Sodium-ion batteries have emerged as promising alternatives to lithium-ion batteries due to their abundant raw material reserves,low cost,enhanced safety,and environmental sustainability.Na_(2)Fe_(2)OS_(2),featuring a...Sodium-ion batteries have emerged as promising alternatives to lithium-ion batteries due to their abundant raw material reserves,low cost,enhanced safety,and environmental sustainability.Na_(2)Fe_(2)OS_(2),featuring a layered anti-perovskite structure,has attracted significant interest for its high capacity and facile synthesis.In this study,density functional theory calculations were performed to systematically investigate the phase stability,ionic conductivity,and voltage characteristics of Na_(2)Fe_(2)OS_(2)as a model system for anti-perovskite layered cathode materials.The compound exhibits excellent phase stability,and its equilibrium potential was calculated for the series Na_(x)Fe_(2)OCh_(2)(0<±<2)(where Ch represents chalcogenides).Naion transport analysis using the climbing image nudged elastic band method reveals a relatively low migration barrier(~0.47eV)along a dingonal pathway,indicating efficient Na^(+)mobility.To expand the materials design space,we systematically explored the effects of substituting Fe with various transition metals and replacing S with Se in NaaTM_(2)OCh_(2)structures.Among the variants studied,Na_(2)Mn_(2)OS_(2) demonstrates the most favorable combination of high voltage(~2.51V),robust phase stability,and superior energy density(~427 W-h/kg).This comprehensive comparison of transition metal substitutions provides vnluable insights for the rational design and experimental development of next-generation anti-perovskite layered cathode materials for sodium-ion batteries.展开更多
Inspired by the recent discovery of breathing kagome materials Nb_(3)Cl_(8) and Nb_(3)TeCl_(7),we have explored the influence of the breathing effect on the Hubbard model of the kagome lattice.Utilizing the determinan...Inspired by the recent discovery of breathing kagome materials Nb_(3)Cl_(8) and Nb_(3)TeCl_(7),we have explored the influence of the breathing effect on the Hubbard model of the kagome lattice.Utilizing the determinant quantum Monte Carlo method,we first investigated the average sign problem in the breathing kagome lattice,which is influenced by both the breathing strength and the interaction strength.Secondly,we calculated the electronic kinetic energy,the direct current conductivity,and the electronic density of states at the Fermi level to determine the critical interaction strength for the metal-insulator transition.Our results indicate that the breathing effect,in conjunction with the interaction strength,drives the kagome system from a metal to an insulator.Finally,we evaluated the magnetic properties and constructed a phase diagram incorporating both transport and magnetic properties.The phase diagram reveals that as the interaction strength increases,the system transitions from a paramagnetic metal to a Mott insulator.Our research provides theoretical guidance for utilizing the breathing effect to control the band gaps,conductivity,and magnetic properties of kagome materials with electronic interactions.展开更多
Facile fabrication of two-dimensional nanostructures to expose more active sites is a critical factor in developing high-efficiency transition metal sulfide material catalysts.Herein,the one-step solvent-free solid-st...Facile fabrication of two-dimensional nanostructures to expose more active sites is a critical factor in developing high-efficiency transition metal sulfide material catalysts.Herein,the one-step solvent-free solid-state method was developed to synthesize Co_(9)S_(8)(denoted as S-Co_(9)S_(8))with a nanoflake structure and much improved electronic conductivity,and the carbon substrate or template was not required.Benefiting from the unique properties.展开更多
Conventional methods for quantifying thermoelectric anisotropy rely on precisely aligned crystals,which are time-consuming and error-prone.To address this,we propose a tensor inversion method integrating transport mea...Conventional methods for quantifying thermoelectric anisotropy rely on precisely aligned crystals,which are time-consuming and error-prone.To address this,we propose a tensor inversion method integrating transport measurements with EBSD-derived Euler angles to determine the intrinsic tensors of as-grown bismuth crystals.This method reconstructs the full second-rank thermoelectric tensors—including electrical resistivity,thermal conductivity,and the Seebeck coefficient—by transforming transport data between the sample coordinate system and the crystal coordinate system.The inverted tensor components of pure bismuth show excellent agreement with reported principal-axis values,validating the accuracy of this method.Moreover,the reversibility of the tensor inversion approach allows for complete visualization of the directional dependence of the thermoelectric figure of merit(zT),revealing its full angular and crystallographic orientation distribution for the first time.This bidirectional framework not only provides a convenient pathway for the reconstruction of intrinsic transport tensors but also enables the prediction of orientation-dependent properties,thereby offering a robust tool for analyzing anisotropic transport behavior and guiding the optimization of thermoelectric performance.展开更多
The incorporation of photoactive units into metal–organic frameworks(MOFs)is of particular interest due to their ability to endow the MOFs with additional properties such as photomagnetism,photomodulated electrical c...The incorporation of photoactive units into metal–organic frameworks(MOFs)is of particular interest due to their ability to endow the MOFs with additional properties such as photomagnetism,photomodulated electrical conductivity,and photocatalytic properties.Perylenediimides(PDIs),as a class of organic dye molecules with strong visible-light absorption ability and high photochemical activity,have attracted considerable interest because of their consecutive photoinduced electron transfer processes for the generation of energetic PDI radical anions.In this context,a novel photoactive MOF based on a perylenediimide derivative,Zn_(2)(diPyPI-Cl_(4))(NDC)_(2)·3DMF(MOF 1)(diPyPI-Cl_(4)=N,N’-bis(pyridyl)-1,6,7,12-tetrachloroperylene-3,4,9,10-tetracarboxy bisimide,H_(2)NDC=2,6-naphthalenedicarboxylic acid),has been successfully constructed,which exhibits a porous three-dimensional framework with a pcu topology.MOF 1 that acts as an efficient and recyclable electron-transfer photocatalyst is applied for boosting the iodoperfluoroalkylation of alkenes and oxidation of amines to imines under mild conditions with high yields and excellent substrate application ranges.This photocatalyst has the advantages of high efficiency,low catalytic loading and easy availability,which is highly feasible from a synthetic point of view.展开更多
A promising thermoelectric figure of merit,zT,of~1.3 at 725 K was obtained in high quality crystalline ingots of Ge_(1−x)Bi_(x)Te.The substitution of Bi^(3+)in a Ge^(2+)sublattice of GeTe significantly reduces the exc...A promising thermoelectric figure of merit,zT,of~1.3 at 725 K was obtained in high quality crystalline ingots of Ge_(1−x)Bi_(x)Te.The substitution of Bi^(3+)in a Ge^(2+)sublattice of GeTe significantly reduces the excess hole concentration due to the aliovalent donor dopant nature of Bi^(3+).Reduction in carrier density optimizes electrical conductivity,and subsequently enhances the Seebeck coefficient in Ge_(1−x)Bi_(x)Te.More importantly,a low lattice thermal conductivity of~1.1 W m^(−1) K^(−1) for Ge_(0.90)Bi_(0.10)Te was achieved,which is due to the collective phonon scattering from meso-structured grain boundaries,nano-structured precipitates,nano-scale defect layers,and solid solution point defects.We have obtained a reasonably high mechanical stability for the Ge_(1−x)Bi_(x)Te samples.The measured Vickers microhardness value of the high performance sample is∼165 HV,which is comparatively higher than that of state-of-the-art thermoelectric materials,such as PbTe,Bi_(2)Te_(3),and Cu_(2)Se.展开更多
Thermoelectric(TE)materials,capable of interconverting heat and electricity,exhibit significant promise for applications in heat harvesting and solid-state cooling.The conversion efficiency of TE materials can be asse...Thermoelectric(TE)materials,capable of interconverting heat and electricity,exhibit significant promise for applications in heat harvesting and solid-state cooling.The conversion efficiency of TE materials can be assessed using the dimensionless figure of merit,defined as zT=α^(2)σT/(κ_(L)+κ_(e)),where T,α,σ,κ_(L),κ_(e)are the absolute temperature,Seebeck coefficient,electrical conductivity,lattice thermal conductivity,and electronic thermal conductivity,respectively[1].High-performance TE materials with elevated zT values are predominantly found among compounds comprising of the elements from groups IV,V,and VI.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12404264 and 22209067)Shenzhen Basic Research Program(Natural Science Foundation)Key Project of Basic Research(Grant No.JCYJ20241202123916023)Shenzhen Science and Technology Program(Grant No.KQTD20200820113047086)。
文摘Sodium-ion batteries have emerged as promising alternatives to lithium-ion batteries due to their abundant raw material reserves,low cost,enhanced safety,and environmental sustainability.Na_(2)Fe_(2)OS_(2),featuring a layered anti-perovskite structure,has attracted significant interest for its high capacity and facile synthesis.In this study,density functional theory calculations were performed to systematically investigate the phase stability,ionic conductivity,and voltage characteristics of Na_(2)Fe_(2)OS_(2)as a model system for anti-perovskite layered cathode materials.The compound exhibits excellent phase stability,and its equilibrium potential was calculated for the series Na_(x)Fe_(2)OCh_(2)(0<±<2)(where Ch represents chalcogenides).Naion transport analysis using the climbing image nudged elastic band method reveals a relatively low migration barrier(~0.47eV)along a dingonal pathway,indicating efficient Na^(+)mobility.To expand the materials design space,we systematically explored the effects of substituting Fe with various transition metals and replacing S with Se in NaaTM_(2)OCh_(2)structures.Among the variants studied,Na_(2)Mn_(2)OS_(2) demonstrates the most favorable combination of high voltage(~2.51V),robust phase stability,and superior energy density(~427 W-h/kg).This comprehensive comparison of transition metal substitutions provides vnluable insights for the rational design and experimental development of next-generation anti-perovskite layered cathode materials for sodium-ion batteries.
基金supported by the National Science Foundation of China(Grant No.12474218)Beijing Natural Science Foundation(Grant Nos.1242022 and 1252022).
文摘Inspired by the recent discovery of breathing kagome materials Nb_(3)Cl_(8) and Nb_(3)TeCl_(7),we have explored the influence of the breathing effect on the Hubbard model of the kagome lattice.Utilizing the determinant quantum Monte Carlo method,we first investigated the average sign problem in the breathing kagome lattice,which is influenced by both the breathing strength and the interaction strength.Secondly,we calculated the electronic kinetic energy,the direct current conductivity,and the electronic density of states at the Fermi level to determine the critical interaction strength for the metal-insulator transition.Our results indicate that the breathing effect,in conjunction with the interaction strength,drives the kagome system from a metal to an insulator.Finally,we evaluated the magnetic properties and constructed a phase diagram incorporating both transport and magnetic properties.The phase diagram reveals that as the interaction strength increases,the system transitions from a paramagnetic metal to a Mott insulator.Our research provides theoretical guidance for utilizing the breathing effect to control the band gaps,conductivity,and magnetic properties of kagome materials with electronic interactions.
基金supported by the National Natural Science Foundation of China(12274471,11922415)Guangdong Basic and Applied Basic Research Foundation(2022A1515011168,2019A1515011718)+1 种基金Key Research&Development Program of Guangdong Province,China(2019B110209003)supported by the Guangzhou Basic and Applied Basic Research Foundation(202102021118).
文摘Facile fabrication of two-dimensional nanostructures to expose more active sites is a critical factor in developing high-efficiency transition metal sulfide material catalysts.Herein,the one-step solvent-free solid-state method was developed to synthesize Co_(9)S_(8)(denoted as S-Co_(9)S_(8))with a nanoflake structure and much improved electronic conductivity,and the carbon substrate or template was not required.Benefiting from the unique properties.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFA0718700)the National Natural Science Foundation of China(Grant Nos.52172259 and 52472191)+1 种基金the Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(Grant No.2021ZZ127)the Natural Science Foundation of Fujian Province of China(Grant No.2025J010017)。
文摘Conventional methods for quantifying thermoelectric anisotropy rely on precisely aligned crystals,which are time-consuming and error-prone.To address this,we propose a tensor inversion method integrating transport measurements with EBSD-derived Euler angles to determine the intrinsic tensors of as-grown bismuth crystals.This method reconstructs the full second-rank thermoelectric tensors—including electrical resistivity,thermal conductivity,and the Seebeck coefficient—by transforming transport data between the sample coordinate system and the crystal coordinate system.The inverted tensor components of pure bismuth show excellent agreement with reported principal-axis values,validating the accuracy of this method.Moreover,the reversibility of the tensor inversion approach allows for complete visualization of the directional dependence of the thermoelectric figure of merit(zT),revealing its full angular and crystallographic orientation distribution for the first time.This bidirectional framework not only provides a convenient pathway for the reconstruction of intrinsic transport tensors but also enables the prediction of orientation-dependent properties,thereby offering a robust tool for analyzing anisotropic transport behavior and guiding the optimization of thermoelectric performance.
基金supported by the National Natural Science Foundation of China(No.21961030)the Application Basis Research Project of Yunnan Province Science and Technology Department(202101AU070004)the Yunnan Province Thousand Youth Talents Plan,the Program of Innovative Research Team(in science and technology)in University of Yunnan Province and the Scientific and Technological Innovation Team for Green Catalysis and Energy Material in Yunnan Institutions of Higher Learning.
文摘The incorporation of photoactive units into metal–organic frameworks(MOFs)is of particular interest due to their ability to endow the MOFs with additional properties such as photomagnetism,photomodulated electrical conductivity,and photocatalytic properties.Perylenediimides(PDIs),as a class of organic dye molecules with strong visible-light absorption ability and high photochemical activity,have attracted considerable interest because of their consecutive photoinduced electron transfer processes for the generation of energetic PDI radical anions.In this context,a novel photoactive MOF based on a perylenediimide derivative,Zn_(2)(diPyPI-Cl_(4))(NDC)_(2)·3DMF(MOF 1)(diPyPI-Cl_(4)=N,N’-bis(pyridyl)-1,6,7,12-tetrachloroperylene-3,4,9,10-tetracarboxy bisimide,H_(2)NDC=2,6-naphthalenedicarboxylic acid),has been successfully constructed,which exhibits a porous three-dimensional framework with a pcu topology.MOF 1 that acts as an efficient and recyclable electron-transfer photocatalyst is applied for boosting the iodoperfluoroalkylation of alkenes and oxidation of amines to imines under mild conditions with high yields and excellent substrate application ranges.This photocatalyst has the advantages of high efficiency,low catalytic loading and easy availability,which is highly feasible from a synthetic point of view.
基金partially supported by the DRDO-JNCASR collaborative project and DAE-BRNS project(37(3)20/01/2015/BRNS)support of the DST Ramanujan Fellowship and Sheikh Saqr Laboratory.
文摘A promising thermoelectric figure of merit,zT,of~1.3 at 725 K was obtained in high quality crystalline ingots of Ge_(1−x)Bi_(x)Te.The substitution of Bi^(3+)in a Ge^(2+)sublattice of GeTe significantly reduces the excess hole concentration due to the aliovalent donor dopant nature of Bi^(3+).Reduction in carrier density optimizes electrical conductivity,and subsequently enhances the Seebeck coefficient in Ge_(1−x)Bi_(x)Te.More importantly,a low lattice thermal conductivity of~1.1 W m^(−1) K^(−1) for Ge_(0.90)Bi_(0.10)Te was achieved,which is due to the collective phonon scattering from meso-structured grain boundaries,nano-structured precipitates,nano-scale defect layers,and solid solution point defects.We have obtained a reasonably high mechanical stability for the Ge_(1−x)Bi_(x)Te samples.The measured Vickers microhardness value of the high performance sample is∼165 HV,which is comparatively higher than that of state-of-the-art thermoelectric materials,such as PbTe,Bi_(2)Te_(3),and Cu_(2)Se.
基金supported by JST(Japan Science and Technology Agency)Mirai Program JPMJMI19A1.Xinyuan Wang gratefully acknowledges financial support from the China Scholarship Council(CSC)supported by“Advanced Research Infrastructure for Materials and Nanotechnology in Japan(ARIM)”(No.JPMXP 1223NM5150)of the Ministry of Education,Culture,Sports,Science and Technology(MEXT).
文摘Thermoelectric(TE)materials,capable of interconverting heat and electricity,exhibit significant promise for applications in heat harvesting and solid-state cooling.The conversion efficiency of TE materials can be assessed using the dimensionless figure of merit,defined as zT=α^(2)σT/(κ_(L)+κ_(e)),where T,α,σ,κ_(L),κ_(e)are the absolute temperature,Seebeck coefficient,electrical conductivity,lattice thermal conductivity,and electronic thermal conductivity,respectively[1].High-performance TE materials with elevated zT values are predominantly found among compounds comprising of the elements from groups IV,V,and VI.
