Transition metal ditellurides(TMTDs)have versatile physical properties,including non-trivial topology,Weyl semimetal states and unique spin texture.Controlled growth of high-quality and large-scale monolayer TMTDs wit...Transition metal ditellurides(TMTDs)have versatile physical properties,including non-trivial topology,Weyl semimetal states and unique spin texture.Controlled growth of high-quality and large-scale monolayer TMTDs with preferred crystal phases is crucial for their applications.Here,we demonstrate the epitaxial growth of 1T'-MoTe_(2) on Au(111)and graphitized silicon carbide(Gr/SiC)by molecular beam epitaxy(MBE).We investigate the morphology of the grown1T'-MoTe_(2) at the atomic level by scanning tunnelling microscopy(STM)and reveal the corresponding microscopic growth mechanism.It is found that the unique ordered Te structures preferentially deposited on Au(111)regulate the growth of monolayer single crystal 1T'-MoTe_(2),while the Mo clusters were preferentially deposited on the Gr/SiC substrate,which impedes the ordered growth of monolayer MoTe_(2).We confirm that the size of single crystal 1T'-MoTe_(2) grown on Au(111)is nearly two orders of magnitude larger than that on Gr/SiC.By scanning tunnelling spectroscopy(STS),we observe that the STS spectrum of the monolayer 1T'-MoTe_(2) nano-island at the edge is different from that at the interior,which exhibits enhanced conductivity.展开更多
A high performance preoxidized poly(acrylonitrile)(O-PAN)nanofiber membrane with excellent solvent resistance,thermal stability and flexibility was fabricated by the preoxidation of electrospun PAN nanofiber membrane....A high performance preoxidized poly(acrylonitrile)(O-PAN)nanofiber membrane with excellent solvent resistance,thermal stability and flexibility was fabricated by the preoxidation of electrospun PAN nanofiber membrane.The performance of resultant O-PAN nanofiber membrane was optimized by altering the PAN concentration and preoxidation temperature.The results showed that the O-PAN nanofiber membrane which made from PAN concentration of 14%(mass)and preoxidation temperature of 250.0℃ have a more optimal comprehensive performance.In the long-term separation test of SiO2 particle(1 μm)in DMAc suspension,the permeate flux of O-PAN nanofiber membrane stabilized at 227.91 L·m^(-2)·h^(-1)(25℃,0.05 MPa)while the SiO2 rejection above 99.6%,which showed excellent solvent resistance and separation performance.In order to further explore the application of the O-PAN nanofiber membrane,the OPAN nanofiber membrane was treated with fluoride and used in oil/water separation process.The O-PAN nanofiber membrane after hydrophobic treatment showed excellent hydrophobicity and good oil/water separation performance with the permeate flux about 969.59 L·m^(-2)·h^(-1)while the separation efficiency above 96.1%.The O-PAN nanofiber membrane exhibited a potential application prospect in harsh environment separation.展开更多
Urbanization and Sustainable Development Goals(SDGs)are important global issues in the current“Anthropocene”.Climate change and the COVID-19 pandemic have exacerbated global urban problems and hindered the ability t...Urbanization and Sustainable Development Goals(SDGs)are important global issues in the current“Anthropocene”.Climate change and the COVID-19 pandemic have exacerbated global urban problems and hindered the ability to meet SDGs on time,while the broad interlinkages between urbanization and the SDGs remain poorly understood.This study shows that among the interlinkages of urbanization with 17 SDGs,synergies are observed with 151 targets(89%),among which 67(40%)have stronger synergies,and trade-offs are observed with 66 targets(39%),among which 31(18%)have stronger trade-offs.Furthermore,the synergies and trade-offs between urbanization and the achievement of SDGs are specifically analyzed based on four fundamental interaction fields:(a)public health and social welfare equality;(b)energy consumption and economic growth;(c)natural resource use and ecological/environmental impacts;and(d)international cooperation for development.Finally,based on these analyses,we propose four recommendations for sustainable urbanization,including(a)shared well-being and spatial justice for urban and rural residents;(b)guiding green and low-carbon urban development;(c)building resilient cities;and(d)promoting multilateral cooperation in cities,which can contribute to the achievement of SDGs by 2030.展开更多
Cobalt‐based materials have been considered as promising candidates to electrocatalyze water oxidation.However,the structure‐performance correlation remains largely elusive,due to the com‐plex material structures a...Cobalt‐based materials have been considered as promising candidates to electrocatalyze water oxidation.However,the structure‐performance correlation remains largely elusive,due to the com‐plex material structures and diverse performance‐influencing factors in those Co‐based catalysts.In this work,we designed two cobalt phosphates with distinct Co symmetry to explore the effect of coordination symmetry on electrocatalytic water oxidation.The two analogues have similar mor‐phology,Co valence and 6‐coordinated Co octahedron,but with different coordination symmetry.In contrast to symmetric Co_(3)(PO_(4))2·8H_(2)O,asymmetric NH_(4)CoPO_(4)·H_(2)O exhibited enhanced electrocata‐lytic water oxidation activity in a neutral aqueous solution.It is proven that,by experimental and theoretical studies,the asymmetric Co coordination sites can facilitate the surface reconstruction under anodic polarization to boost the electrocatalysis.Based on this contrastive platform with distinct symmetry differences,the preferred configuration in cobalt‐oxygen octahedrons for water oxidation has been straightforwardly assigned.展开更多
We theoretically investigate physical properties of two-dimensional(2D)Fe2Ga2S5 by employing first-principles calculations.It is found that it is an antiferromagnet with zigzag magnetic configuration orienting in the ...We theoretically investigate physical properties of two-dimensional(2D)Fe2Ga2S5 by employing first-principles calculations.It is found that it is an antiferromagnet with zigzag magnetic configuration orienting in the in-plane direction,with Néel temperatures around 160 K.The band structure of the ground state shows that it is a semiconductor with the indirect band gap of about 0.9 eV,which could be effectively tuned by the lattice strain.We predict that the carrier transport is highly anisotropic,with the electron mobility up to the order of∼103 cm 2/(V⋅s)much higher than the hole.These fantastic electronic properties make 2D Fe2Ga2S5 a promising candidate for the future spintronics.展开更多
Building on the recent systematic research on 1Hbenzo[f]indole(Bd),an important advancement in constructing ultralong organic room temperature(UORTP)materials with a universal strategy via a readily obtained unit(7H-B...Building on the recent systematic research on 1Hbenzo[f]indole(Bd),an important advancement in constructing ultralong organic room temperature(UORTP)materials with a universal strategy via a readily obtained unit(7H-Benzo[c]carbazole,BCz)is proposed in this work.Pure powders of BCz and its derivatives merely exhibit blue fluorescence at ambient condition.However,when BCz and its derivatives are dispersed into polymer or powder matrixes,strong photo-activated green UORTP can be observed from their doped systems at room temperature.Moreover,the UORTP color can be tuned between green and yellow depending on the matrix.The ultralong phosphorescence originates from the generation of charge-separated states via radicals.The matrixes play a key role in both stabilizing charge-separated states and controlling UORTP color.More interestingly,when using polymethyl methacrylate as matrix,the doped films achieve stronger photo-activated ultralong phosphorescence underwater than in air at room temperature.Comparedwith Bd,BCz achieves better performance not only in ultralong phosphorescence properties but also in practical applications.This work gains a deeper insight into the mechanism of UORTP and paves a new approach to applying organic phosphorescent materials to underwater coating and imaging.展开更多
CONSPECTUS:Two-dimensional(2D)heterostructures have created many novel properties and triggered a variety of promising applications,thus setting off a boom in the modern semiconductor industry.As the first road to ste...CONSPECTUS:Two-dimensional(2D)heterostructures have created many novel properties and triggered a variety of promising applications,thus setting off a boom in the modern semiconductor industry.As the first road to step into adequately exploring the properties and real applications,the material preparation process matters a lot.Adhering to the concept of epitaxial growth,chemical vapor deposition(CVD)shows great potential for the preparation of heterostructures for commercialization.展开更多
During the summer of 2020,southern China suffered from catastrophic flooding,the massive basin flood mainly occurred in the Yangtze River's middle and lower reaches.As of July 20,2020,the cumulative precipitation...During the summer of 2020,southern China suffered from catastrophic flooding,the massive basin flood mainly occurred in the Yangtze River's middle and lower reaches.As of July 20,2020,the cumulative precipitation since the rain season started exceeded 500 mm over most of the Yangtze River Basin,reaching>1,200 mm in some areas of the lower reaches,exceeding the same period in 1998,the severest flood year in the past 60 years.Several water gauge stations at Poyang Lake and Chaohu Lake exceeded their historical record values.The water levels in the Wuhan section of the Yangtze River were among the highest ever recorded.As of July 22,2020,45.5 million people had been affected by the floods,with 142 people having died or were missing,and the direct economic losses expected to be around 116 billion RMB(~16.5 billion US dollars).However,the losses from this flood are much lower than those of previous major floods.For example,the catastrophic 1998 flooding led to 1,526 deaths and economic losses of 255 billion RMB(~36.4 billion US dollars).The reasons behind this are worthy of further study and discussion,and may be used for reference in the future and for other countries.展开更多
基金Project supported by the National Key R&D Program of China (Grant No.2022YFA1204302)the National Natural Science Foundation of China (Grant Nos.52022029,52221001,92263107,U23A20570,62090035,U19A2090,and 12174098)+1 种基金the Hunan Provincial Natural Science Foundation of China (Grant Nos.2022JJ30142 and 2019XK2001)in part supported by the State Key Laboratory of Powder Metallurgy,Central South University。
文摘Transition metal ditellurides(TMTDs)have versatile physical properties,including non-trivial topology,Weyl semimetal states and unique spin texture.Controlled growth of high-quality and large-scale monolayer TMTDs with preferred crystal phases is crucial for their applications.Here,we demonstrate the epitaxial growth of 1T'-MoTe_(2) on Au(111)and graphitized silicon carbide(Gr/SiC)by molecular beam epitaxy(MBE).We investigate the morphology of the grown1T'-MoTe_(2) at the atomic level by scanning tunnelling microscopy(STM)and reveal the corresponding microscopic growth mechanism.It is found that the unique ordered Te structures preferentially deposited on Au(111)regulate the growth of monolayer single crystal 1T'-MoTe_(2),while the Mo clusters were preferentially deposited on the Gr/SiC substrate,which impedes the ordered growth of monolayer MoTe_(2).We confirm that the size of single crystal 1T'-MoTe_(2) grown on Au(111)is nearly two orders of magnitude larger than that on Gr/SiC.By scanning tunnelling spectroscopy(STS),we observe that the STS spectrum of the monolayer 1T'-MoTe_(2) nano-island at the edge is different from that at the interior,which exhibits enhanced conductivity.
基金supported by the Science and Technology Plans of Tianjin(18PTSYJC00170)the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(YESS20160168)The Analytical&Testing Center of Tiangong University was appreciated.
文摘A high performance preoxidized poly(acrylonitrile)(O-PAN)nanofiber membrane with excellent solvent resistance,thermal stability and flexibility was fabricated by the preoxidation of electrospun PAN nanofiber membrane.The performance of resultant O-PAN nanofiber membrane was optimized by altering the PAN concentration and preoxidation temperature.The results showed that the O-PAN nanofiber membrane which made from PAN concentration of 14%(mass)and preoxidation temperature of 250.0℃ have a more optimal comprehensive performance.In the long-term separation test of SiO2 particle(1 μm)in DMAc suspension,the permeate flux of O-PAN nanofiber membrane stabilized at 227.91 L·m^(-2)·h^(-1)(25℃,0.05 MPa)while the SiO2 rejection above 99.6%,which showed excellent solvent resistance and separation performance.In order to further explore the application of the O-PAN nanofiber membrane,the OPAN nanofiber membrane was treated with fluoride and used in oil/water separation process.The O-PAN nanofiber membrane after hydrophobic treatment showed excellent hydrophobicity and good oil/water separation performance with the permeate flux about 969.59 L·m^(-2)·h^(-1)while the separation efficiency above 96.1%.The O-PAN nanofiber membrane exhibited a potential application prospect in harsh environment separation.
基金the National Natural Science Foundation of China(Grants No.42171204,42121001 and 41822104)Chinese Academy of Sciences Basic Frontier Science Research Program from 0 to 1 Original Innovation Project(Grant No.ZDBS-LY-DQC005)the Chinese Academy of Sciences Strategic Pilot Project(Class A)(Grant No.XDA23100301).
文摘Urbanization and Sustainable Development Goals(SDGs)are important global issues in the current“Anthropocene”.Climate change and the COVID-19 pandemic have exacerbated global urban problems and hindered the ability to meet SDGs on time,while the broad interlinkages between urbanization and the SDGs remain poorly understood.This study shows that among the interlinkages of urbanization with 17 SDGs,synergies are observed with 151 targets(89%),among which 67(40%)have stronger synergies,and trade-offs are observed with 66 targets(39%),among which 31(18%)have stronger trade-offs.Furthermore,the synergies and trade-offs between urbanization and the achievement of SDGs are specifically analyzed based on four fundamental interaction fields:(a)public health and social welfare equality;(b)energy consumption and economic growth;(c)natural resource use and ecological/environmental impacts;and(d)international cooperation for development.Finally,based on these analyses,we propose four recommendations for sustainable urbanization,including(a)shared well-being and spatial justice for urban and rural residents;(b)guiding green and low-carbon urban development;(c)building resilient cities;and(d)promoting multilateral cooperation in cities,which can contribute to the achievement of SDGs by 2030.
文摘Cobalt‐based materials have been considered as promising candidates to electrocatalyze water oxidation.However,the structure‐performance correlation remains largely elusive,due to the com‐plex material structures and diverse performance‐influencing factors in those Co‐based catalysts.In this work,we designed two cobalt phosphates with distinct Co symmetry to explore the effect of coordination symmetry on electrocatalytic water oxidation.The two analogues have similar mor‐phology,Co valence and 6‐coordinated Co octahedron,but with different coordination symmetry.In contrast to symmetric Co_(3)(PO_(4))2·8H_(2)O,asymmetric NH_(4)CoPO_(4)·H_(2)O exhibited enhanced electrocata‐lytic water oxidation activity in a neutral aqueous solution.It is proven that,by experimental and theoretical studies,the asymmetric Co coordination sites can facilitate the surface reconstruction under anodic polarization to boost the electrocatalysis.Based on this contrastive platform with distinct symmetry differences,the preferred configuration in cobalt‐oxygen octahedrons for water oxidation has been straightforwardly assigned.
基金Supported by the National Natural Science Foundation of China(Grant Nos.11704117,11774084,U19A2090 and 11974076)the Project of Educational Commission of Hunan Province of China(Grant No.18A003).
文摘We theoretically investigate physical properties of two-dimensional(2D)Fe2Ga2S5 by employing first-principles calculations.It is found that it is an antiferromagnet with zigzag magnetic configuration orienting in the in-plane direction,with Néel temperatures around 160 K.The band structure of the ground state shows that it is a semiconductor with the indirect band gap of about 0.9 eV,which could be effectively tuned by the lattice strain.We predict that the carrier transport is highly anisotropic,with the electron mobility up to the order of∼103 cm 2/(V⋅s)much higher than the hole.These fantastic electronic properties make 2D Fe2Ga2S5 a promising candidate for the future spintronics.
基金supported by the National Natural Science Foundation of China(62375079,52072117,62375081,52221001,51972105,62090035,U19A2090,and 61905071)the National Key R&D Program of China(2022YFA1204300)+4 种基金the Key Program of Science and Technology Department of Hunan Province(2019XK2001 and 2020XK2001)the Key Research and Development Plan of Hunan Province(2023GK2012)the Open Project Program of Key Laboratory of Nanodevices and Applications,Suzhou Institute of Nano-Tech and Nano-Bionics,Chinese Academy of Sciences(22ZS01)the Hunan Provincial Natural Science Foundation of China(2021JJ30132)the China Scholarship Council.
基金supported by the National Natural Science Foundation of China(grant nos.22175015 and 21704002)the Beijing Natural Science Foundation(grant no.2182054)+1 种基金the Big Science Project from BUCT(grant no.XK180301)the Fundamental Research Funds for the Central Universities to Z.Y.Ma.
文摘Building on the recent systematic research on 1Hbenzo[f]indole(Bd),an important advancement in constructing ultralong organic room temperature(UORTP)materials with a universal strategy via a readily obtained unit(7H-Benzo[c]carbazole,BCz)is proposed in this work.Pure powders of BCz and its derivatives merely exhibit blue fluorescence at ambient condition.However,when BCz and its derivatives are dispersed into polymer or powder matrixes,strong photo-activated green UORTP can be observed from their doped systems at room temperature.Moreover,the UORTP color can be tuned between green and yellow depending on the matrix.The ultralong phosphorescence originates from the generation of charge-separated states via radicals.The matrixes play a key role in both stabilizing charge-separated states and controlling UORTP color.More interestingly,when using polymethyl methacrylate as matrix,the doped films achieve stronger photo-activated ultralong phosphorescence underwater than in air at room temperature.Comparedwith Bd,BCz achieves better performance not only in ultralong phosphorescence properties but also in practical applications.This work gains a deeper insight into the mechanism of UORTP and paves a new approach to applying organic phosphorescent materials to underwater coating and imaging.
基金the National Natural Science Foundation of China(nos.61505051,51902098,62090035,U19A2090,and 1217409)the Key Program of Science and Technology Department of Hunan Province(nos.2019XK2001 and 2020XK2001)+1 种基金the Science and Technology Innovation Program of Hunan Province(no.2021RC3061)the Natural Science Foundation of Hunan Province(nos.2021JJ20016 and 2021JJ30132).
文摘CONSPECTUS:Two-dimensional(2D)heterostructures have created many novel properties and triggered a variety of promising applications,thus setting off a boom in the modern semiconductor industry.As the first road to step into adequately exploring the properties and real applications,the material preparation process matters a lot.Adhering to the concept of epitaxial growth,chemical vapor deposition(CVD)shows great potential for the preparation of heterostructures for commercialization.
基金Funded by the Strategic Priority Research Program of the Chinese Academy of Sciences(grant no.XDA23090303)the NSFC Major International(Regional)Joint Research Project(grant no.41520104002)the Youth Innovation Promotion Association.
文摘During the summer of 2020,southern China suffered from catastrophic flooding,the massive basin flood mainly occurred in the Yangtze River's middle and lower reaches.As of July 20,2020,the cumulative precipitation since the rain season started exceeded 500 mm over most of the Yangtze River Basin,reaching>1,200 mm in some areas of the lower reaches,exceeding the same period in 1998,the severest flood year in the past 60 years.Several water gauge stations at Poyang Lake and Chaohu Lake exceeded their historical record values.The water levels in the Wuhan section of the Yangtze River were among the highest ever recorded.As of July 22,2020,45.5 million people had been affected by the floods,with 142 people having died or were missing,and the direct economic losses expected to be around 116 billion RMB(~16.5 billion US dollars).However,the losses from this flood are much lower than those of previous major floods.For example,the catastrophic 1998 flooding led to 1,526 deaths and economic losses of 255 billion RMB(~36.4 billion US dollars).The reasons behind this are worthy of further study and discussion,and may be used for reference in the future and for other countries.
