High piezoelectric composite films composed of poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)and ferromagnetic cobalt ferrite(CoFe_(2)O_(4))(0.00 wt%to 0.2 wt%)are prepared by a solution casting method acc...High piezoelectric composite films composed of poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)and ferromagnetic cobalt ferrite(CoFe_(2)O_(4))(0.00 wt%to 0.2 wt%)are prepared by a solution casting method accompanied by uniaxial stretching and high electric field poling.The decisive effect of the poling electric field on the power generating capability was confirmed by the experiments.For pure PVDF-HFP films,when the maximum electric field Emax is 120 MV/m,the calibrated open circuit voltage reaches 2.93 V,which is much higher than those poled at lower electric fields(70 MV/m:1.41 V;90 MV/m:2.11 V).Furthermore,the addition of CoFe_(2)O_(4)also influences the piezoelectricity dramatically.In the samples containing 0.15 wt%CoFe_(2)O_(4),the calibrated open circuit voltage increases to the maximum value of 3.57 V.Meanwhile,the relative fraction of theβ-phase and the crystallinity degree are 99%and 48%,respectively.The effects of CoFe_(2)O_(4)nanoparticles on initial crystallization,uniaxial stretching and high electric field poling are investigated by XRD,FTIR and DSC.展开更多
2025年1月9日,天津大学姜忠义教授团队在Angewandte Chemie International Edition期刊发表题为“Confining Phosphoric Acid in Quaternized COF Channels for Ultra-stable and Fast Anhydrous Proton Transport”的研究论文,团队成...2025年1月9日,天津大学姜忠义教授团队在Angewandte Chemie International Edition期刊发表题为“Confining Phosphoric Acid in Quaternized COF Channels for Ultra-stable and Fast Anhydrous Proton Transport”的研究论文,团队成员逢霄为论文第一作者,姜忠义教授为论文通讯作者.展开更多
Ionic covalent organic framework(COF)lamellar membranes are the alternative materials as promising Li^(+)conductors for all-solid-state lithium batteries.However,COF lamellar membrane suffers from poor structural stab...Ionic covalent organic framework(COF)lamellar membranes are the alternative materials as promising Li^(+)conductors for all-solid-state lithium batteries.However,COF lamellar membrane suffers from poor structural stability and inevitable cross-layer transfer resistance due to the weak interaction at interface of adjacent nanosheets.Herein,a lamellar polymer-threaded ionic COF(PEI@TpPa-SO_(3)Li)composite electrolyte with single Li^(+)conduction was prepared by assembling lithium sulfonated COF(TpPa-SO_(3)Li)nanosheets and then threading them with polyethyleneimine(PEI)chains.It reveals that the threaded PEI chains induce the oriented permutation of pore channel of PEI@TpPa-SO_(3)Li electrolyte through electrostatic interaction between-NH_(2)/-NH-and-SO_(3)Li groups.This enables the construction of continuous and aligned-SO_(3)^(-)...Li^(+)...-NH_(2)/-NH-pairs along pore channels,which act as efficient Li^(+)conducting sites and afford high Li^(+)hopping conduction(1.4×10^(-4)S cm^(-1)at 30℃)with a high Young's modulus of 408.7 MP and wide electrochemical stability window of 0~4.7 V.The assembled LiFePO_(4)‖Li and LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)‖Li half-cells achieve high discharge capacities of 155.0 mAh g^(-1)and 167.2 mAh g^(-1)at 30℃under0.2 C,respectively,with high capacity retention of 98%after 300 cycles.This study provides an alternative route to highly ion-conductive lamellar porous electrolytes for high-performance energy devices.展开更多
The two-electron oxygen reduction reaction(ORR)for H_(2)O_(2) photosynthesis is often hindered by sluggish charge kinetics and a limited number of activation sites.Theoretical predictions based on dipole moment analys...The two-electron oxygen reduction reaction(ORR)for H_(2)O_(2) photosynthesis is often hindered by sluggish charge kinetics and a limited number of activation sites.Theoretical predictions based on dipole moment analysis indicate that introducing pyrazine units enhances charge migration,leading to increased accumulation of photoinduced electrons on these units,thereby facilitating the two-site,two-electron ORR.Inspired by these theoretical insights,this work designed and fabricated a triazine-pyrazine-based covalent organic framework materials(TTDN-COFs)for H_(2)O_(2) photosynthesis via a polarity-functionalization strategy.The TTDN-COFs demonstrate a significant improvement in the photocatalytic H_(2)O_(2) production rate,reaching 2757.6μmol h^(-1) g^(-1) in pure water–3.2 times higher than that of the triazine-based COFs(TTPH-COFs).Experimental results and theoretical calculations confirm that the incorporation of pyrazine units not only enhances polarization,promoting the separation and migration of charge carriers,but also facilitates the formation of endoperoxide at both the triazine and pyrazine units.The dual adsorption activation sites lower the activation energy barrier for O_(2),thereby accelerating the overall reaction kinetics.These findings highlight the potential of functional-group-mediated polarization engineering as a promising strategy for developing COFs-based H_(2)O_(2) photosynthesis with dual activation sites.展开更多
Covalent organic skeletons(COFs)have been widely used in gas separation due to their excellent pore structure,high crystallinity,and high specific surface area.In this work,Dha Tab-COF was synthesized by solvothermal ...Covalent organic skeletons(COFs)have been widely used in gas separation due to their excellent pore structure,high crystallinity,and high specific surface area.In this work,Dha Tab-COF was synthesized by solvothermal method and filled in polyether block polyamide(PEBAX)to form mixed matrix membranes(MMMs).Various characterization methods such as Fourier transform infrared spectroscopy(FT-IR),Xray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM)and X-ray diffractometry(XRD)were used to characterize the structure of Dha Tab-COF as well as the MMMs.The effects of operating pressure,operating temperature and the content of Dha Tab-COF particles on the CO_(2)/CH_(4)separation performance of the membranes were investigated.The best separation performance with a CO_(2)permeability of 295.8 barrer(1 barrer=7.52×10^(-18)m^(3)·(STP)·m^(-2)·m·s^(-1)·Pa^(-1))and a CO_(2)/CH_(4)selectivity of 21.6 was achieved when the Dha Tab-COF content is 2%(mass),which were 45.7%and 108.1%higher than that of the pure PEBAX membrane,respectively.展开更多
基金supported by National Natural Science Foundation of China(No.51703015)Fundamental Research Funds for the Central Universities(No.2020CDJQY-A008).
文摘High piezoelectric composite films composed of poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)and ferromagnetic cobalt ferrite(CoFe_(2)O_(4))(0.00 wt%to 0.2 wt%)are prepared by a solution casting method accompanied by uniaxial stretching and high electric field poling.The decisive effect of the poling electric field on the power generating capability was confirmed by the experiments.For pure PVDF-HFP films,when the maximum electric field Emax is 120 MV/m,the calibrated open circuit voltage reaches 2.93 V,which is much higher than those poled at lower electric fields(70 MV/m:1.41 V;90 MV/m:2.11 V).Furthermore,the addition of CoFe_(2)O_(4)also influences the piezoelectricity dramatically.In the samples containing 0.15 wt%CoFe_(2)O_(4),the calibrated open circuit voltage increases to the maximum value of 3.57 V.Meanwhile,the relative fraction of theβ-phase and the crystallinity degree are 99%and 48%,respectively.The effects of CoFe_(2)O_(4)nanoparticles on initial crystallization,uniaxial stretching and high electric field poling are investigated by XRD,FTIR and DSC.
文摘2025年1月9日,天津大学姜忠义教授团队在Angewandte Chemie International Edition期刊发表题为“Confining Phosphoric Acid in Quaternized COF Channels for Ultra-stable and Fast Anhydrous Proton Transport”的研究论文,团队成员逢霄为论文第一作者,姜忠义教授为论文通讯作者.
基金supported by the financial support from the National Key Research and Development Program(2022YFB3805204,2022YFB3805201)National Natural Science Foundation of China(22478362)+2 种基金Joint Foundation for Science and Technology Research&Development Plan of Henan Province(222301420003 and 232301420038)Key Scientific and Technological Project of Henan Province(242102321032)Foundation of Henan Educational Committee(22A530003)。
文摘Ionic covalent organic framework(COF)lamellar membranes are the alternative materials as promising Li^(+)conductors for all-solid-state lithium batteries.However,COF lamellar membrane suffers from poor structural stability and inevitable cross-layer transfer resistance due to the weak interaction at interface of adjacent nanosheets.Herein,a lamellar polymer-threaded ionic COF(PEI@TpPa-SO_(3)Li)composite electrolyte with single Li^(+)conduction was prepared by assembling lithium sulfonated COF(TpPa-SO_(3)Li)nanosheets and then threading them with polyethyleneimine(PEI)chains.It reveals that the threaded PEI chains induce the oriented permutation of pore channel of PEI@TpPa-SO_(3)Li electrolyte through electrostatic interaction between-NH_(2)/-NH-and-SO_(3)Li groups.This enables the construction of continuous and aligned-SO_(3)^(-)...Li^(+)...-NH_(2)/-NH-pairs along pore channels,which act as efficient Li^(+)conducting sites and afford high Li^(+)hopping conduction(1.4×10^(-4)S cm^(-1)at 30℃)with a high Young's modulus of 408.7 MP and wide electrochemical stability window of 0~4.7 V.The assembled LiFePO_(4)‖Li and LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)‖Li half-cells achieve high discharge capacities of 155.0 mAh g^(-1)and 167.2 mAh g^(-1)at 30℃under0.2 C,respectively,with high capacity retention of 98%after 300 cycles.This study provides an alternative route to highly ion-conductive lamellar porous electrolytes for high-performance energy devices.
文摘The two-electron oxygen reduction reaction(ORR)for H_(2)O_(2) photosynthesis is often hindered by sluggish charge kinetics and a limited number of activation sites.Theoretical predictions based on dipole moment analysis indicate that introducing pyrazine units enhances charge migration,leading to increased accumulation of photoinduced electrons on these units,thereby facilitating the two-site,two-electron ORR.Inspired by these theoretical insights,this work designed and fabricated a triazine-pyrazine-based covalent organic framework materials(TTDN-COFs)for H_(2)O_(2) photosynthesis via a polarity-functionalization strategy.The TTDN-COFs demonstrate a significant improvement in the photocatalytic H_(2)O_(2) production rate,reaching 2757.6μmol h^(-1) g^(-1) in pure water–3.2 times higher than that of the triazine-based COFs(TTPH-COFs).Experimental results and theoretical calculations confirm that the incorporation of pyrazine units not only enhances polarization,promoting the separation and migration of charge carriers,but also facilitates the formation of endoperoxide at both the triazine and pyrazine units.The dual adsorption activation sites lower the activation energy barrier for O_(2),thereby accelerating the overall reaction kinetics.These findings highlight the potential of functional-group-mediated polarization engineering as a promising strategy for developing COFs-based H_(2)O_(2) photosynthesis with dual activation sites.
基金supported by the National Natural Science Foundation of China(No.22271022,No 22378327).
文摘Covalent organic skeletons(COFs)have been widely used in gas separation due to their excellent pore structure,high crystallinity,and high specific surface area.In this work,Dha Tab-COF was synthesized by solvothermal method and filled in polyether block polyamide(PEBAX)to form mixed matrix membranes(MMMs).Various characterization methods such as Fourier transform infrared spectroscopy(FT-IR),Xray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM)and X-ray diffractometry(XRD)were used to characterize the structure of Dha Tab-COF as well as the MMMs.The effects of operating pressure,operating temperature and the content of Dha Tab-COF particles on the CO_(2)/CH_(4)separation performance of the membranes were investigated.The best separation performance with a CO_(2)permeability of 295.8 barrer(1 barrer=7.52×10^(-18)m^(3)·(STP)·m^(-2)·m·s^(-1)·Pa^(-1))and a CO_(2)/CH_(4)selectivity of 21.6 was achieved when the Dha Tab-COF content is 2%(mass),which were 45.7%and 108.1%higher than that of the pure PEBAX membrane,respectively.
