Due to insufficient energy density,supercapacitors(SCs)with preeminent-power and long cycle stability cannot be implemented in some practical applications.Exploring hybrid materials with redox activity to emerge high ...Due to insufficient energy density,supercapacitors(SCs)with preeminent-power and long cycle stability cannot be implemented in some practical applications.Exploring hybrid materials with redox activity to emerge high specific capacitance in ionic liquid(IL)electrolytes can solve this problem.Herein,we report a redox-organic molecule 2,6-diaminoanthraquinone(DAAQ)modified MXene(Ti3C2Tx)/Graphene(DAAQ-M/G)composite material.With the assist of graphene oxide(GO),MXene and graphene fabricate a three-dimensional(3D)interconnected structure as a conductive framework,which inhibits self-stacking of MXene monolayers and ensures high electronic conductivity.Meanwhile,DAAQ is loaded onto the M/G framework through covalent/non-covalent functionalization.The DAAQ as a spacer effectively enlarges the interlayer spacing of MXene nanosheets,and meanwhile produces reversible redox reactions during charge/discharge processes to provide additional Faradaic contribution to capacity.Therefore,the specific capacitance(capacity)of the DAAQ-M/G as the negative electrode material reaches to 226 F g^(-1)(306 C g^(-1))at 1 A g^(-1)in 1-ethyl-3-methylimidazolium tetrafluoroborate(EmimBF4)electrolyte.Furthermore,an asymmetric supercapacitor(ASC)is assembled using DAAQ-M/G as the negative electrode and self-prepared organic molecule hydroquinone modified reduced graphene oxide(HQ-RGO)material as the positive electrode,with a high energy density of 43 Wh kg^(-1)at high power density of 1669 Wkg^(-1).The ASC can maintain 80%of initial specific capacitance after 9000 cycles.This research can provide better support to develop advanced organic molecules-modified MXene composite materials for ionic liquid-based SCs.展开更多
The asymmetric photocatalytic organic synthesis(APOS)process is a sustainable and environmentally benign method for the production of optically active chemicals with sunlight as an energy source.However,it still lacks...The asymmetric photocatalytic organic synthesis(APOS)process is a sustainable and environmentally benign method for the production of optically active chemicals with sunlight as an energy source.However,it still lacks efficient semiconductors with tunable band structures and has a low recycling stability.Herein,we report the synthesis of tetrahydroquinoline-linked covalent organic frameworks(QH-COFs)with irreversible tetrahydroquinoline linkage as efficient semiconductors for the visible-light-driven asymmetricα-alkylation of aldehydes by merging with a chiral secondary amine.Up to 94%ee was obtained over QH-COFs,and the activity of QH-COFs was significantly higher than those of inorganic semiconductors(e.g.,Ti O2,Bi VO4,and WO3)under similar conditions,which is mainly attributed to their narrow band gap and suitable band edge.As far as we know,QH-COFs are the most active semiconductors for asymmetricα-alkylation of aldehydes ever reported.The QH-COFs were prepared via a one-pot Povarov cascade imine formation and cycloaddition reaction using Sc(OTf)3/Yb(OTf)3 as Lewis acid catalysts.Attributed to the tetrahydroquinoline linkage,QH-COFs showed extremely high recycling stability,which made practicals application possible.This work not only opens up a new avenue for asymmetric photocatalysis but also provides an efficient and general method for the construction of robust COFs.展开更多
Carbon super-heterostructures with high nitrogen contents from the covalent hybrid precursors of covalent triazine frameworks(CTFs)and zeolitic imidazolic frameworks(ZIFs)are scarcely explored because of CTF's ord...Carbon super-heterostructures with high nitrogen contents from the covalent hybrid precursors of covalent triazine frameworks(CTFs)and zeolitic imidazolic frameworks(ZIFs)are scarcely explored because of CTF's ordered structure and toxic superacid that dissolves or destabilizes the metal nodes.To solve this problem,herein,we report a straightforward two-step pathway for the covalent hybridization of disordered CTF(d–CTF)–ZIF composites via preincorporation of an imidazole(IM)linker into ordered CTFs,followed by the imidazole-site-specific covalent growth of ZIFs.Direct carbonization of these synthesized d–CTF−IM−ZIF hybrids results in unique hollow carbon super-heterostructures with ultrahigh nitrogen content(>18.6%),high specific surface area(1663m^(2)g^(−1)),and beneficial trace metal(Co/Zn NPs)contents for promoting the redox pseudocapacitance.As proof of concept,the obtained carbon super-heterostructure(Co–Zn–NC_(SNH)–800)is used as a positive electrode in an asymmetric supercapacitor,demonstrating a remarkable energy density of 61Wh kg^(−1)and extraordinary cyclic stability of 97%retention after 30,000 cycles at the cell level.Our presynthetic modifications of CTF and their covalent hybridization with ZIF crystals pave the way toward new design strategies for synthesizing functional porous carbon materials for promising energy applications.展开更多
Covalent organic frameworks(COFs), covalently assembled from the condensation reactions of organic building blocks, are a fascinating class of functional porous materials with two-or three-dimensional crystalline orga...Covalent organic frameworks(COFs), covalently assembled from the condensation reactions of organic building blocks, are a fascinating class of functional porous materials with two-or three-dimensional crystalline organic structures. Generally, it is preferable to use symmetric and rigid building blocks to construct highly crystalline COFs with desired topology. On the other hand, the incorporation of chiral functional moieties in the building blocks would open up new applications such as asymmetric catalysis and chiral separation. This mini review highlights the principle strategies in the design and synthesis of chiral COFs. The interesting and potential applications of these chiral COFs for asymmetric catalysis and chiral separation are also summarized.This mini review aims to provide an up-to-date advancement of chiral COFs for asymmetric catalysis and chiral separation.展开更多
The optical active alkyne-bridged Mo-Co heterometal complexes are synthesized by the chiral phase transfer catalyst (N-benzylcinchorin chloride) induced metal exchange reaction. The complex is used as catalyst to prom...The optical active alkyne-bridged Mo-Co heterometal complexes are synthesized by the chiral phase transfer catalyst (N-benzylcinchorin chloride) induced metal exchange reaction. The complex is used as catalyst to promote the asymmetric addition of diethylzinc to benzaldehyde. The ee value of the product alcohol is 5.7%, which illustrates the asymmetric induction of the tetrahedral framework chirality in asymmetric catalysis reaction for the first time.展开更多
Metal-organic frameworks(MOFs)with porous crystal structures have attracted extensive attention in application of energy storage and conversion,owing to their regularity,porosity,large specific surface area,etc.In thi...Metal-organic frameworks(MOFs)with porous crystal structures have attracted extensive attention in application of energy storage and conversion,owing to their regularity,porosity,large specific surface area,etc.In this work,Co-MOF-74 microflower has been successfully prepared via a controllable solvent regulation strategy.Through modulating the polarity of the solvent,crystals grow in certain preferred orientation and Co-MOF-74 with various morphologies were obtained.Thereinto,the energy storage performance of Co-MOF-74 microflower was measured in both three-electrode system and asymmetric supercapacitor device(specific capacitance of 164.2 F/g at 0.5 A/g in the three-electrode system and 62.5 F/g at 1 A/g in the asymmetric supercapacitor device).This can be attributed to the preferred crystal orientation resulting in a regular and uniform microflower,which is of great significance to electronic interfacial exchange and ion transfer during electrochemical reactions.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22173028,21873026).
文摘Due to insufficient energy density,supercapacitors(SCs)with preeminent-power and long cycle stability cannot be implemented in some practical applications.Exploring hybrid materials with redox activity to emerge high specific capacitance in ionic liquid(IL)electrolytes can solve this problem.Herein,we report a redox-organic molecule 2,6-diaminoanthraquinone(DAAQ)modified MXene(Ti3C2Tx)/Graphene(DAAQ-M/G)composite material.With the assist of graphene oxide(GO),MXene and graphene fabricate a three-dimensional(3D)interconnected structure as a conductive framework,which inhibits self-stacking of MXene monolayers and ensures high electronic conductivity.Meanwhile,DAAQ is loaded onto the M/G framework through covalent/non-covalent functionalization.The DAAQ as a spacer effectively enlarges the interlayer spacing of MXene nanosheets,and meanwhile produces reversible redox reactions during charge/discharge processes to provide additional Faradaic contribution to capacity.Therefore,the specific capacitance(capacity)of the DAAQ-M/G as the negative electrode material reaches to 226 F g^(-1)(306 C g^(-1))at 1 A g^(-1)in 1-ethyl-3-methylimidazolium tetrafluoroborate(EmimBF4)electrolyte.Furthermore,an asymmetric supercapacitor(ASC)is assembled using DAAQ-M/G as the negative electrode and self-prepared organic molecule hydroquinone modified reduced graphene oxide(HQ-RGO)material as the positive electrode,with a high energy density of 43 Wh kg^(-1)at high power density of 1669 Wkg^(-1).The ASC can maintain 80%of initial specific capacitance after 9000 cycles.This research can provide better support to develop advanced organic molecules-modified MXene composite materials for ionic liquid-based SCs.
文摘The asymmetric photocatalytic organic synthesis(APOS)process is a sustainable and environmentally benign method for the production of optically active chemicals with sunlight as an energy source.However,it still lacks efficient semiconductors with tunable band structures and has a low recycling stability.Herein,we report the synthesis of tetrahydroquinoline-linked covalent organic frameworks(QH-COFs)with irreversible tetrahydroquinoline linkage as efficient semiconductors for the visible-light-driven asymmetricα-alkylation of aldehydes by merging with a chiral secondary amine.Up to 94%ee was obtained over QH-COFs,and the activity of QH-COFs was significantly higher than those of inorganic semiconductors(e.g.,Ti O2,Bi VO4,and WO3)under similar conditions,which is mainly attributed to their narrow band gap and suitable band edge.As far as we know,QH-COFs are the most active semiconductors for asymmetricα-alkylation of aldehydes ever reported.The QH-COFs were prepared via a one-pot Povarov cascade imine formation and cycloaddition reaction using Sc(OTf)3/Yb(OTf)3 as Lewis acid catalysts.Attributed to the tetrahydroquinoline linkage,QH-COFs showed extremely high recycling stability,which made practicals application possible.This work not only opens up a new avenue for asymmetric photocatalysis but also provides an efficient and general method for the construction of robust COFs.
基金Ministry of Trade,Industry&Energy of Korea,Grant/Award Number:RS‐2022‐00155717National Research Foundation of Korea,Grant/Award Numbers:2020H1D3A1A04081472,2022M3J1A1054323。
文摘Carbon super-heterostructures with high nitrogen contents from the covalent hybrid precursors of covalent triazine frameworks(CTFs)and zeolitic imidazolic frameworks(ZIFs)are scarcely explored because of CTF's ordered structure and toxic superacid that dissolves or destabilizes the metal nodes.To solve this problem,herein,we report a straightforward two-step pathway for the covalent hybridization of disordered CTF(d–CTF)–ZIF composites via preincorporation of an imidazole(IM)linker into ordered CTFs,followed by the imidazole-site-specific covalent growth of ZIFs.Direct carbonization of these synthesized d–CTF−IM−ZIF hybrids results in unique hollow carbon super-heterostructures with ultrahigh nitrogen content(>18.6%),high specific surface area(1663m^(2)g^(−1)),and beneficial trace metal(Co/Zn NPs)contents for promoting the redox pseudocapacitance.As proof of concept,the obtained carbon super-heterostructure(Co–Zn–NC_(SNH)–800)is used as a positive electrode in an asymmetric supercapacitor,demonstrating a remarkable energy density of 61Wh kg^(−1)and extraordinary cyclic stability of 97%retention after 30,000 cycles at the cell level.Our presynthetic modifications of CTF and their covalent hybridization with ZIF crystals pave the way toward new design strategies for synthesizing functional porous carbon materials for promising energy applications.
基金supported by the Singapore Academic Research Fund(RG112/15,RG19/16)
文摘Covalent organic frameworks(COFs), covalently assembled from the condensation reactions of organic building blocks, are a fascinating class of functional porous materials with two-or three-dimensional crystalline organic structures. Generally, it is preferable to use symmetric and rigid building blocks to construct highly crystalline COFs with desired topology. On the other hand, the incorporation of chiral functional moieties in the building blocks would open up new applications such as asymmetric catalysis and chiral separation. This mini review highlights the principle strategies in the design and synthesis of chiral COFs. The interesting and potential applications of these chiral COFs for asymmetric catalysis and chiral separation are also summarized.This mini review aims to provide an up-to-date advancement of chiral COFs for asymmetric catalysis and chiral separation.
基金supported by the National Natural Science Foundation of China(20932002,20733010)National Key Basic Research Program ofChina(973)(2006CB202504)Chinese Academy of Sciences Fund(KJCX2.YW.H16)~~
基金This work was supported by the National Natural Science Foundation of China (Grant No. 29871061).
文摘The optical active alkyne-bridged Mo-Co heterometal complexes are synthesized by the chiral phase transfer catalyst (N-benzylcinchorin chloride) induced metal exchange reaction. The complex is used as catalyst to promote the asymmetric addition of diethylzinc to benzaldehyde. The ee value of the product alcohol is 5.7%, which illustrates the asymmetric induction of the tetrahedral framework chirality in asymmetric catalysis reaction for the first time.
基金supported by the National Natural Science Foundation of China(Nos.U1904215,21671170,21673203)the Topnotch Academic Programs Project of Jiangsu Higher Education Institutions(TAPP)+2 种基金Changjiang scholars program of the Ministry of Education(No.Q2018270)Excellent doctoral dissertation of Yangzhou universityUndergraduate scientific research innovation projects in Jiangsu province(No.201911117036Z)。
文摘Metal-organic frameworks(MOFs)with porous crystal structures have attracted extensive attention in application of energy storage and conversion,owing to their regularity,porosity,large specific surface area,etc.In this work,Co-MOF-74 microflower has been successfully prepared via a controllable solvent regulation strategy.Through modulating the polarity of the solvent,crystals grow in certain preferred orientation and Co-MOF-74 with various morphologies were obtained.Thereinto,the energy storage performance of Co-MOF-74 microflower was measured in both three-electrode system and asymmetric supercapacitor device(specific capacitance of 164.2 F/g at 0.5 A/g in the three-electrode system and 62.5 F/g at 1 A/g in the asymmetric supercapacitor device).This can be attributed to the preferred crystal orientation resulting in a regular and uniform microflower,which is of great significance to electronic interfacial exchange and ion transfer during electrochemical reactions.
