sensing.Recently,2D MOF/COF materials usher in a new wave of research.It is necessary to summarize the latest developments in this field in a timely and systematic manner and clarify future trends.In this review,we firstly introduce the advantages of 2D MOF/COF materials in hetero-porous structure and functional modification.Then,we discuss advanced strategies for preparing 2D MOF/COF materi-als,such as in-situ growth,interface synthesis,exfoliation method,electrochemical method,surfactant-assisted synthesis,and laminated assembly of MOF/COF nanosheets.Finally,we summarize the applications of 2D MOF/COF materials in membrane separation,sensors,and energy storage.In ad-dition,we discuss some unresolved scientific and technological challenges related to the future prospects of this field.展开更多
Hydrogen spillover mechanism of metal-supported covalent-organic frameworks COF-105 is investigated by means of the density functional theory, and the effects of metal catalysts M_4（Pt_4, Pd_4, and Ni_4） on the whol...Hydrogen spillover mechanism of metal-supported covalent-organic frameworks COF-105 is investigated by means of the density functional theory, and the effects of metal catalysts M_4（Pt_4, Pd_4, and Ni_4） on the whole spillover process are systematically analyzed. These three metal catalysts exhibit several similar phenomena：（i） they prefer to deposit on the tetra（_4-dihydroxyborylphenyl） silane（TBPS） cluster with surface-contacted configuration;（ii） only the H atoms at the bridge site can migrate to 2,3,6,7,10,11-hexahydroxy triphenylene（HHTP） and TBPS surfaces, and the migration process is an endothermic reaction and not stable;（iii） the introduction of M_4 catalyst can greatly reduce the diffusion energy barrier of H atoms, which makes it easier for the H atoms to diffuse on the substrate surface. Differently, all of the H2 molecules spontaneously dissociate into H atoms onto Pt_4 and Pd_4clusters. However, the adsorbed H2 molecules on Ni_4 cluster show two types of adsorption states： one activated state with stretched H–H bond length of 0.88 ？A via the Kubas interaction and five dissociated states with separated hydrogen atoms. Among all the M_4 catalysts, the orders of the binding energy of M_4 deposited on the substrate and average chemisorption energy per H2 molecule are Pt_4〉Ni_4〉Pd_4. On the contrary, the orders of the migration and diffusion barriers of H atoms are Pt_4展开更多
Sulfur hexafluoride(SF_(6))is an extremely severe greenhouse gas.It is an urgently important mission to find excellent candidates for selective adsorption of SF_(6),in order to reduce the emission of SF_(6) facilities...Sulfur hexafluoride(SF_(6))is an extremely severe greenhouse gas.It is an urgently important mission to find excellent candidates for selective adsorption of SF_(6),in order to reduce the emission of SF_(6) facilities.Here,we adopt the molecular simulation method to systematically explore the selective adsorption of SF_(6) in 22 kinds of representative covalent-and metal-organic frameworks.Results indicate that COF-6 is a promising candidate for the SF_(6) adsorption at low pressure P<20 kPa because of its small pore size,while MOF-180 and PAF-302 are excellent candidates at high pressure P=2×10^(3) kPa due to their large Brunauer-Emmett-Teller specific surface area(BET SSA)and pore volumes.For the two cases of the power industry(X_(SF_(6))=0.1)and the semiconductor industry(X_(SF_(6))=0.002)environments,COF-6 and ZIF-8 are fairly promising candidates for selective adsorption of SF_(6) from the SF_(6)/N_(2) mixtures,because they not only present the high selectivity,but also the large adsorption capacity at ambient environment,which can be considered as potential adsorbents for selective adsorption of SF_(6) at ambient conditions.展开更多
Porous materials play an important role in chemical catalysis,separation and other industrial applications.High-efficiency preparation of porous materials has become an active research area.Conventional synthesis of p...Porous materials play an important role in chemical catalysis,separation and other industrial applications.High-efficiency preparation of porous materials has become an active research area.Conventional synthesis of porous materials has been dominated by one-pot solution processing conditions carried out by bulk mixing under conventional electric heating via hydrothermal,solvothermal or ionothermal reactions where high temperatures and pressures are the standard.Continuous flow synthesis has many key advantages in terms of efficient mass and heat transfer,precise control of residence times,improved opportunities for automation and feedback control of synthesis,scaling-up reactions and improved safety parameters compared to above mentioned conventional batch scale synthetic methods.In this review,continuous flow synthesis of various crystalline porous materials such as metal-organic frameworks(MOFs),covalent-organic frameworks(COFs),porous organic cages and zeolites is discussed.Combination of microfluidic methods with other techniques are also shown including various heating ways and various methods of substrate adding.展开更多
Photocatalytic oxidation of organic molecules into highly value-added products is an innovative and challenging research which has gradually attracted remarkable attention of scientists.In this work,it is demonstrated...Photocatalytic oxidation of organic molecules into highly value-added products is an innovative and challenging research which has gradually attracted remarkable attention of scientists.In this work,it is demonstrated that the COF-TpPa with keto-enol tautomerism equilibrium structure shows excellent performance(yield>99%after 8 h)in the selective photocatalytic oxidative coupling of amines to imines under visible light irradiation.It is revealed that three kinds of reactive oxygen species(superoxide radical,hydroxyl radical and singlet oxygen)participate in this photocatalytic oxidation reaction.In addition,hydrogen protons cleaved from the benzyl are proven to be reduced to hydrogen in the conduction band of COF-TpPa in anaerobic atmosphere,accompanied with the formation of imines.The direct hydrogen evolution from amine provides an effective way to extract clean energy from organic molecule as well as the production of value-added chemicals.As a contrast,COF-LZU1 with similar structure and chemical composition to COF-TpPa but without keto-enol tautomerism exhibits worse optical properties and photocatalytic performance.It is also demonstrated that keto-enol tautomerism favors the adsorption of benzylamine based on the characterization results and theoretical calculations.展开更多
Metal-air batteries(MABs)have attracted considerable attention as a novel energy technology that can alleviate the severe energy crisis and environmental pollution.Two primary processes,including oxygen reduction reac...Metal-air batteries(MABs)have attracted considerable attention as a novel energy technology that can alleviate the severe energy crisis and environmental pollution.Two primary processes,including oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)occur on the air cathode and dominate the battery performance during battery charging and discharging.Recently,metal-organic frameworks(MOFs)and covalent-organic frameworks(COFs)emerge as promising cathode catalysts due to their structure and composition superiority.The unique characteristics of MOFs and COFs contribute to improved performance.This review mainly summarizes the recent applications of MOFs and COFs in a series of MABs,mainly including lithium-and zinc-air batteries.Additionally,some critical issues are emphasized regarding MOFs and COFs used in other MABs limited progress,their fabrication and alternatives to potential problems.展开更多
Metal-organic frameworks(MOFs)and covalent organic frameworks(COFs)with highly ordered porous structure,tunable bandgap,large specific surface area and structural diversity,provide an appealing platform for the develo...Metal-organic frameworks(MOFs)and covalent organic frameworks(COFs)with highly ordered porous structure,tunable bandgap,large specific surface area and structural diversity,provide an appealing platform for the development of stimulus response,sensing,imaging and optoelectronics.Among various tuning methods,pressure engineering using the diamond anvil cell is a highly powerful in-situ technique,which can efficiently modulate the structural and optical properties of MOFs/COFs.This is beyond the realization of traditional chemical methods.This review outlines the research progress in the experimentoriented discovery of new phases or unique properties under high pressure,including phase transition,abnormal compression,photoluminescence(PL)discoloration and enhancement.Notably,the improvement of PL quantum yield in MOFs could be achieved by pressure-treated engineering and hydrogen-bonding cooperativity effect.We also propose and establish the relationship between structure and optical properties under high pressure.Finally,the challenge and outlook of the current fields are summarized.We hope that this review will supply guidance for comprehending the development of high-pressure MOF/COF-related research fields,and offer novel strategies for designing more high-performance MOF/COF materials to ultimately expand their applications.展开更多
基金the Natural Science Foundation of Shandong Province(No.ZR2021YQ04)Peng is grateful for the project funded by the China Postdoctoral Science Foundation(No.2022M712141)N.Ren acknowledges support from the National Natural Science Foundation of China(No.51972148)。
文摘Owing to the significant development in graphene,an increasing number of studies have been conducted to identify novel two-dimensional(2D)organic materials with Dirac cones and topological properties.Although a series of toy models based on specific lattice patterns has been proposed and demonstrated to possess a Dirac cone,realistic materials corresponding to the lattice models must be identified to achieve excellent properties for practical applications.To understand factors contributing to the rarity of 2D organic Dirac materials and provide guidance for identifying novel organic Dirac systems,we review recent theoretical studies pertaining to various 2D Dirac models and their corresponding organic Dirac materials,including the Haldane,Kagome,Libe,linecentered honeycomb,and Cairo pentagonal models.Subsequently,the corresponding structural and topological electronic properties are summarized.Additionally,we investigate the relationship between the existence of Dirac cones and their structural features,as well as the manner by which Dirac points emerge and propagate in these systems.
基金National Key R&D Program of China,Grant/Award Number:2020YFA0908500National Natural Science Foundation of China,Grant/Award Numbers:22371062,22001054,22075065,22275046+1 种基金Zhejiang Provincial Natural Science Foundation,Grant/Award Number:LY23E030001Hangzhou Leading Innovation and Entrepreneurship Team Project,Grant/Award Number:TD2022001。
文摘Rationally designed multiporphyrinic architectures for boosting photodynamic therapy(PDT)have attracted significant attentions recently years due to their great potential for light-mediated generation of reactive oxygen species.However,there is still a gap between the structure design and their PDT performance for biomedical applications.This tutorial review provides a historical overview on(i)the basic concept of PDT for deeply understanding the porphyrin-mediated PDT reactions,(ii)developing strategies for constructing porphyrinic architectures,like nanorings,boxes,metal-organic frameworks(MOFs),covalent-organic frameworks(COFs),vesicles,etc.,where we classified into the following three categories:multiporphyrin arrays,porphyrinic frameworks,and others porphyrin assemblies,(iii)the various application scenarios for clinical cancer therapy and antibacterial infection.Also,the existing challenges and future perspectives on the innovation of porphyrinic architectures for clinical PDT applications are mentioned in the end section.Moreover,the porphyrinic nanomaterials with atomically precise architectures provide an ideal platform for investigating the relationship between structures and PDT outputs,design of personalized“all-in-one”theranostic agents,and the popularization and application in wider biomedical fields.
基金Q.Xu acknowledges financial support from the Natural Science Foundation of Shanghai(20ZR1464000)G.Zeng is grateful for the support from the National Natural Science Foundation of China(21878322,22075309)the Science and Technology Commission of Shanghai(19ZR1479200).The authors also thank the Shanghai Synchrotron Radiation Facility for XAFS measurements at Beamline BL14w1.
文摘The electrochemical carbon dioxide reduction reaction(CO_(2)RR)for highvalue-added products is a promising strategy to tackle excessive CO_(2) emissions.However,the activity of and selectivity for catalysts for CO_(2)RR still need to be improved because of the competing reaction(hydrogen evolution reaction).In this study,for the first time,we have demonstrated dual atomic catalytic sites for CO_(2)RR from a core-shell hybrid of the covalent-organic framework and the metal-organic framework.Due to abundant dual atomic sites(with CoN_(4)O and ZnN_(4) of 2.47 and 11.05 wt.%,respectively)on hollow carbon,the catalyst promoted catalysis of CO_(2)RR,with the highest Faradic efficiency for CO of 92.6%at-0.8 V and a turnover frequency value of 1370.24 h^(-1) at-1.0 V.More importantly,the activity and selectivity of the catalyst were well retained for 30 h.The theoretical calculation further revealed that CoN_(4)O was the main site for CO_(2)RR,and the activity of and selectivity for Zn sites were also improved because of the synergetic roles.
文摘Recently, covalent-organic polymers （COPs）, which covalently cross-link different types of organic molecules to form organic network structures, have received significant attention in various fields. However, the design of COPs that allows them to act as therapeutic agents remains to be explored. In the present study, a new class of COPs was fabricated by cross-linking the photosensitizer meso-tetra（p-hydroxyphenyl） porphine （THPP） to a chemotherapeutic pro-drug, cis-platinum （IV）; the latter also acts as a reduction-responsive linker. After further conjugation with polyethylene glycol （PEG） in this one-pot reaction, we obtained THPP-Pt-PEG COPs, which can be stored in a lyophilized form and occur as stable nanoparticles in aqueous solution. The THPP-Pt-PEG COPs are effective in killing cancer cells through photodynamic treatment, and exhibited reduction-responsive degradation/drug release behaviors. Upon intravenous injection, the COPs, with a long blood circulation time, showed efficient tumor accumulation. Interestingly, we revealed that after injection of THPP-Pt-PEG COPs, tumors on mice exhibited greatly improved vascular perfusion and largely relieved tumor hypoxia, which favored subsequent photodynamic treatment. Hence, the combined chemo-photodynamic therapy of the COPs offers a remarkably improved therapeutic outcome compared to that with mono-therapies. This work presents a COP-based nanomedicine with high drug loading, lyophilizable formulation, prolonged blood half-life, efficient tumor passive homing, inherent biodegradability, and multiple therapeutic functions to achieve enhanced cancer combination therapy, with promise for clinical translation.
基金financial support from the National Natural Science Foundation of China(21978024)the Beijing Natural Science Foundation(2202034)。
文摘To attain the objectives of carbon peaking and carbon neutrality,the development of stable and highperformance ion-conducting materials holds enormous relevance in various energy storage and conversion devices.Particularly,crystalline porous materials possessing built-in ordered nanochannels exhibit remarkable superiority in comprehending the ion transfer mechanisms with precision.In this regard,covalent organic frameworks(COFs)are highly regarded as a promising alternative due to their preeminent structural tunability,accessible well-defined pores,and excellent thermal/chemical stability under hydrous/anhydrous conditions.By the availability of organic units and the diversity of topologies and connections,advances in COFs have been increasing rapidly over the last decade and they have emerged as a new field of proton-conducting materials.Therefore,a comprehensive summary and discussion are urgently needed to provide an"at a glance"understanding of the prospects and challenges in the development of proton-conducting COFs.In this review,we target a comprehensive review of COFs in the field of proton conductivity from the aspects of design strategies,the proton conducting mechanism/features,the relationships of structure-function,and the application of research.The relevant content of theoretical simulation,advanced structural characterizations,prospects,and challenges are also presented elaborately and critically.More importantly,we sincerely hope that this progress report will form a consistent view of this field and provide inspiration for future research.
基金supported by the “Radiochemistry 909 Program” in China Academy of Engineering Physics and the National Natural Science Foundation of China (91334203, 21274011)
文摘We systematically investigate dynamic separation of Xe and Kr at room temperature using four representative porous materials(Cu-BTC, ZIF-8, COP-4 and activated carbon(AC)). Results indicate that among the four materials, Cu-BTC not only shows the highest retention volume per gram(V_g=788 m L g^(-1), which is 1.8 times of activated carbon(436 m L g^(-1))) under flowing condition, but also can separate 350 ppm Xe from 35 ppm Kr mixture in air with a high Xe/Kr selectivity of 8.6 at room temperature and 200 k Pa, due to its suitable pore morphology, open metal sites, small side pockets in the framework. Moreover, the Cu-BTC also performs well on individual separation of Xe, Kr, CO_2 from five-component gas mixture(Xe:Kr:CO_2:Ar:N_2= 1:1:1:1:0.5, V/V) and has the longest retention time for Xe(20 min) in gas chromatographic separation, suggesting that it is a good candidate for potential applications as polymeric sieves.
基金supported by the National Research Foundation (NRF),Prime Minister’s Office,Singapore under its NRF Fellowship (NRF2009NRF-RF001-015)Campus for Research Excellence and Technological Enterprise (CREATE)Programme-Singapore Peking University Research Centre for a Sustainable Low-Carbon Futurethe NTU-A*Star Centre of Excellence for Silicon Technologies (A*Star SERC No.:1123510003).
文摘An imine-based nitrogen-rich covalent-organic framework(COF)was successfully synthesized using two tri-angular building units under solvothermal reaction condition.The gas adsorption properties of the obtained micro-porous nitrogen-rich COF were investigated.The results indicated that the activated COF material presented good up take capabilities of CO_(2) and CH_(4) at 61.2 and 43.4 cm^(3)·g^(−1)at 1 atm and 273 K,respectively,showing its applica-tion potential in selective gas capture and separation.
基金supported by the National Natural Science Foundation of China(Grant Nos.11247275 and 11304079)the Young Core Instructor of the Higher Education Institutions of Henan Province+1 种基金the Special Foundation for Fostering Technologic Innovative Talents of Henan University of Technology,China(Grant No.2012CXRC16)the Natural Science Foundation of Education Bureau of Henan Province,China(Grant Nos.2011B140005 and 13A140195)
文摘Molecular hydrogen and spiltover hydrogen storages on five two-dimensional （2D） covalent-organic frameworks （COFs） （PPy-COF, TP-COF, BTP-COF, COF-18 A, and HHTP-DPB COF） are investigated using the grand canonical Monte Carlo （GCMC） simulations and the density functional theory （DFT）, respectively. The GCMC simulated results show that HHTP-DPB COF has the best performance for hydrogen storage, followed by BTP-COF, TP-COF, COF-18 A, and PPy-COE However, their adsorption amounts at room temperature are all too low to meet the uptake target set by US Department of Energy （US-DOE） and enable practical applications. The effects of pore size, surface area, and isosteric heat of hydrogen on adsorption amount are considered, which indicate that these three factors are all the important factors for determining the H2 adsorption amount. The chemisorptions of spiltover hydrogen atoms on these five COFs represented by the cluster models are investigated using the DFT method. The saturation cluster models are constructed by considering all possible adsorption sites for these cluster models. The average binding energy of a hydrogen atom and the saturation hydrogen storage density are calculated. The large average binding energy indicates that the spillover process may pro- ceed smoothly and reversibly. The saturation hydrogen storage density is much larger than the physisorption uptake of H2 molecules at 298 K and 100 bar （1 bar = 105 Pa）, and is close to or exceeds the 2010 US-DOE target of 6 wt% for hydrogen storage. This suggests that the hydrogen storage capacities of these COFs by spillover may be significantly enhanced. Thus 2D COFs studied in this paper are suitable hydrogen storage media by spillover.
基金This work was supported by the National Key R&D Program of China(2018YFA0703200)the National Natural Science Foundation of China(51773041,61890940)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB30000000)the Chongqing Bayu Scholar Program(DP2020036)and Fudan University.
文摘Two-dimensional(2D)metal/covalent organic framework(MOF/COF)materials have ultra-thin thickness and large surface area.These advantages bestow them the characteristics of low resistance and high flux in the process of material transportation.Meanwhile,more active sites promote their application in the fields of catalysis and sensing.Recently,2D MOF/COF materials usher in a new wave of research.It is necessary to summarize the latest developments in this field in a timely and systematic manner and clarify future trends.In this review,we firstly introduce the advantages of 2D MOF/COF materials in hetero-porous structure and functional modification.Then,we discuss advanced strategies for preparing 2D MOF/COF materi-als,such as in-situ growth,interface synthesis,exfoliation method,electrochemical method,surfactant-assisted synthesis,and laminated assembly of MOF/COF nanosheets.Finally,we summarize the applications of 2D MOF/COF materials in membrane separation,sensors,and energy storage.In ad-dition,we discuss some unresolved scientific and technological challenges related to the future prospects of this field.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11304079,11304140,11404094,and 11504088)the China National Scholarship Foundation(Grant No.201508410255)+4 种基金the Foundation for Young Core Teachers of Higher Education Institutions of Henan Province of Chinathe Foundation for Young Core Teachers of Henan University of Technology in Chinathe Korea Institute of Science and Technology(KIST)Institutional Program(Grant No.2E26291)Flag Program(Grant No.2E26300)the Research Grants of NRF funded by the National Research Foundation under the Ministry of Science,ICT&Future,Korea(Grant No.NRF-2015H1D3A1036078)
文摘Hydrogen spillover mechanism of metal-supported covalent-organic frameworks COF-105 is investigated by means of the density functional theory, and the effects of metal catalysts M_4（Pt_4, Pd_4, and Ni_4） on the whole spillover process are systematically analyzed. These three metal catalysts exhibit several similar phenomena：（i） they prefer to deposit on the tetra（_4-dihydroxyborylphenyl） silane（TBPS） cluster with surface-contacted configuration;（ii） only the H atoms at the bridge site can migrate to 2,3,6,7,10,11-hexahydroxy triphenylene（HHTP） and TBPS surfaces, and the migration process is an endothermic reaction and not stable;（iii） the introduction of M_4 catalyst can greatly reduce the diffusion energy barrier of H atoms, which makes it easier for the H atoms to diffuse on the substrate surface. Differently, all of the H2 molecules spontaneously dissociate into H atoms onto Pt_4 and Pd_4clusters. However, the adsorbed H2 molecules on Ni_4 cluster show two types of adsorption states： one activated state with stretched H–H bond length of 0.88 ？A via the Kubas interaction and five dissociated states with separated hydrogen atoms. Among all the M_4 catalysts, the orders of the binding energy of M_4 deposited on the substrate and average chemisorption energy per H2 molecule are Pt_4〉Ni_4〉Pd_4. On the contrary, the orders of the migration and diffusion barriers of H atoms are Pt_4
基金We are greatly thankful to the support from the Open Fund of the State Key Laboratory of Laser Interaction with Matter(SKLLIM1710).
文摘Sulfur hexafluoride(SF_(6))is an extremely severe greenhouse gas.It is an urgently important mission to find excellent candidates for selective adsorption of SF_(6),in order to reduce the emission of SF_(6) facilities.Here,we adopt the molecular simulation method to systematically explore the selective adsorption of SF_(6) in 22 kinds of representative covalent-and metal-organic frameworks.Results indicate that COF-6 is a promising candidate for the SF_(6) adsorption at low pressure P<20 kPa because of its small pore size,while MOF-180 and PAF-302 are excellent candidates at high pressure P=2×10^(3) kPa due to their large Brunauer-Emmett-Teller specific surface area(BET SSA)and pore volumes.For the two cases of the power industry(X_(SF_(6))=0.1)and the semiconductor industry(X_(SF_(6))=0.002)environments,COF-6 and ZIF-8 are fairly promising candidates for selective adsorption of SF_(6) from the SF_(6)/N_(2) mixtures,because they not only present the high selectivity,but also the large adsorption capacity at ambient environment,which can be considered as potential adsorbents for selective adsorption of SF_(6) at ambient conditions.
基金the National Natural Science Foundation of China(NSFC,No.51573216)the NSF of Guangdong Province for financial support。
文摘Porous materials play an important role in chemical catalysis,separation and other industrial applications.High-efficiency preparation of porous materials has become an active research area.Conventional synthesis of porous materials has been dominated by one-pot solution processing conditions carried out by bulk mixing under conventional electric heating via hydrothermal,solvothermal or ionothermal reactions where high temperatures and pressures are the standard.Continuous flow synthesis has many key advantages in terms of efficient mass and heat transfer,precise control of residence times,improved opportunities for automation and feedback control of synthesis,scaling-up reactions and improved safety parameters compared to above mentioned conventional batch scale synthetic methods.In this review,continuous flow synthesis of various crystalline porous materials such as metal-organic frameworks(MOFs),covalent-organic frameworks(COFs),porous organic cages and zeolites is discussed.Combination of microfluidic methods with other techniques are also shown including various heating ways and various methods of substrate adding.
基金supported by the National Natural Science Foundation of China (51802015, 51972024)the Fundamental Research Funds for the Central Universities (FRF-TP-20-005A3)the Interdisciplinary Research Project for Young Teachers of USTB (Fundamental Research Funds for the Central Universities) (FRF-IDRY-19-020)。
文摘Photocatalytic oxidation of organic molecules into highly value-added products is an innovative and challenging research which has gradually attracted remarkable attention of scientists.In this work,it is demonstrated that the COF-TpPa with keto-enol tautomerism equilibrium structure shows excellent performance(yield>99%after 8 h)in the selective photocatalytic oxidative coupling of amines to imines under visible light irradiation.It is revealed that three kinds of reactive oxygen species(superoxide radical,hydroxyl radical and singlet oxygen)participate in this photocatalytic oxidation reaction.In addition,hydrogen protons cleaved from the benzyl are proven to be reduced to hydrogen in the conduction band of COF-TpPa in anaerobic atmosphere,accompanied with the formation of imines.The direct hydrogen evolution from amine provides an effective way to extract clean energy from organic molecule as well as the production of value-added chemicals.As a contrast,COF-LZU1 with similar structure and chemical composition to COF-TpPa but without keto-enol tautomerism exhibits worse optical properties and photocatalytic performance.It is also demonstrated that keto-enol tautomerism favors the adsorption of benzylamine based on the characterization results and theoretical calculations.
基金supported by the National Natural Science Foundation of China(22035003 and 21905142)the Programme of Introducing Talents of Discipline to Universities(No.B18030)+2 种基金the Natural Science Fund of Tianjin(nos.19JCZDJC37200 and19JCQNJC02600)the Youth Scientific and Technical Plan Project of Gansu Province(20JR10RA198)the China Postdoctoral Science Foundation(2019M651008)。
文摘Metal-air batteries(MABs)have attracted considerable attention as a novel energy technology that can alleviate the severe energy crisis and environmental pollution.Two primary processes,including oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)occur on the air cathode and dominate the battery performance during battery charging and discharging.Recently,metal-organic frameworks(MOFs)and covalent-organic frameworks(COFs)emerge as promising cathode catalysts due to their structure and composition superiority.The unique characteristics of MOFs and COFs contribute to improved performance.This review mainly summarizes the recent applications of MOFs and COFs in a series of MABs,mainly including lithium-and zinc-air batteries.Additionally,some critical issues are emphasized regarding MOFs and COFs used in other MABs limited progress,their fabrication and alternatives to potential problems.
基金supported by the National Natural Science Foundation of China(12304261,12274177)。
文摘Metal-organic frameworks(MOFs)and covalent organic frameworks(COFs)with highly ordered porous structure,tunable bandgap,large specific surface area and structural diversity,provide an appealing platform for the development of stimulus response,sensing,imaging and optoelectronics.Among various tuning methods,pressure engineering using the diamond anvil cell is a highly powerful in-situ technique,which can efficiently modulate the structural and optical properties of MOFs/COFs.This is beyond the realization of traditional chemical methods.This review outlines the research progress in the experimentoriented discovery of new phases or unique properties under high pressure,including phase transition,abnormal compression,photoluminescence(PL)discoloration and enhancement.Notably,the improvement of PL quantum yield in MOFs could be achieved by pressure-treated engineering and hydrogen-bonding cooperativity effect.We also propose and establish the relationship between structure and optical properties under high pressure.Finally,the challenge and outlook of the current fields are summarized.We hope that this review will supply guidance for comprehending the development of high-pressure MOF/COF-related research fields,and offer novel strategies for designing more high-performance MOF/COF materials to ultimately expand their applications.
