The facile synthesis of single-crystal hydrogen-bonded organic frameworks(HOFs)on a gram scale remains a significant challenge but is crucial for practical applications.Herein,we report a novel strategy to prepare two...The facile synthesis of single-crystal hydrogen-bonded organic frameworks(HOFs)on a gram scale remains a significant challenge but is crucial for practical applications.Herein,we report a novel strategy to prepare two three-dimensional(3D)single-crystal HOFs at ambient temperature and pressure with gram-scale products.The imine-linked oligomers were synthesized using ionic liquids as catalysts,which self-assembled in situ to form large single crystals.The optimal material,H1,exhibited iodine uptake capacities of 6.02 and 4.44 g g^(-1)from vapor and aqueous solutions,respectively,ranking among the highest reported HOFs.For the first time,the iodine-adsorbed H1 was used as an iodine source for synthesizingβ-iodoethers,achieving excellent yields comparable to those obtained using iodine as the reactant.This study not only presents a simple method for the scalable synthesis of single-crystal HOFs but also explores a potential application of iodine-adsorbed materials in organic synthesis.展开更多
Metal-halide perovskites are novel optoelectronic materials that are considered good candidates for solar harvesting and light emitting applications. In this study, we develop a reproducible and low-cost approach for ...Metal-halide perovskites are novel optoelectronic materials that are considered good candidates for solar harvesting and light emitting applications. In this study, we develop a reproducible and low-cost approach for synthesizing high- quality cesium lead halide perovskite （CsPbX3, X = CI, Br, and I or C1/Br and I/Br） nanocrystals （NCs） by direct heating of precursors in octadecene in air. Experimental results show that the particle size and composition of as-prepared CsPbX3 nanocrystals can be successfully tuned by a simple variation of reaction temperature. The emission peak positions of the as-prepared nanocrystals can be conveniently tuned from the UV to the NIR （360-700 nm） region, and the quantum yield of the as-obtained samples （green and red emissions） can reach up to 87%. The structures and chemical compositions of the as-obtained NCs were characterized by transmission electron microscopy, X-ray diffraction, and elemental analysis. This proposed synthetic route can yield large amounts of high-quality NCs with a one-batch reaction, usually on the gram scale, and could pave the way for further applications of perovskite-based light-emitting and photovoltaic solar cells.展开更多
Mn-doped all-inorganic perovskite quantum dots (QDs) provide prominent applications in the fields of low-cost light source or display,because of their remarkable properties including dual-color emission and reduced le...Mn-doped all-inorganic perovskite quantum dots (QDs) provide prominent applications in the fields of low-cost light source or display,because of their remarkable properties including dual-color emission and reduced lead content,as well as high photoluminescence quantum yields (PLQYs) and high stability.However,the existing synthesis approaches usually require hash conditions,such as high temperature and nitrogen protection,which is a major hurdler for the practical manufacturing.In addition,the significantly high Mn substitution ratio in CsPbX3 QDs is still challenging.The real dual-color emission with two strong emission peaks in the Mn-doped all-inorganic perovskite QDs has attracted great interest.Here we present a gram-scale approach to synthesize both CsPbxMn1-xCI3 and CsPb1-xMnxClyBr3-y QDs at 100 ℃ in the air with high Mn substitution ratio,up to 55.64% atomically.The as-prepared CsPb1-xMnxClyBr3-y QDs exhibit high PLQYs of 62.41% and dual-color emission with two strong emission peaks around at 400-450 nm and 600 nm,respectively.The enhanced peak at 400-450 nm is a result of the hybrid halides in CsPbBrxCl3-x host.Furthermore,the unique advantage of the optical emission and high PLQYs properties of the CsPbxMn1-xCl3 QDs has been demonstrated as invisible ink for encryption applications and polymer composites.Our gram-scale synthesis approach for Mn-doped all-inorganic perovskite QDs may boost the future research and practical applications of QDs-based white LED,spintronics,and molecular barcoding.展开更多
Electrochemical water splitting(EWS)is a highly clean and efficient method for high-purity hydrogen production.Unfortunately,EWS suffers from the sluggish and complex oxygen evolution reaction(OER)kinetics at anode.At...Electrochemical water splitting(EWS)is a highly clean and efficient method for high-purity hydrogen production.Unfortunately,EWS suffers from the sluggish and complex oxygen evolution reaction(OER)kinetics at anode.At present,the efficient,stable,and low-cost non-precious metal based OER electrocatalyst is still a great and long-term challenge for the future industrial application of EWS technology.Herein,we develop a simple and fast approach for gram-scale synthesis of flower-like cobalt-based layered double hydroxides nanosheet aggregates by ultrasonic synthesis,which show outstanding electrocatalytic performance for the oxygen evolution reaction in alkaline media,such as preeminent stability,small overpotential of 300 mV at 10 mA·cm^−2 and small Tafel slope of 110 mV·dec^−1.展开更多
Owing to their inexpensive and environmentally friendly properties,iron-based catalysts have been actively investigated for new organic reactions.In this account,we summarized our recent results on iron-catalyzed cros...Owing to their inexpensive and environmentally friendly properties,iron-based catalysts have been actively investigated for new organic reactions.In this account,we summarized our recent results on iron-catalyzed cross-coupling reactions and homo-coupling reactions.With iron-based catalysts,we constructed diverse carbon-carbon bonds,i.e.,C(sp^2)-C(sp^3),C(sp^3)-C(sp^3),C(sp^3)-C(sp^2)and C(sp^2)-C(sp^2)bonds.In order to demonstrate the usefulness of our iron protocol,we also carried out these reactions on gram-scale reactions,leading to good yields.展开更多
Rh/ZhaoPhos-catalyzed asymmetric hydroge nation of a series of(E)-2-(chro man-4-ylidene)acetates was successfully developed to prepare various chiral 4-substituted chromanes with high yields and excellent enantioselec...Rh/ZhaoPhos-catalyzed asymmetric hydroge nation of a series of(E)-2-(chro man-4-ylidene)acetates was successfully developed to prepare various chiral 4-substituted chromanes with high yields and excellent enantioselectivities(up to 99%yield,98%ee).Moreover,the gram-scale hydrogenation could be performed well in the presence of 0.02 mol%catalyst loading(TON=5000),the hydrogenation product was easily converted to access other important compounds,which demonstrated the synthetic utility of this asymmetric catalytic methodology.展开更多
目的:设计一套基于Android平台的精神疲劳检测系统,实时检测、监测被测对象的精神疲劳状态。方法:遵循准确性、易用性、便携性原则,利用脑电信号多尺度熵结合长短期记忆(long-short term memory,LSTM)人工神经网络模型,通过MindWave系...目的:设计一套基于Android平台的精神疲劳检测系统,实时检测、监测被测对象的精神疲劳状态。方法:遵循准确性、易用性、便携性原则,利用脑电信号多尺度熵结合长短期记忆(long-short term memory,LSTM)人工神经网络模型,通过MindWave系列单通道脑电信号采集设备,设计并实现包括移动端和服务器端两大部分的精神疲劳检测系统。其中移动端采用Android Studio作为开发工具,通过Java编程语言进行设计;服务器端采用Eclipse作为开发工具,在Tomcat运行环境下进行设计。结果:该系统不仅可以显示脑电信号波形图,专注度、冥想度曲线图,以及从原始脑电信号数据提取出来的α波、β波和θ波波形图,对精神疲劳等级进行量化,还可以存储用户数据,不断完善LSTM人工神经网络模型,从而使量化结果越来越准确。结论:基于Android平台的精神疲劳检测系统小型、便捷,能够简便、快速、实时地对用户精神疲劳状态进行检测与监测,可防止疲劳作业引发的安全事故。展开更多
基金supported by the National Natural Science Foundation of China(21975153)。
文摘The facile synthesis of single-crystal hydrogen-bonded organic frameworks(HOFs)on a gram scale remains a significant challenge but is crucial for practical applications.Herein,we report a novel strategy to prepare two three-dimensional(3D)single-crystal HOFs at ambient temperature and pressure with gram-scale products.The imine-linked oligomers were synthesized using ionic liquids as catalysts,which self-assembled in situ to form large single crystals.The optimal material,H1,exhibited iodine uptake capacities of 6.02 and 4.44 g g^(-1)from vapor and aqueous solutions,respectively,ranking among the highest reported HOFs.For the first time,the iodine-adsorbed H1 was used as an iodine source for synthesizingβ-iodoethers,achieving excellent yields comparable to those obtained using iodine as the reactant.This study not only presents a simple method for the scalable synthesis of single-crystal HOFs but also explores a potential application of iodine-adsorbed materials in organic synthesis.
基金This work was supported by the National Natural Science Foundation of China （Nos. 21373097 and 51072067）.
文摘Metal-halide perovskites are novel optoelectronic materials that are considered good candidates for solar harvesting and light emitting applications. In this study, we develop a reproducible and low-cost approach for synthesizing high- quality cesium lead halide perovskite （CsPbX3, X = CI, Br, and I or C1/Br and I/Br） nanocrystals （NCs） by direct heating of precursors in octadecene in air. Experimental results show that the particle size and composition of as-prepared CsPbX3 nanocrystals can be successfully tuned by a simple variation of reaction temperature. The emission peak positions of the as-prepared nanocrystals can be conveniently tuned from the UV to the NIR （360-700 nm） region, and the quantum yield of the as-obtained samples （green and red emissions） can reach up to 87%. The structures and chemical compositions of the as-obtained NCs were characterized by transmission electron microscopy, X-ray diffraction, and elemental analysis. This proposed synthetic route can yield large amounts of high-quality NCs with a one-batch reaction, usually on the gram scale, and could pave the way for further applications of perovskite-based light-emitting and photovoltaic solar cells.
基金supported by the National Key Research and Development Program of China (No.2018YFB1105100)the National Natural Science Foundation of China (Nos.51572096 and 61704061).
文摘Mn-doped all-inorganic perovskite quantum dots (QDs) provide prominent applications in the fields of low-cost light source or display,because of their remarkable properties including dual-color emission and reduced lead content,as well as high photoluminescence quantum yields (PLQYs) and high stability.However,the existing synthesis approaches usually require hash conditions,such as high temperature and nitrogen protection,which is a major hurdler for the practical manufacturing.In addition,the significantly high Mn substitution ratio in CsPbX3 QDs is still challenging.The real dual-color emission with two strong emission peaks in the Mn-doped all-inorganic perovskite QDs has attracted great interest.Here we present a gram-scale approach to synthesize both CsPbxMn1-xCI3 and CsPb1-xMnxClyBr3-y QDs at 100 ℃ in the air with high Mn substitution ratio,up to 55.64% atomically.The as-prepared CsPb1-xMnxClyBr3-y QDs exhibit high PLQYs of 62.41% and dual-color emission with two strong emission peaks around at 400-450 nm and 600 nm,respectively.The enhanced peak at 400-450 nm is a result of the hybrid halides in CsPbBrxCl3-x host.Furthermore,the unique advantage of the optical emission and high PLQYs properties of the CsPbxMn1-xCl3 QDs has been demonstrated as invisible ink for encryption applications and polymer composites.Our gram-scale synthesis approach for Mn-doped all-inorganic perovskite QDs may boost the future research and practical applications of QDs-based white LED,spintronics,and molecular barcoding.
基金sponsored by the Natural Science Basic Research Plan in Shaanxi Province of China(No.2018JM5093)the Fundamental Research Funds for the Central Universities(Nos.GK201702009 and GK201901002)111 Project(No.B14041).
文摘Electrochemical water splitting(EWS)is a highly clean and efficient method for high-purity hydrogen production.Unfortunately,EWS suffers from the sluggish and complex oxygen evolution reaction(OER)kinetics at anode.At present,the efficient,stable,and low-cost non-precious metal based OER electrocatalyst is still a great and long-term challenge for the future industrial application of EWS technology.Herein,we develop a simple and fast approach for gram-scale synthesis of flower-like cobalt-based layered double hydroxides nanosheet aggregates by ultrasonic synthesis,which show outstanding electrocatalytic performance for the oxygen evolution reaction in alkaline media,such as preeminent stability,small overpotential of 300 mV at 10 mA·cm^−2 and small Tafel slope of 110 mV·dec^−1.
基金financed by National Natural Science Foundation of China (Nos. 21672181, 21272199)GRF/RGC (Nos. 403012, CUHK14309216, CUHK14303815)+1 种基金grant to the State Key Laboratory of Synthetic Chemistry from the Innovation and Technology Commission, The Chinese Academy of Sciences-Croucher Foundation Funding Scheme for Joint LaboratoriesDirect Grant (No. 4053325) from The Chinese University of Hong Kong
文摘Owing to their inexpensive and environmentally friendly properties,iron-based catalysts have been actively investigated for new organic reactions.In this account,we summarized our recent results on iron-catalyzed cross-coupling reactions and homo-coupling reactions.With iron-based catalysts,we constructed diverse carbon-carbon bonds,i.e.,C(sp^2)-C(sp^3),C(sp^3)-C(sp^3),C(sp^3)-C(sp^2)and C(sp^2)-C(sp^2)bonds.In order to demonstrate the usefulness of our iron protocol,we also carried out these reactions on gram-scale reactions,leading to good yields.
基金the National Natural Science Foundation of China(Nos.21432007,21502145,21602172)Wuhan Morning Light Plan of Youth Science and Technology(No.2017050304010307)+4 种基金the Fundamental Research Funds for and the Central Universities(No.2042018kf0202)Shenzhen Nobel Prize Scientists Laboratory Project(No.C17783101)Science and Technology Innovation Committee of Shenzhen(No.KQTD 20150717103157174)SZDRC Discipline Construction ProgramThe Program of Introducing Talents of Discipline to Universities of China(111 Project)。
文摘Rh/ZhaoPhos-catalyzed asymmetric hydroge nation of a series of(E)-2-(chro man-4-ylidene)acetates was successfully developed to prepare various chiral 4-substituted chromanes with high yields and excellent enantioselectivities(up to 99%yield,98%ee).Moreover,the gram-scale hydrogenation could be performed well in the presence of 0.02 mol%catalyst loading(TON=5000),the hydrogenation product was easily converted to access other important compounds,which demonstrated the synthetic utility of this asymmetric catalytic methodology.
文摘目的:设计一套基于Android平台的精神疲劳检测系统,实时检测、监测被测对象的精神疲劳状态。方法:遵循准确性、易用性、便携性原则,利用脑电信号多尺度熵结合长短期记忆(long-short term memory,LSTM)人工神经网络模型,通过MindWave系列单通道脑电信号采集设备,设计并实现包括移动端和服务器端两大部分的精神疲劳检测系统。其中移动端采用Android Studio作为开发工具,通过Java编程语言进行设计;服务器端采用Eclipse作为开发工具,在Tomcat运行环境下进行设计。结果:该系统不仅可以显示脑电信号波形图,专注度、冥想度曲线图,以及从原始脑电信号数据提取出来的α波、β波和θ波波形图,对精神疲劳等级进行量化,还可以存储用户数据,不断完善LSTM人工神经网络模型,从而使量化结果越来越准确。结论:基于Android平台的精神疲劳检测系统小型、便捷,能够简便、快速、实时地对用户精神疲劳状态进行检测与监测,可防止疲劳作业引发的安全事故。
