Benchmark calculations on the molar atomization enthalpy, geometry, and vibrational frequencies of uranium hexafluoride (UF6) have been performed by using relativistic density functional theory (DFT) with various leve...Benchmark calculations on the molar atomization enthalpy, geometry, and vibrational frequencies of uranium hexafluoride (UF6) have been performed by using relativistic density functional theory (DFT) with various levels of relativistic effects, different types of basis sets, and exchange-correlation functionals. Scalar relativistic effects are shown to be critical for the structural properties. The spin-orbit coupling effects are important for the calculated energies, but are much less important for other calculated ground-state properties of closed-shell UF6. We conclude through systematic investigations that ZORA-and RECP-based relativistic DFT methods are both appropriate for incorporating relativistic effects. Comparisons of different types of basis sets (Slater, Gaussian, and plane-wave types) and various levels of theoretical approximation of the exchange-correlation functionals were also made.展开更多
我们基于热性质和电池的热产生行为在电池在精力损失上在房间抵抗和极化的效果上做一节新 Li 离子电池评估研究。有不同能力和电极材料的 18650 个房间的系列被测量随着费用分泌物时间和电流变化的输入和产量精力评估。基于这些测试的...我们基于热性质和电池的热产生行为在电池在精力损失上在房间抵抗和极化的效果上做一节新 Li 离子电池评估研究。有不同能力和电极材料的 18650 个房间的系列被测量随着费用分泌物时间和电流变化的输入和产量精力评估。基于这些测试的结果，我们在房间的费用分泌物过程造精力损失的一个模型，它包括朱尔热和极化热影响因素。朱尔热被房间电阻引起，这被报导，包括的 DC 抵抗和反应电阻，和反应电阻它不能容易通过平淡的测试方法被获得。用这个新方法，我们能得到全部的电阻 R 和极化参数。在 R 之间的关系，，并且温度也被调查以便为不同 Li 离子电池的系列造一个一般模型，并且研究能在表演评估，费用预言的状态并且测量电池的一致性被使用。展开更多
The precise synthesis of helicenes with topologically defined length and specific heteroatomic perturbation in the screw-like conjugated skeletons plays an emerging role in the manipulation of chiral materials.Facile,...The precise synthesis of helicenes with topologically defined length and specific heteroatomic perturbation in the screw-like conjugated skeletons plays an emerging role in the manipulation of chiral materials.Facile,selective,and programmable routes to helicenes or heterohelicenes are highly desirable yet challenging for structure-chiroptical property relationship studies.Herein,we report the synthesis and characterization of NBN-doped helicenes with boron atoms in the inner rims,enabled by the highly regioselective one-pot borylation of rationally designed precursors with,namely,fold-in or pan-out manner.The incorporation of nonbonded boron and nitrogen atoms resulted in narrow-band emission and improved optical properties for the single-stranded carbon helix.In addition,numbers and arrangement modes of fused six-membered rings have distinct effects on configurational stability and chiroptical properties,revealing that BN-[6]H with strong circular dichroism is a promising candidate for chiral sensors.The combination of experimental and theoretical studies on these helical structures might provide insights into the design of helically chiral small-molecule-based sensors or emitters.展开更多
Flexible strain sensors with high sensitivity,wide detection range,and low detection limit have continuously attracted great interest due to their tremendous application potential in areas such as health/medical-care,...Flexible strain sensors with high sensitivity,wide detection range,and low detection limit have continuously attracted great interest due to their tremendous application potential in areas such as health/medical-care,human-machine interface,as well as safety and security.While both of a high sensitivity and a wide working range are desired key parameters for a strain sensor,they are usually contrary to each other to be achieved on the same sensor due to the tightly structure dependence of both of them.Here,a flexible strain sensor with both high sensitivity and wide strain detection range is prepared based on the design of an integrated membrane containing both of parallel aligned and randomly aligned carbon nanofibers(CNFs).The parallel aligned CNF membrane(p-CNF)exhibits a low strain detection limit and high sensitivity,while the random aligned CNF membrane(r-CNF)exhibits a large strain detection range.Taking the advantages of both p-CNF and r-CNF,the strain sensor with stacked p-CNF and r-CNF(p/r-CNF)exhibits both high sensitivity and wide working range.Its gauge factor(GF)is 1,272 for strains under 0.5%and 2,266 for strain from 70%to 100%.At the same time,it can work in a wide strain range of 0.005%to 100%,fulfilling the requirements for accurately detecting full-range human motions.We demonstrated its applications in the recognition of facial expressions and joint movements.Furtherly,we constructed an intelligent lip-language recognition system,which can accurately track phonetic symbols and may help people with language disabilities,proving the potential of this strain sensor in health management and medical assistance.Besides,we foresee that the dual-alignment structure design of the p/r-CNF strain sensor may also be applied in the design of other high performance sensors.展开更多
Electronic skin and flexible wearable devices have attracted tremendous attention in the fields of human-machine interaction,energy storage,and intelligent robots.As a prevailing flexible pressure sensor with high per...Electronic skin and flexible wearable devices have attracted tremendous attention in the fields of human-machine interaction,energy storage,and intelligent robots.As a prevailing flexible pressure sensor with high performance,the piezoresistive sensor is believed to be one of the fundamental components of intelligent tactile skin.Furthermore,graphene can be used as a building block for highly flexible and wearable piezoresistive sensors owing to its light weight,high electrical conductivity,and excellent mechanical.This review provides a comprehensive summary of recent advances in graphene-based piezoresistive sensors,which we systematically classify as various configurations including one-dimensional fiber,two-dimensional thin film,and threedimensional foam geometries,followed by examples of practical applications for health monitoring,human motion sensing,multifunctional sensing,and system integration.We also present the sensing mechanisms and evaluation parameters of piezoresistive sensors.This review delivers broad insights on existing graphene-based piezoresistive sensors and challenges for the future generation of high-performance,multifunctional sensors in various applications.展开更多
Two-dimensional(2D)transition metal dichalcogenides(TMDCs)showed great potentials in 2D nanoelectronic devices due to their abundant and unique properties.The performance stability of the 2D TMDCs devices turns into o...Two-dimensional(2D)transition metal dichalcogenides(TMDCs)showed great potentials in 2D nanoelectronic devices due to their abundant and unique properties.The performance stability of the 2D TMDCs devices turns into one of the keys for their practical applications but has been rarely explored.Here,we investigated stability of MoS_(2)devices in ambient condition and contributed the device performance degradation to the surface oxidation of the contact metals with low work function,which increased the contact barrier and hindered the electron injection.We developed a new approach to recover the performance of the aged devices through the selective doping of contacts with organolithium,which prolonged the lifetime of MoS_(2)devices.Our work not only provides important insights into the stability of 2D TMDCs devices,but also opens up a new avenue for optimizing the performance of 2D MoS_(2)devices.展开更多
Scanning electrochemical microscopy(SECM)is an attractive technology to in-situ characterize the structural evolution and catalytic performance for various electrocatalysts.However,spatial and temporal resolution coup...Scanning electrochemical microscopy(SECM)is an attractive technology to in-situ characterize the structural evolution and catalytic performance for various electrocatalysts.However,spatial and temporal resolution coupling are still the obstacles that limit its wide applications.Herein,a new operation mode,Fast Scan mode,was developed by improving the dual-pass scan mode,designing novel hardware structure,and employing thermal drift calibration software to achieve a high spatial and temporal resolution simultaneously.The temporal speed can achieve 4 Hz for a high spatial resolution(less than 30 nm)image.This operation mode was employed to dynamically track the phase transition process of molybdenum disulfide(MoS_(2))over time and characterize the hydrogen evolution reaction(HER)catalytic activity on the edge of semiconducting MoS_(2)quantitatively while minimizing the diffusional broadening effect and total amount of catalytic products generated above the surface.This new approach should be useful for in-situ tracking dynamic electrochemical processes,establishing the structure-activity relationship for structural complex electrocatalysts,and offering a strategy for high-speed scanning with other electrochemical imaging techniques.展开更多
The direct conversion of cheap syngas into value-added ethanol at an industrial scale is in high demand.Herein we disclose a one-pot homogeneous homologation of methanol to ethanol with syngas via a rhodium/ruthenium ...The direct conversion of cheap syngas into value-added ethanol at an industrial scale is in high demand.Herein we disclose a one-pot homogeneous homologation of methanol to ethanol with syngas via a rhodium/ruthenium bimetallic catalytic approach.By introducing a catalytic amount of methyl iodide,methanol can be converted to ethanol with high selectivity(>91%ethanol).A syngas ratio of H_(2)/CO=4:1 was found to be optimal.Among various phosphine ligands tested,Rh-dppp catalyst gave the highest aldehyde pathway selectivity,thus providing an effective route for the synthesis of ethanol upon coupling with a Ru hydrogenation catalyst.The bite angle of the bisphosphine ligands dramatically influences the selectivity of the dual Rh/Ru metallic cascade catalysts.In line with the experimental findings,theoretical calculations predicted a rational trend of the selectivity of different bisphosphine ligands via varying bite angle properties.展开更多
Unlike biological materials that can sense mechanical force and actively remodel locally,synthetic polymers typically break down under stress.Molecular-level responses to damage with both stress-reporting and self-str...Unlike biological materials that can sense mechanical force and actively remodel locally,synthetic polymers typically break down under stress.Molecular-level responses to damage with both stress-reporting and self-strengthening functions are significant yet difficult to realize for synthetic polymers.To overcome this challenge,chemo-mechanical coupling into polymers that can simultaneously ameliorate mechanical,optical,or other functional properties of a polymer combined with mechanical treatment will offer a new principle for materials design.Here,we report a kind of elastomer in which destructive forces are channelled into productive and bond-forming reactions by using diselenide(Se–Se)as a mechanophore.Polyurethane has been functionalized with labile Se–Se bonds,whosemechanical activation generates seleno radicals that trigger radical transfer and cross-linking reactions in situ.These reactions are activated efficiently in a mechanical way by compression in bulk materials.The resulting covalent networks possess turn-on mechano-fluorescence and increased moduli,which provide the functions of stress reporting,mechano-healing,and mechano-remodeling for the deformed film.This study not only illuminates themechano-responsive nature of Se–Se bonds in the bulk state but also paves the way for the development of new stress-responsive materials.展开更多
Two-dimensional(2D)molybdenum disulfide(MoS_(2))holds great potential for various applications such as electronic devices,catalysis,lubrication,anti-corrosion and so on.Thermal evaporation is a versatile thin film dep...Two-dimensional(2D)molybdenum disulfide(MoS_(2))holds great potential for various applications such as electronic devices,catalysis,lubrication,anti-corrosion and so on.Thermal evaporation is a versatile thin film deposition technique,however,the conventional thermal evaporation techniques face challenges in producing uniform thin films of MoS_(2) due to its high melting temperature of 1375℃.As a result,only thick and rough MoS_(2) films can be obtained using these methods.To address this issue,we have designed a vacuum thermal evaporation system specifically for large-scale preparation of MoS_(2) thin films.By using K2MoS4 as the precursor,we achieved reliable deposition of uniform polycrystalline MoS_(2) thin films with a size of 50 mm×50 mm and controllable thickness ranging from 0.8 to 2.4 nm.This approach also allows for patterned deposition of MoS_(2) using shadow masks and sequential deposition of MoS_(2) and tungsten disulfide(WS_(2)),similar to conventional thermal evaporation techniques.Moreover,we have demonstrated the potential applications of the obtained MoS_(2) thin films in field effect transistors(FETs),memristors and electrocatalysts for hydrogen evolution reaction(HER).展开更多
Deep-red/near-infrared fluorescence is highly suitable for bioimaging owing to its ability to deeply penetrate tissues,organs,and live animals.However,developing organic fluorophores with high deep-red/near-infrared f...Deep-red/near-infrared fluorescence is highly suitable for bioimaging owing to its ability to deeply penetrate tissues,organs,and live animals.However,developing organic fluorophores with high deep-red/near-infrared fluorescence quantum yield(Φ_(FL))and fluorescent brightness remain a significant challenge owing to the energy gap law.Herein,we developed a straightforward and effective chalcogen-annulation strategy by introducing O,S and Se into the bay region of TDI and QDI fluorophores,realizing the increase ofΦFLand fluorescent brightness up to 10 times.To our best knowledge,this study potentially stands as the pioneering instance showcasing the anti-heavy-atom effect of chalcogens,and the absoluteΦFL(93%)and fluorescent brightness(128,200 cm^(-1)mol^(-1)L)of Se-TDI is among top deep-red/near-infrared organic fluorophores currently available.The femtosecond transient absorption(fs-TA)measurements show the absence of obvious changes of the excited state lifetime after the introduction of chalcogens in TDI and QDI fluorophores,indicating that intersystem crossing(ISC)can be neglected in TDI and QDI fluorophores.Theoretical calculations further reveal the chalcogen-annulation strategy increase the radiative rates and reduce the reorganization energy of several accepting modes at the ground state in TDI fluorophores,leading to the suppression of internal conversion(IC)processes.Our chalcogen-annulation strategy,which effectively increases the Φ_(FL)and restricts the IC processes,while remaining unaffected by the heavy-atom effect,offers novel insights and theoretical support for the design and synthesis of deep-red/near-infrared organic fluorophores with high Φ_(FL)and fluorescent brightness.展开更多
The two distinct characters of diarylethene dialdehyde derivative-photochromism and solvatochrom- ism are displayed in particular circumstances. The fluorescence of phosphorus (III) tetrabenzotri- azacorrole can be re...The two distinct characters of diarylethene dialdehyde derivative-photochromism and solvatochrom- ism are displayed in particular circumstances. The fluorescence of phosphorus (III) tetrabenzotri- azacorrole can be reversibly regulated by the three kinds of status of the diarylethene dialdehyde, col- orless ring-opened form, red ring-closed form, and blue ring-closed form, which is gated by visible light, ultraviolet light and ethanol individually or jointly. Based on this effect, a novel molecular INH logic switch is proposed.展开更多
The Seebeck effect measures the electric potential built up in materials under a temperature gradient.For organic thermoelectric materials,the Seebeck coefficient shows more complicated temperature dependence than con...The Seebeck effect measures the electric potential built up in materials under a temperature gradient.For organic thermoelectric materials,the Seebeck coefficient shows more complicated temperature dependence than conventional systems,with both monotonic increases and nonmonotonic behavior,that is,first increasing and then decreasing.The mechanism behind the phenomenon is intriguing.Through first-principles calculations coupled with the Boltzmann transport equation,we demonstrate typical trends of the Seebeck coefficient with respect to temperature through band structure analysis.展开更多
Understanding of the bonding nature of uranyl and various ligands is the key for designing robust sequestering agents for uranium extraction from seawater.In this paper thermodynamic properties related to the complexa...Understanding of the bonding nature of uranyl and various ligands is the key for designing robust sequestering agents for uranium extraction from seawater.In this paper thermodynamic properties related to the complexation reaction of uranyl(VI)in aqueous solution(i.e.existing in the form of UO2(H2O)52+)by several typical ligands(L)including acetate(CH3CO2),bicarbonate(HOCO2),carbonate(CO32),CH3(NH2)CNO(acetamidoximate,AO)and glutarimidedioximate(denoted as GDO2)have been investigated by using relativistic density functional theory(DFT).The geometries,vibrational frequencies,natural net charges,and bond orders of the formed uranyl-L complexes in aqueous solution are studied.Based on the DFT analysis we show that the binding interaction between uranyl and amidoximate ligand is the strongest among the selected complexes.The thermodynamics of the complexation reaction are examined,and the calculated results show that complexation of uranyl with amidoximate ligands is most preferred thermodynamically.Besides,reaction paths of the substitution complexation of solvated uranyl by acetate and AO have been studied,respectively.We have obtained two minima along the reaction path of solvated uranyl with acetate,the monodentate-acetate complex and the bidentate-acetate one,while only one minimum involving monodentate-AO complex has been located for AO ligand.Comparing the energy barriers of the two reaction paths,we find that complexation of uranyl with AO is more difficult in kinetics,though it is more preferable in thermodynamics.These results show that theoretical studies can help to select efficient ligands with fine-tuned thermodynamic and kinetic properties for binding uranyl in seawater.展开更多
We introduce here a work package for a National Natural Science Foundation of China Major Project. We propose to develop computational methodology starting from the theory of electronic excitation processes to predict...We introduce here a work package for a National Natural Science Foundation of China Major Project. We propose to develop computational methodology starting from the theory of electronic excitation processes to predicting the opto-electronic property for organic materials, in close collaborations with experiments. Through developing methods for the electron dynamics, considering superexchange electronic couplings, spin-orbit coupling elements between excited states, electron-phonon relaxation, intermolecular Coulomb and exchange terms we combine the statistical physics approaches including dynamic Monte Carlo, Boltzmann transport equation and Boltzmann statistics to predict the macroscopic properties of opto-electronic materials such as light-emitting efficiency, charge mobility, and exciton diffusion length. Experimental synthesis and characterization of D-A type ambipolar transport material as well as novel carbon based material will provide a test ground for the verification of theory.展开更多
Iron-substituted cobalt-free lithium-rich manganese-based materials,with advantages of high specific capacity,high safety,and low cost,have been considered as the potential cathodes for lithium ion batteries.However,c...Iron-substituted cobalt-free lithium-rich manganese-based materials,with advantages of high specific capacity,high safety,and low cost,have been considered as the potential cathodes for lithium ion batteries.However,challenges,such as poor cycle stability and fast voltage fade during cycling under high potential,hinder these materials from commercialization.Here,we developed a method to directly coat LiF on the particle surface of Li_(1.2)Ni_(0.15)Fe_(0.1)Mn_(0.55O2).A uniform and flat film was successfully formed with a thickness about 3 nm,which can effect-ively protect the cathode material from irreversible phase transition during the deintercalation of Li^(+).After surface coating with 0.5wt%LiF,the cycling stability of Li_(1.2)Ni_(0.15)Fe_(0.1)Mn_(0.55O2) cycled at high potential was significantly improved and the voltage fade was largely suppressed.展开更多
We present here a brief summary of a National Natural Science Foundation Major Project entitled "Theoretical study of the low-lying electronic excited state for molecular aggregates". The project focuses on ...We present here a brief summary of a National Natural Science Foundation Major Project entitled "Theoretical study of the low-lying electronic excited state for molecular aggregates". The project focuses on theoretical investigation of the electronic structures and dynamic processes upon photo-and electric-excitation for molecules and aggregates. We aim to develop reliable methodology to predict the optoelectronic properties of molecular materials related to the electronic excitations and to apply in the experiments. We identify two essential scientific challenges: (i) nature of intramolecular and intermolecular electronic excited states; (ii) theoretical description of the dynamic processes of the coupled motion of electronic excitations and nucleus. We propose the following four subjects of research: (i) linear scaling time-dependent density-functional theory and its application to open shell system; (ii) computational method development of electronic excited state for molecular aggregates; (iii) theoretical investigation of the time evolution of the excited state dynamics; (iv) methods to predict the optoelectronic properties starting from electronic excited state investigation for organic materials and experimental verifications.展开更多
Transition metal dichalcogenides(TMDs)possess a large number of two-dime nsional(2D)materials with novel physical and chemical properties and hold great potential applications in electronic devices,optical devices as ...Transition metal dichalcogenides(TMDs)possess a large number of two-dime nsional(2D)materials with novel physical and chemical properties and hold great potential applications in electronic devices,optical devices as well as catalysts.TMDs usually have poly-phases,such as 2H,3R and 1T.Chemical and physical properties,including electrical conductivity,superconductivity,magnetism and catalytic activity,are different for different phases of TMDs.Therefore,great efforts have been made to obtain a specific pure phase of 2D TMD materials.Here,we review the recent phase engineering research for 2D TMDs,including ion insertion,alying,temperature,defects,strain and electric field.展开更多
Nano/micro-structured germanium oxide (GeO2) was prepared using GeCl4 and KOH by a simple solution method in alkalic alcoholic solution. Different morphologies of GeO2 were obtained by changing the reaction conditions...Nano/micro-structured germanium oxide (GeO2) was prepared using GeCl4 and KOH by a simple solution method in alkalic alcoholic solution. Different morphologies of GeO2 were obtained by changing the reaction conditions. The effects of the reaction time, the concentration of the reactants, the reaction temperature and the dispersant upon the morphology of the deposited GeO2 have been investigated. The products were detected by X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM) and transmission electron microscope (TEM). Novel cross-like structures were obtained by using n-butylamine as the dispersant. The formation of the cross-like structures has been discussed and a solution-liquid-solid (SLS) mechanism was proposed.展开更多
基金NKBRSF (2006CB932305, 2007CB815200) and NNSFC (20525104).The calculations were partially performed using an HP Itanium2 cluster at Tsinghua National Laboratory for Information Science and Technology
文摘Benchmark calculations on the molar atomization enthalpy, geometry, and vibrational frequencies of uranium hexafluoride (UF6) have been performed by using relativistic density functional theory (DFT) with various levels of relativistic effects, different types of basis sets, and exchange-correlation functionals. Scalar relativistic effects are shown to be critical for the structural properties. The spin-orbit coupling effects are important for the calculated energies, but are much less important for other calculated ground-state properties of closed-shell UF6. We conclude through systematic investigations that ZORA-and RECP-based relativistic DFT methods are both appropriate for incorporating relativistic effects. Comparisons of different types of basis sets (Slater, Gaussian, and plane-wave types) and various levels of theoretical approximation of the exchange-correlation functionals were also made.
文摘我们基于热性质和电池的热产生行为在电池在精力损失上在房间抵抗和极化的效果上做一节新 Li 离子电池评估研究。有不同能力和电极材料的 18650 个房间的系列被测量随着费用分泌物时间和电流变化的输入和产量精力评估。基于这些测试的结果，我们在房间的费用分泌物过程造精力损失的一个模型，它包括朱尔热和极化热影响因素。朱尔热被房间电阻引起，这被报导，包括的 DC 抵抗和反应电阻，和反应电阻它不能容易通过平淡的测试方法被获得。用这个新方法，我们能得到全部的电阻 R 和极化参数。在 R 之间的关系，，并且温度也被调查以便为不同 Li 离子电池的系列造一个一般模型，并且研究能在表演评估，费用预言的状态并且测量电池的一致性被使用。
基金supported by the Hong Kong Research Grants Council(27301720,17304021)National Natural Science Foundation of China(22122114,22122503,21790361).
文摘The precise synthesis of helicenes with topologically defined length and specific heteroatomic perturbation in the screw-like conjugated skeletons plays an emerging role in the manipulation of chiral materials.Facile,selective,and programmable routes to helicenes or heterohelicenes are highly desirable yet challenging for structure-chiroptical property relationship studies.Herein,we report the synthesis and characterization of NBN-doped helicenes with boron atoms in the inner rims,enabled by the highly regioselective one-pot borylation of rationally designed precursors with,namely,fold-in or pan-out manner.The incorporation of nonbonded boron and nitrogen atoms resulted in narrow-band emission and improved optical properties for the single-stranded carbon helix.In addition,numbers and arrangement modes of fused six-membered rings have distinct effects on configurational stability and chiroptical properties,revealing that BN-[6]H with strong circular dichroism is a promising candidate for chiral sensors.The combination of experimental and theoretical studies on these helical structures might provide insights into the design of helically chiral small-molecule-based sensors or emitters.
基金supported by the National Natural Science Foundation of China(Nos.52125201 and 21975141)the National Key Research and Development Program of China(No.2020YFA0210702).
文摘Flexible strain sensors with high sensitivity,wide detection range,and low detection limit have continuously attracted great interest due to their tremendous application potential in areas such as health/medical-care,human-machine interface,as well as safety and security.While both of a high sensitivity and a wide working range are desired key parameters for a strain sensor,they are usually contrary to each other to be achieved on the same sensor due to the tightly structure dependence of both of them.Here,a flexible strain sensor with both high sensitivity and wide strain detection range is prepared based on the design of an integrated membrane containing both of parallel aligned and randomly aligned carbon nanofibers(CNFs).The parallel aligned CNF membrane(p-CNF)exhibits a low strain detection limit and high sensitivity,while the random aligned CNF membrane(r-CNF)exhibits a large strain detection range.Taking the advantages of both p-CNF and r-CNF,the strain sensor with stacked p-CNF and r-CNF(p/r-CNF)exhibits both high sensitivity and wide working range.Its gauge factor(GF)is 1,272 for strains under 0.5%and 2,266 for strain from 70%to 100%.At the same time,it can work in a wide strain range of 0.005%to 100%,fulfilling the requirements for accurately detecting full-range human motions.We demonstrated its applications in the recognition of facial expressions and joint movements.Furtherly,we constructed an intelligent lip-language recognition system,which can accurately track phonetic symbols and may help people with language disabilities,proving the potential of this strain sensor in health management and medical assistance.Besides,we foresee that the dual-alignment structure design of the p/r-CNF strain sensor may also be applied in the design of other high performance sensors.
基金This work was supported by the NSFC(22075019,22035005)the Young Talent Program of Henan Agricultural University(30500601).
文摘Electronic skin and flexible wearable devices have attracted tremendous attention in the fields of human-machine interaction,energy storage,and intelligent robots.As a prevailing flexible pressure sensor with high performance,the piezoresistive sensor is believed to be one of the fundamental components of intelligent tactile skin.Furthermore,graphene can be used as a building block for highly flexible and wearable piezoresistive sensors owing to its light weight,high electrical conductivity,and excellent mechanical.This review provides a comprehensive summary of recent advances in graphene-based piezoresistive sensors,which we systematically classify as various configurations including one-dimensional fiber,two-dimensional thin film,and threedimensional foam geometries,followed by examples of practical applications for health monitoring,human motion sensing,multifunctional sensing,and system integration.We also present the sensing mechanisms and evaluation parameters of piezoresistive sensors.This review delivers broad insights on existing graphene-based piezoresistive sensors and challenges for the future generation of high-performance,multifunctional sensors in various applications.
基金L.J.acknowledges the National Natural Science Foundation of China(No.21925504)Tsinghua Toyota Joint Research Fund.Z.H.C.acknowledges the National Natural Science Foundation of China(Nos.61674045,61911540074)Fundamental Research Funds for the Central Universities and the Research Funds of Renmin University of China(Nos.21XNLG27,22XNH097).
文摘Two-dimensional(2D)transition metal dichalcogenides(TMDCs)showed great potentials in 2D nanoelectronic devices due to their abundant and unique properties.The performance stability of the 2D TMDCs devices turns into one of the keys for their practical applications but has been rarely explored.Here,we investigated stability of MoS_(2)devices in ambient condition and contributed the device performance degradation to the surface oxidation of the contact metals with low work function,which increased the contact barrier and hindered the electron injection.We developed a new approach to recover the performance of the aged devices through the selective doping of contacts with organolithium,which prolonged the lifetime of MoS_(2)devices.Our work not only provides important insights into the stability of 2D TMDCs devices,but also opens up a new avenue for optimizing the performance of 2D MoS_(2)devices.
基金The support of this work by the National Natural Science Foundation of China(No.22204088)the Natural Science Foundation of Shandong Province(Nos.ZR202103040753 and ZR2020MB063)the Taishan Scholar Program of Shandong Province(No.ts201511027)is gratefully acknowledged.
文摘Scanning electrochemical microscopy(SECM)is an attractive technology to in-situ characterize the structural evolution and catalytic performance for various electrocatalysts.However,spatial and temporal resolution coupling are still the obstacles that limit its wide applications.Herein,a new operation mode,Fast Scan mode,was developed by improving the dual-pass scan mode,designing novel hardware structure,and employing thermal drift calibration software to achieve a high spatial and temporal resolution simultaneously.The temporal speed can achieve 4 Hz for a high spatial resolution(less than 30 nm)image.This operation mode was employed to dynamically track the phase transition process of molybdenum disulfide(MoS_(2))over time and characterize the hydrogen evolution reaction(HER)catalytic activity on the edge of semiconducting MoS_(2)quantitatively while minimizing the diffusional broadening effect and total amount of catalytic products generated above the surface.This new approach should be useful for in-situ tracking dynamic electrochemical processes,establishing the structure-activity relationship for structural complex electrocatalysts,and offering a strategy for high-speed scanning with other electrochemical imaging techniques.
基金This experimental investigation was financially supported by the National Natural Science Foundation of China(grant no.21991113)the Guangdong Provincial Key Laboratory of Catalysis(grant no.2020B121201002)+1 种基金the Science,Technology,and Innovation Commission of Shenzhen(grant no.20200925161222002)Theoretical calculations were supported by the National Natural Science Foundation of China(grant nos.22033005 and 22103035).
文摘The direct conversion of cheap syngas into value-added ethanol at an industrial scale is in high demand.Herein we disclose a one-pot homogeneous homologation of methanol to ethanol with syngas via a rhodium/ruthenium bimetallic catalytic approach.By introducing a catalytic amount of methyl iodide,methanol can be converted to ethanol with high selectivity(>91%ethanol).A syngas ratio of H_(2)/CO=4:1 was found to be optimal.Among various phosphine ligands tested,Rh-dppp catalyst gave the highest aldehyde pathway selectivity,thus providing an effective route for the synthesis of ethanol upon coupling with a Ru hydrogenation catalyst.The bite angle of the bisphosphine ligands dramatically influences the selectivity of the dual Rh/Ru metallic cascade catalysts.In line with the experimental findings,theoretical calculations predicted a rational trend of the selectivity of different bisphosphine ligands via varying bite angle properties.
基金support of this research by the National Natural Science Foundation of China(grant nos.21734006 and 21975178)the National Key Research and Development Program of China(grant nos.2017YFA0207800 and 2017YFA0204503)is gratefully acknowledged.
文摘Unlike biological materials that can sense mechanical force and actively remodel locally,synthetic polymers typically break down under stress.Molecular-level responses to damage with both stress-reporting and self-strengthening functions are significant yet difficult to realize for synthetic polymers.To overcome this challenge,chemo-mechanical coupling into polymers that can simultaneously ameliorate mechanical,optical,or other functional properties of a polymer combined with mechanical treatment will offer a new principle for materials design.Here,we report a kind of elastomer in which destructive forces are channelled into productive and bond-forming reactions by using diselenide(Se–Se)as a mechanophore.Polyurethane has been functionalized with labile Se–Se bonds,whosemechanical activation generates seleno radicals that trigger radical transfer and cross-linking reactions in situ.These reactions are activated efficiently in a mechanical way by compression in bulk materials.The resulting covalent networks possess turn-on mechano-fluorescence and increased moduli,which provide the functions of stress reporting,mechano-healing,and mechano-remodeling for the deformed film.This study not only illuminates themechano-responsive nature of Se–Se bonds in the bulk state but also paves the way for the development of new stress-responsive materials.
基金supported by the National Natural Science Foundation of China(No.22105114)China Postdoctoral Science Foundation(No.2020TQ0163)Tsinghua-Toyota Joint Research Fund and Tsinghua-Jiangyin Innovation Special Fund(No.2022JYTH01).
文摘Two-dimensional(2D)molybdenum disulfide(MoS_(2))holds great potential for various applications such as electronic devices,catalysis,lubrication,anti-corrosion and so on.Thermal evaporation is a versatile thin film deposition technique,however,the conventional thermal evaporation techniques face challenges in producing uniform thin films of MoS_(2) due to its high melting temperature of 1375℃.As a result,only thick and rough MoS_(2) films can be obtained using these methods.To address this issue,we have designed a vacuum thermal evaporation system specifically for large-scale preparation of MoS_(2) thin films.By using K2MoS4 as the precursor,we achieved reliable deposition of uniform polycrystalline MoS_(2) thin films with a size of 50 mm×50 mm and controllable thickness ranging from 0.8 to 2.4 nm.This approach also allows for patterned deposition of MoS_(2) using shadow masks and sequential deposition of MoS_(2) and tungsten disulfide(WS_(2)),similar to conventional thermal evaporation techniques.Moreover,we have demonstrated the potential applications of the obtained MoS_(2) thin films in field effect transistors(FETs),memristors and electrocatalysts for hydrogen evolution reaction(HER).
基金financially supported by the National Natural Science Foundation of China(NSFC)(22235005)the National Postdoctoral Program for Innovative Talents(BX20200128)+3 种基金the 69th batch of Chinese postdoctoral general support(2021M691004)Shanghai Municipal Science and Technology Major Project(2018SHZDZX03)the Fundamental Research Funds for the Central Universitiesthe Programme of Introducing Talents of Discipline to Universities(B16017)。
文摘Deep-red/near-infrared fluorescence is highly suitable for bioimaging owing to its ability to deeply penetrate tissues,organs,and live animals.However,developing organic fluorophores with high deep-red/near-infrared fluorescence quantum yield(Φ_(FL))and fluorescent brightness remain a significant challenge owing to the energy gap law.Herein,we developed a straightforward and effective chalcogen-annulation strategy by introducing O,S and Se into the bay region of TDI and QDI fluorophores,realizing the increase ofΦFLand fluorescent brightness up to 10 times.To our best knowledge,this study potentially stands as the pioneering instance showcasing the anti-heavy-atom effect of chalcogens,and the absoluteΦFL(93%)and fluorescent brightness(128,200 cm^(-1)mol^(-1)L)of Se-TDI is among top deep-red/near-infrared organic fluorophores currently available.The femtosecond transient absorption(fs-TA)measurements show the absence of obvious changes of the excited state lifetime after the introduction of chalcogens in TDI and QDI fluorophores,indicating that intersystem crossing(ISC)can be neglected in TDI and QDI fluorophores.Theoretical calculations further reveal the chalcogen-annulation strategy increase the radiative rates and reduce the reorganization energy of several accepting modes at the ground state in TDI fluorophores,leading to the suppression of internal conversion(IC)processes.Our chalcogen-annulation strategy,which effectively increases the Φ_(FL)and restricts the IC processes,while remaining unaffected by the heavy-atom effect,offers novel insights and theoretical support for the design and synthesis of deep-red/near-infrared organic fluorophores with high Φ_(FL)and fluorescent brightness.
基金the National Natural Science Foundation of China (Grant Nos.20572059, 20502013 and 20773077)National Baisc Research Program of China (Grant No.2007CB808000)
文摘The two distinct characters of diarylethene dialdehyde derivative-photochromism and solvatochrom- ism are displayed in particular circumstances. The fluorescence of phosphorus (III) tetrabenzotri- azacorrole can be reversibly regulated by the three kinds of status of the diarylethene dialdehyde, col- orless ring-opened form, red ring-closed form, and blue ring-closed form, which is gated by visible light, ultraviolet light and ethanol individually or jointly. Based on this effect, a novel molecular INH logic switch is proposed.
基金supported by the National Natural Science Foundation of China through the project“Science Center for Luminescence from Molecular Aggregates”(SCELMAgrant no.201788102)the Ministry of Science and Technology of China through the National Key R&D Plan(grant no.2017YFA0204501).
文摘The Seebeck effect measures the electric potential built up in materials under a temperature gradient.For organic thermoelectric materials,the Seebeck coefficient shows more complicated temperature dependence than conventional systems,with both monotonic increases and nonmonotonic behavior,that is,first increasing and then decreasing.The mechanism behind the phenomenon is intriguing.Through first-principles calculations coupled with the Boltzmann transport equation,we demonstrate typical trends of the Seebeck coefficient with respect to temperature through band structure analysis.
基金Acknowledgements This work was supported by the National Basic Research Program of China （No. 2011CB932400）, the National Natural Science Foundation of China （No. 21543005）, the China Postdoctoral Science Foundation （No. 2014M562391）, and the Fundamental Research Funds for the Central Universities （No. xjj2014064）. The calculations were performed by using supercomputers at the Computer Network Information Center, Chinese Academy of Sciences, Tsinghua National Laboratory for Information Science and Technology, and the Shanghai Supercomputing Center.
文摘分子的 O <sub>2</sub> 的激活是在催化黄金的氧化反应的最关键的步；然而，这个过程的内在的机制在争论下面留下。在这研究，我们用密度与包含氢的底层的帮助建议一条其他的 O <sub>2</sub> 激活小径功能的理论。这被表明共同吸附的包含 H 底层(RH ) 不仅提高 O <sub>2</sub>, 的吸附而且把一个氢原子转移到由它的转变导致 O <sub>2</sub> 激活到 hydroperoxyl (OOH ) 的邻近的 O <sub>2</sub>, 激进的种类。从 16 的H转移的激活障碍选择了 RH 混合物( H <sub>2</sub > O ， CH <sub>3</sub >哦， NH <sub>2</sub > CHCOOH ， CH <sub>3</sub > CH=CH <sub>2</sub>,( CH <sub>3</sub>)<sub>2</sub > SiH <sub>2</sub>,等等)到共同吸附的 O ，<sub>2</sub>是比在大多数情况中的 0.50 eV 低的，在温和条件下面经由 OOH 显示 O <sub>2</sub>的激活的可行性。形成的 OOH 氧化剂，与 ~ 的增加的 OO 契约长度 1.45 ? ，也通过在端点的氧原子在氧化反应直接参与，或分裂进原子氧和氢氧根(哦) 由穿过 0.24 eV 的一个相当低的精力障碍。把公司氧化用作一根探针，我们发现了 OOH 比激活的 O <sub>2</sub> 和原子氧举办优异活动。这研究为 O <sub>2</sub>, 的激活揭示一条新小径并且可以提供卓见进 nanosized 黄金的氧化催化作用。
基金the financial support by the National Natural Science Foundation of China (NSFC) (20933003 and 91026003) to JLthe Strategic Priority Research Program of the Chinese Academy of Sciences (XDA02040104)+1 种基金NSFC (21201106)the China Postdoctoral Science Foundation (2012M520297) to JS
文摘Understanding of the bonding nature of uranyl and various ligands is the key for designing robust sequestering agents for uranium extraction from seawater.In this paper thermodynamic properties related to the complexation reaction of uranyl(VI)in aqueous solution(i.e.existing in the form of UO2(H2O)52+)by several typical ligands(L)including acetate(CH3CO2),bicarbonate(HOCO2),carbonate(CO32),CH3(NH2)CNO(acetamidoximate,AO)and glutarimidedioximate(denoted as GDO2)have been investigated by using relativistic density functional theory(DFT).The geometries,vibrational frequencies,natural net charges,and bond orders of the formed uranyl-L complexes in aqueous solution are studied.Based on the DFT analysis we show that the binding interaction between uranyl and amidoximate ligand is the strongest among the selected complexes.The thermodynamics of the complexation reaction are examined,and the calculated results show that complexation of uranyl with amidoximate ligands is most preferred thermodynamically.Besides,reaction paths of the substitution complexation of solvated uranyl by acetate and AO have been studied,respectively.We have obtained two minima along the reaction path of solvated uranyl with acetate,the monodentate-acetate complex and the bidentate-acetate one,while only one minimum involving monodentate-AO complex has been located for AO ligand.Comparing the energy barriers of the two reaction paths,we find that complexation of uranyl with AO is more difficult in kinetics,though it is more preferable in thermodynamics.These results show that theoretical studies can help to select efficient ligands with fine-tuned thermodynamic and kinetic properties for binding uranyl in seawater.
基金the National Natural Science Foundation of China (21290191)
文摘We introduce here a work package for a National Natural Science Foundation of China Major Project. We propose to develop computational methodology starting from the theory of electronic excitation processes to predicting the opto-electronic property for organic materials, in close collaborations with experiments. Through developing methods for the electron dynamics, considering superexchange electronic couplings, spin-orbit coupling elements between excited states, electron-phonon relaxation, intermolecular Coulomb and exchange terms we combine the statistical physics approaches including dynamic Monte Carlo, Boltzmann transport equation and Boltzmann statistics to predict the macroscopic properties of opto-electronic materials such as light-emitting efficiency, charge mobility, and exciton diffusion length. Experimental synthesis and characterization of D-A type ambipolar transport material as well as novel carbon based material will provide a test ground for the verification of theory.
基金financially supported by the project of International Science&Technology Cooperation of China(No.2019YFE0100200)。
文摘Iron-substituted cobalt-free lithium-rich manganese-based materials,with advantages of high specific capacity,high safety,and low cost,have been considered as the potential cathodes for lithium ion batteries.However,challenges,such as poor cycle stability and fast voltage fade during cycling under high potential,hinder these materials from commercialization.Here,we developed a method to directly coat LiF on the particle surface of Li_(1.2)Ni_(0.15)Fe_(0.1)Mn_(0.55O2).A uniform and flat film was successfully formed with a thickness about 3 nm,which can effect-ively protect the cathode material from irreversible phase transition during the deintercalation of Li^(+).After surface coating with 0.5wt%LiF,the cycling stability of Li_(1.2)Ni_(0.15)Fe_(0.1)Mn_(0.55O2) cycled at high potential was significantly improved and the voltage fade was largely suppressed.
基金the National Natural Science Foundation of China (21290190)
文摘We present here a brief summary of a National Natural Science Foundation Major Project entitled "Theoretical study of the low-lying electronic excited state for molecular aggregates". The project focuses on theoretical investigation of the electronic structures and dynamic processes upon photo-and electric-excitation for molecules and aggregates. We aim to develop reliable methodology to predict the optoelectronic properties of molecular materials related to the electronic excitations and to apply in the experiments. We identify two essential scientific challenges: (i) nature of intramolecular and intermolecular electronic excited states; (ii) theoretical description of the dynamic processes of the coupled motion of electronic excitations and nucleus. We propose the following four subjects of research: (i) linear scaling time-dependent density-functional theory and its application to open shell system; (ii) computational method development of electronic excited state for molecular aggregates; (iii) theoretical investigation of the time evolution of the excited state dynamics; (iv) methods to predict the optoelectronic properties starting from electronic excited state investigation for organic materials and experimental verifications.
基金NSFC(21822502,21673058)the Key Research Program of Frontier Sciences of CAS(QYZDBSSW-SYS031)the Strategic Priority Research Program of CAS(XDB30000000).
文摘Transition metal dichalcogenides(TMDs)possess a large number of two-dime nsional(2D)materials with novel physical and chemical properties and hold great potential applications in electronic devices,optical devices as well as catalysts.TMDs usually have poly-phases,such as 2H,3R and 1T.Chemical and physical properties,including electrical conductivity,superconductivity,magnetism and catalytic activity,are different for different phases of TMDs.Therefore,great efforts have been made to obtain a specific pure phase of 2D TMD materials.Here,we review the recent phase engineering research for 2D TMDs,including ion insertion,alying,temperature,defects,strain and electric field.
基金Supported by the National Natural Science Foundation of China (Grant No. 50573039)Major State Basic Research Development Program of China (Grant No. 2006CB806200)
文摘Nano/micro-structured germanium oxide (GeO2) was prepared using GeCl4 and KOH by a simple solution method in alkalic alcoholic solution. Different morphologies of GeO2 were obtained by changing the reaction conditions. The effects of the reaction time, the concentration of the reactants, the reaction temperature and the dispersant upon the morphology of the deposited GeO2 have been investigated. The products were detected by X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM) and transmission electron microscope (TEM). Novel cross-like structures were obtained by using n-butylamine as the dispersant. The formation of the cross-like structures has been discussed and a solution-liquid-solid (SLS) mechanism was proposed.
