Lead halide perovskite(LHP)nanocrystals(NCs)suffer from poor stability against environmental factors(heat,moisture,oxygen,etc.),which seriously hinders their practical application.Constructing a core-shell structure c...Lead halide perovskite(LHP)nanocrystals(NCs)suffer from poor stability against environmental factors(heat,moisture,oxygen,etc.),which seriously hinders their practical application.Constructing a core-shell structure could be an effective approach to improve the stability and optical properties of the LHP NCs.Herein,a novel strategy of water-triggered phase transformation and phospholipid(DSPE)micelle encapsulation is proposed,generating highly luminescent water-dispersed CsPbBr_(3)@CsPb_(2)Br5@DSPE core-shell-shell nanocrystals.The epitaxial growth of the CsPb_(2)Br5 shell is induced by the in-situ reconstruc-tion of the CsPbBr_(3) surface by water erosion,and the lattice mismatch with the CsPbBr_(3) core is small(3.8%).The further amphipathic phospholipid encapsulation guarantees their excellent water dispersity and stability.Revealed by the femtosecond transient absorption spectroscopy,the dense CsPb_(2)Br5@DSPE shell effectively passivates the surface of the CsPbBr_(3) core,thus improving its stability and luminescence performance.The resulting CsPbBr_(3)@CsPb_(2)Br5@DSPE nanoparticles exhibit excellent performance as fluo-rescent probes for bioimaging,aqueous inks for high-resolution pattering,and light conversion layers for LEDs,demonstrating their promising potential in multiple applications.展开更多
Ce-or La-doped Cu/SSZ-13 catalysts were prepared by a hydrothermal method and Cu,Ce or La ions were incorporated through stepwise ion exchange,The catalyst activity was measured for the ammonia selective catalytic red...Ce-or La-doped Cu/SSZ-13 catalysts were prepared by a hydrothermal method and Cu,Ce or La ions were incorporated through stepwise ion exchange,The catalyst activity was measured for the ammonia selective catalytic reduction reaction.The structure and composition of catalyst were characterized by using X-ray diffraction,scanning electron microscopy,inductively coupled plasma mass spectrometry solid-state NMR,NH_(3)-TPD techniques,and the active components were examined by XPS and XANES.The results indicate that the Ce and La doping can both completely preserve the SCR activity of Cu/SSZ-13 above 300℃,but there is also a decrease of activity below 200℃.On the other hand,Ce doping is beneficial to the formation of framework aluminum,stabilizes molecular sieve framework and Cu active sites of Cu/SSZ-13,thereby improves the catalyst hydrothermal stability.But La doping will decrease the amount of framework aluminum and Cu active sites of Cu/SSZ-13 after hydrothermally aging,even destroy zeolite CHA structure.This is quite harmful to the catalyst hydrothermal stability.展开更多
Magnetic resonance imaging (MRI) is a clinical diagnostic modality, which has become popular in hospitals around the world. Approximately 30% of MRI exams include the use of contrast agents. The research progress of t...Magnetic resonance imaging (MRI) is a clinical diagnostic modality, which has become popular in hospitals around the world. Approximately 30% of MRI exams include the use of contrast agents. The research progress of the paramagnetic resonance imaging contrast agents was described briefly. Three important approaches in the soluble paramagnetic resonance imaging contrast agents design including nonionic, tissue-specific and macromolecular contrast agents were investigated. In addition, the problems in the research and development in future were discussed.展开更多
Kasha's exciton model proposes that T1 energy levels of organic compounds are insensitive to molecular aggregation and microenvironment change because of negligible small transition dipole moments of T1 states.Thi...Kasha's exciton model proposes that T1 energy levels of organic compounds are insensitive to molecular aggregation and microenvironment change because of negligible small transition dipole moments of T1 states.This model holds true in most organic systems till now.Here we report the fabrication of twisted organic phosphors with intramolecular charge transfer characters and flexible molecular structures.When doped into different organic matrices,the twisted phosphor adopts different conformation,exhibits distinct phosphorescence colors and T1 energy levels,which violates Kasha's exciton model in organic system.Given that the change of phosphorescence colors and maxima can be readily distinguished by human eyes and conventional instrument,the twisted phosphors would be exploited as a new type of molecular probe,which would exhibit potential application in optical sensing and stimuli-responsive systems.展开更多
基金support from the National Natural Science Foundation of China(Nos.U1905213 and 52303132)the Natural Science Foundation of Hubei Province(No.2024AFB142)the Scientific Research Fund Project of Wuhan Institute of Technology(No.K2023109).
文摘Lead halide perovskite(LHP)nanocrystals(NCs)suffer from poor stability against environmental factors(heat,moisture,oxygen,etc.),which seriously hinders their practical application.Constructing a core-shell structure could be an effective approach to improve the stability and optical properties of the LHP NCs.Herein,a novel strategy of water-triggered phase transformation and phospholipid(DSPE)micelle encapsulation is proposed,generating highly luminescent water-dispersed CsPbBr_(3)@CsPb_(2)Br5@DSPE core-shell-shell nanocrystals.The epitaxial growth of the CsPb_(2)Br5 shell is induced by the in-situ reconstruc-tion of the CsPbBr_(3) surface by water erosion,and the lattice mismatch with the CsPbBr_(3) core is small(3.8%).The further amphipathic phospholipid encapsulation guarantees their excellent water dispersity and stability.Revealed by the femtosecond transient absorption spectroscopy,the dense CsPb_(2)Br5@DSPE shell effectively passivates the surface of the CsPbBr_(3) core,thus improving its stability and luminescence performance.The resulting CsPbBr_(3)@CsPb_(2)Br5@DSPE nanoparticles exhibit excellent performance as fluo-rescent probes for bioimaging,aqueous inks for high-resolution pattering,and light conversion layers for LEDs,demonstrating their promising potential in multiple applications.
基金the National Natural Science Foundation of China(21676288,21773230)Dalian National Laboratory for Clean Energy(DNL)Cooperation Fund,CAS(DNL 180406)+1 种基金QIBEBT(QIBEBT ZZBS 201805)Liaoning Revitalization Talents Program(XLYC1807207)。
文摘Ce-or La-doped Cu/SSZ-13 catalysts were prepared by a hydrothermal method and Cu,Ce or La ions were incorporated through stepwise ion exchange,The catalyst activity was measured for the ammonia selective catalytic reduction reaction.The structure and composition of catalyst were characterized by using X-ray diffraction,scanning electron microscopy,inductively coupled plasma mass spectrometry solid-state NMR,NH_(3)-TPD techniques,and the active components were examined by XPS and XANES.The results indicate that the Ce and La doping can both completely preserve the SCR activity of Cu/SSZ-13 above 300℃,but there is also a decrease of activity below 200℃.On the other hand,Ce doping is beneficial to the formation of framework aluminum,stabilizes molecular sieve framework and Cu active sites of Cu/SSZ-13,thereby improves the catalyst hydrothermal stability.But La doping will decrease the amount of framework aluminum and Cu active sites of Cu/SSZ-13 after hydrothermally aging,even destroy zeolite CHA structure.This is quite harmful to the catalyst hydrothermal stability.
基金This work was supported by the National "863" High Technology Project and the National Natural Science Foundation of China (Grant No. 29874028).
文摘Magnetic resonance imaging (MRI) is a clinical diagnostic modality, which has become popular in hospitals around the world. Approximately 30% of MRI exams include the use of contrast agents. The research progress of the paramagnetic resonance imaging contrast agents was described briefly. Three important approaches in the soluble paramagnetic resonance imaging contrast agents design including nonionic, tissue-specific and macromolecular contrast agents were investigated. In addition, the problems in the research and development in future were discussed.
基金supports from National Natural Science Foundation of China(22175194)Shanghai Scientific and Technological Innovation Project(20QA1411600,20ZR1469200)+1 种基金Hundred Talents Program from Shanghai Institute of Organic Chemistry(Y121078)Pioneer Hundred Talents Program of Chinese Academy of Sciences(E320021),and Ningbo Natural Science Foundation(2023J243).
文摘Kasha's exciton model proposes that T1 energy levels of organic compounds are insensitive to molecular aggregation and microenvironment change because of negligible small transition dipole moments of T1 states.This model holds true in most organic systems till now.Here we report the fabrication of twisted organic phosphors with intramolecular charge transfer characters and flexible molecular structures.When doped into different organic matrices,the twisted phosphor adopts different conformation,exhibits distinct phosphorescence colors and T1 energy levels,which violates Kasha's exciton model in organic system.Given that the change of phosphorescence colors and maxima can be readily distinguished by human eyes and conventional instrument,the twisted phosphors would be exploited as a new type of molecular probe,which would exhibit potential application in optical sensing and stimuli-responsive systems.
