Electrospinning is a versatile and popular method for the fabrication of ultrafine fibers and many parameters in electrospinning can be adjusted when ideal micro/nanofibers are required.In particular,the selection of ...Electrospinning is a versatile and popular method for the fabrication of ultrafine fibers and many parameters in electrospinning can be adjusted when ideal micro/nanofibers are required.In particular,the selection of a proper solvent condition is a fundamental and crucial step to produce electrospun ultrafine fibers.In this study,a commonly used biomaterial,polylactic acid(PLA),was dissolved in 7 different solvents and PLA micro/nanofibers were prepared by electrospinning.The morphology,porosity,mechanical property and static contact angle were characterized to determine the quality of the obtained product.The results show that different solvent conditions have a significant effect on both the diameter,surface smooth degree of PLA micro/nanofibers and the properties of the fibrous membranes.展开更多
Flexible strain sensors play an important role in electronic skins,wearable medical devices,and advanced robots.Herein,a highly sensitive and fast response optical strain sensor with two evanescently coupled optical m...Flexible strain sensors play an important role in electronic skins,wearable medical devices,and advanced robots.Herein,a highly sensitive and fast response optical strain sensor with two evanescently coupled optical micro/nanofibers(MNFs)embedded in a polydimethylsiloxane(PDMS)film is proposed.The strain sensor exhibits a gauge factor as high as 64.5 for strain≤0.5%and a strain resolution of 0.0012%which corresponds to elongation of 120 nm on a 1 cm long device.As a proof-of-concept,highly sensitive fingertip pulse measurement is realized.The properties of fast temporal frequency response up to 30 kHz and a pressure sensitivity of 102 kPa^(−1) enable the sensor for sound detection.Such versatile sensor could be of great use in physiological signal monitoring,voice recognition and micro-displacement detection.展开更多
Electronic skin,a class of wearable electronic sensors that mimic the functionalities of human skin,has made remarkable success in applications including health monitoring,human-machine interaction and electronic-biol...Electronic skin,a class of wearable electronic sensors that mimic the functionalities of human skin,has made remarkable success in applications including health monitoring,human-machine interaction and electronic-biological interfaces.While electronic skin continues to achieve higher sensitivity and faster response,its ultimate performance is fundamentally limited by the nature of low-frequency AC currents.Herein,highly sensitive skin-like wearable optical sensors are demonstrated by embedding glass micro/nanofibers(MNFs)in thin layers of polydimethylsiloxane(PDMS).Enabled by the transition from guided modes into radiation modes of the waveguiding MNFs upon external stimuli,the skin-like optical sensors show ultrahigh sensitivity(1870 k·Pa^-1),low detection limit(7 mPa)and fast response(10μs)for pressure sensing,significantly exceeding the performance metrics of state-of-the-art electronic skins.Electromagnetic interference(EMI)-free detection of high-frequency vibrations,wrist pulse and human voice are realized.Moreover,a five-sensor optical data glove and a 2×2-MNF tactile sensor are demonstrated.These initial results pave the way toward a new category of optical devices ranging from ultrasensitive wearable sensors to optical skins.展开更多
Sn_(1−x)Er_(x)O_(2)(x=0%,8%,16%,24%)micro/nanofibers were prepared by electrospinning combined with heat treatment using erbium nitrate,stannous chloride and polyvinylpyrrolidone(PVP)as raw materials.The target produc...Sn_(1−x)Er_(x)O_(2)(x=0%,8%,16%,24%)micro/nanofibers were prepared by electrospinning combined with heat treatment using erbium nitrate,stannous chloride and polyvinylpyrrolidone(PVP)as raw materials.The target products were characterized by thermogravimetric analyzer,X-ray diffrotometer,fourier transform infrared spectrometer,scanning electron microscope,spectrophotometer and infrared emissivity tester,and the effects of Er^(3+)doping on its infrared and laser emissivity were studied.At the same time,the Sn_(1−x)Er_(x)O_(2)(x=0%,16%)doping models were constructed based on the first principles of density functional theory,and the related optoelectronic properties such as their energy band structure,density of states,reflectivity and dielectric constant were analyzed,and further explained the mechanism of Er^(3+)doping on SnO_(2)infrared emissivity and laser absorption from the point of electronic structure.The results showed that after calcination at 600℃,single rutile type SnO_(2)was formed,and the crystal structure was not changed by doping Er^(3+).The calcined products showed good fiber morphology,and the average fiber diameter was 402 nm.The infrared emissivity and resistivity of the samples both decreased first and then increased with the increase of Er^(3+)doping amount.When x=16%,the infrared emis-sivity of the sample was at least 0.71;and Er^(3+)doping can effectively reduce the reflectivity of SnO_(2)at 1.06μm and 1.55μm,when x=16%,its reflectivity at 1.06μm and 1.55μm are 50.5%and 40%,respectively,when x=24%,the reflectivity at 1.06μm and 1.55μm wavelengths are 47.3%and 42.1%,respectively.At the same time,the change of carrier concentration and electron transition before and after Er^(3+)doping were described by first-principle calculation,and the regulation mechanism of infrared emissivity and laser reflectivity was explained.This study provides a certain experimental and theoretical basis for the development of a single-type,light-weight and easily prepared infrared and laser compatible-stealth material.展开更多
With the miniaturization and high-frequency evolution of antennas in 5G/6G communications,aerospace,and transportation,polymer composite papers integrating superior wave-transparent performance and thermal conductivit...With the miniaturization and high-frequency evolution of antennas in 5G/6G communications,aerospace,and transportation,polymer composite papers integrating superior wave-transparent performance and thermal conductivity for radar antenna systems are urgently needed.Herein,a down-top strategy was employed to synthesize poly(p-phenylene benzobisoxazole)precursor nanofibers(prePNF).The prePNF was then uniformly mixed with fluorinated graphene(FG)to fabricate FG/PNF composite papers through consecutively suction filtration,hot-pressing,and thermal annealing.The hydroxyl and amino groups in prePNF enhanced the stability of FG/prePNF dispersion,while the increasedπ-πinteractions between PNF and FG after annealing improved their compatibility.The preparation time and cost of PNF paper was significantly reduced when applying this strategy,which enabled its large-scale production.Furthermore,the prepared FG/PNF composite papers exhibited excellent wave-transparent performance and thermal conductivity.When the mass fraction of FG was 40 wt%,the FG/PNF composite paper prepared via the down-top strategy achieved the wave-transparent coefficient(|T|2)of 96.3%under 10 GHz,in-plane thermal conductivity(λ_(∥))of 7.13 W m^(−1)K^(−1),and through-plane thermal conductivity(λ_(⊥))of 0.67 W m^(−1)K^(−1),outperforming FG/PNF composite paper prepared by the top-down strategy(|T|2=95.9%,λ_(∥)=5.52 W m^(−1)K^(−1),λ_(⊥)=0.52 W m^(−1)K^(−1))and pure PNF paper(|T|2=94.7%,λ_(∥)=3.04 W m^(−1)K^(−1),λ_(⊥)=0.24 W m^(−1)K^(−1)).Meanwhile,FG/PNF composite paper(with 40 wt%FG)through the down-top strategy also demonstrated outstanding mechanical properties with tensile strength and toughness reaching 197.4 MPa and 11.6 MJ m^(−3),respectively.展开更多
The lack of macro-continuity and mechanical strength of covalent organic frameworks(COFs)has significantly limited their practical applications.Here,we propose an“alcohol-triggered defect cleavage”strategy to precis...The lack of macro-continuity and mechanical strength of covalent organic frameworks(COFs)has significantly limited their practical applications.Here,we propose an“alcohol-triggered defect cleavage”strategy to precisely regulate the growth and stacking of COF grains through a moderate reversed Schiff base reaction,realizing the direct synthesis of COF nanofibers(CNFs)with high aspect ratio(L/D=103.05)and long length(>20μm).An individual CNF exhibits a biomimetic scale-like architecture,achieving superior flexibility and fatigue resistance under dynamic bending via a multiscale stress dissipation mechanism.Taking advantages of these structural features,we engineer CNF aerogels(CNF-As)with programmable porous structures(e.g.,honeycomb,lamellar,isotropic)via directional ice-template methodology.CNF-As demonstrate 100%COF content,high specific surface area(396.15 m^(2)g^(-1))and superelasticity(~0%elastic deformation after 500 compression cycles at 50%strain),outperforming most COF-based counterparts.Compared with the conventional COF aerogels,the unique structural features of CNF-A enable it to perform outstandingly in uranium extraction,with an 11.72-fold increment in adsorption capacity(920.12 mg g^(-1))and adsorption rate(89.9%),and a 2.48-fold improvement in selectivity(U/V=2.31).This study provides a direct strategy for the development of next-generation COF materials with outstanding functionality and structural robustness.展开更多
Soft actuators based on cellulose with highly electro-responsive properties have attracted significant attention in the fields of wearable devices,medical and healthcare devices,soft robots,and human-computer interact...Soft actuators based on cellulose with highly electro-responsive properties have attracted significant attention in the fields of wearable devices,medical and healthcare devices,soft robots,and human-computer interactions.However,existing cellulose-based soft actuators still need to be improved in terms of actuation displacement,bending strain,and driving frequency.Herein,we report a highly responsive ionic actuator using carboxylated cellulose nanofibers from wood pulp(CNFp),graphene nanosheets(GN),and ionic liquids(IL).The CNFp-IL-GN actuator exhibited a large specific capacitance of 749.11 mF/cm^(2)under a 25 mV/s scan rate,a large mechanical displacement(25 mm peak-to-peak)under 2.0 V at 0.1 Hz,a broad actuation frequency(0.1 to 10 Hz),and long working stability.Furthermore,bioinspired applications,including bionic dragonflies and artificial soft-touch fingers,have been demonstrated.These results demonstrate that the proposed actuator is a significant method for advancing soft actuators,artificial muscles,and bioinspired robots.展开更多
Extreme cold weather seriously harms human thermoregulatory system,necessitating high-performance insulating garments to maintain body temperature.However,as the core insulating layer,advanced fibrous materials always...Extreme cold weather seriously harms human thermoregulatory system,necessitating high-performance insulating garments to maintain body temperature.However,as the core insulating layer,advanced fibrous materials always struggle to balance mechanical properties and thermal insulation,resulting in their inability to meet the demands for both washing resistance and personal protection.Herein,inspired by the natural spring-like structures of cucumber tendrils,a superelastic and washable micro/nanofibrous sponge(MNFS)based on biomimetic helical fibers is directly prepared utilizing multiple-jet electrospinning technology for high-performance thermal insulation.By regulating the conductivity of polyvinylidene fluoride solution,multiple-jet ejection and multiple-stage whipping of jets are achieved,and further control of phase separation rates enables the rapid solidification of jets to form spring-like helical fibers,which are directly entangled to assemble MNFS.The resulting MNFS exhibits superelasticity that can withstand large tensile strain(200%),1000 cyclic tensile or compression deformations,and retain good resilience even in liquid nitrogen(-196℃).Furthermore,the MNFS shows efficient thermal insulation with low thermal conductivity(24.85 mW m^(-1)K^(-1)),close to the value of dry air,and remains structural stability even after cyclic washing.This work offers new possibilities for advanced fibrous sponges in transportation,environmental,and energy applications.展开更多
As electromagnetic(EM)pollution intensifies,EM protection materials have garnered significant attention.However,the development of lightweight and efficient EM protection materials still faces numerous challenges.In t...As electromagnetic(EM)pollution intensifies,EM protection materials have garnered significant attention.However,the development of lightweight and efficient EM protection materials still faces numerous challenges.In this work,a bilayered metal-organic framework(MOF),specifically zeolitic imidazolate framework-8@zeolitic imidazolate framework-67(ZIF-8@ZIF-67),is initially prepared.Subsequently,through a combination of electrospinning and high-temperature carbonization processes,a heterodimensional structure featuring carbon-based dodecahedrons tandemly arranged on carbon nanofibers was obtained.The carbonization at various temperatures modulated the nanofibers'conductive network and graphitization of dodecahedrons,thereby regulating the dielectric response,which is crucial for tuning the EM properties of the material.Furthermore,dielectric-magnetic synergy also plays a certain role in optimizing microwave absorption performance.The Co-CHD@CNF800 with 60 wt%loading content demonstrates a minimum reflection loss(RL)of-53.6 dB at 1.83 mm,while 40 wt%loading content exhibits a maximum effective absorption bandwidth(EAB)of 6 GHz at 2.67 mm.Additionally,Co-CHD@CNF1000 with 80 wt%exhibits remarkable electromagnetic interference(EMI)shielding performance.Importantly,an EM energy conversion device has been constructed that can effectively recover and utilize harmful EM energy.This research presents an innovative approach to the development of lightweight and efficient EM protection materials and devices.展开更多
Carbon-based electromagnetic wave(EMW)absorbing materials attached with metal sulfides famous for good dielectric properties are favored by researchers,which can form heterogeneous interfaces and thus provide suppleme...Carbon-based electromagnetic wave(EMW)absorbing materials attached with metal sulfides famous for good dielectric properties are favored by researchers,which can form heterogeneous interfaces and thus provide supplementary loss mechanisms to make up for the deficiencies of a single material in energy attenuation.Here,Co_(9)S_(8)/Co@coral-like carbon nanofibers(CNFs)/porous carbon hybrids are successfully fabricated by hydrothermal and chemical vapor deposition.The samples have exceptional EMW absorb-ing properties,with a minimum reflection loss of-57.48 dB at a thickness of 2.94 mm and an effective absorption bandwidth of up to 6.10 GHz at only 2.20 mm.The interlocking structure formed by Co@coral-like CNFs,interfacial polarization generated by heterostructure of Co_(9)S_(8),abundant defects and large specific surface area resulted from porous properties are important factors in attaining magnetic-dielectric balance and excellent absorption performance.Different matrixes are selected instead of paraffin to investigate the effect of matrix materials on EMW absorbing capacity.Besides,the EMW attenuation potential for practical applications is also demonstrated by radar cross-section simulations,electric field intensity distribution and power loss density.This work provides a novel strategy for designing outstanding EMW absorbers with unique microstructures using facile and low-cost synthetic routes.展开更多
Ultrafast fiber lasers are indispensable components in the field of ultrafast optics,and their continuous performance advancements are driving the progress of this exciting discipline.Micro/Nanofibers(MNFs)possess uni...Ultrafast fiber lasers are indispensable components in the field of ultrafast optics,and their continuous performance advancements are driving the progress of this exciting discipline.Micro/Nanofibers(MNFs)possess unique properties,such as a large fractional evanescent field,flexible and controllable dispersion,and high nonlinearity,making them highly valuable for generating ultrashort pulses.Particularly,in tasks involving mode-locking and dispersion and nonlinearity management,MNFs provide an excellent platform for investigating intriguing nonlinear dynamics and related phenomena,thereby promoting the advancement of ultrafast fiber lasers.In this paper,we present an introduction to the mode evolution and characteristics of MNFs followed by a comprehensive review of recent advances in using MNFs for ultrafast optics applications including evanescent field modulation and control,dispersion and nonlinear management techniques,and nonlinear dynamical phenomenon exploration.Finally,we discuss the potential application prospects of MNFs in the realm of ultrafast optics.展开更多
Microporous carbon nanofibers (MCNFs) derived from polyacrylonitrile nanofibers were fabricated via electrospinning technology and phase separation in the presence of polyvinylpyrrolidone (PVP). PVP together with a mi...Microporous carbon nanofibers (MCNFs) derived from polyacrylonitrile nanofibers were fabricated via electrospinning technology and phase separation in the presence of polyvinylpyrrolidone (PVP). PVP together with a mixed solvent of N, N-Dimethylformamide and dimethyl sulfoxide was used as pore forming agent. The influences of PVP content in casting solution on the structure and electrochemical performance of the MCNFs were also investigated. The highest capacitance of 200 F/g was obtained on a three-electrode system at a scan rate of 0.5 A/g. The good performance was owing to the high specific surface area and the large amount of micro-pores, which enhanced the absorption and the transportation efficiency of electrolyte ion during charge/discharge process. This research indicated that the combination of electrospinning and phase separation technology could be used to fabricate microporous carbon nanofibers as electrode materials for supercapacitors with high specific surface area and outstanding electrochemical performance. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.展开更多
Currently, the oxygen reduction reaction(ORR) mainly depends on precious metal platinum(Pt) catalysts. However, Pt-based catalysts have several shortcomings, such as high cost, scarcity, and poor long-term stability. ...Currently, the oxygen reduction reaction(ORR) mainly depends on precious metal platinum(Pt) catalysts. However, Pt-based catalysts have several shortcomings, such as high cost, scarcity, and poor long-term stability. Therefore, development of e cient metal-free electrocatalysts to replace Pt-based electrocatalysts is important. In this study, we successfully prepared nitrogen-and fluorinecodoped microporous carbon nanofibers(N, F-MCFs) via electrospinning polyacrylonitrile/polyvinylidene fluoride/polyvinylpyrrolidone(PAN/PVDF/PVP) tricomponent polymers followed by a hydrothermal process and thermal treatment, which was achieved for the first time in the literature. The results indicated that N, F-MCFs exhibit a high catalytic activity(E_(onset): 0.94 V vs. RHE, E_(1/2): 0.81 V vs. RHE, and electron transfer number: 4.0) and considerably better stability and methanol tolerance for ORR in alkaline solutions as compared to commercial Pt/carbon(Pt/C, 20 wt%) catalysts. Furthermore, in acidic media, N, F-MCFs showed a four-electron transfer pathway for ORR. This study provides a new strategy for in situ synthesis of N, F-MCFs as highly e cient metal-free electrocatalysts for ORR in fuel cells.展开更多
Application of novel radio technologies and equip-ment inevitably leads to electromagnetic pollution.One-dimensional polymer-based composite membrane structures have been shown to be an effective strategy to obtain hi...Application of novel radio technologies and equip-ment inevitably leads to electromagnetic pollution.One-dimensional polymer-based composite membrane structures have been shown to be an effective strategy to obtain high-performance microwave absorbers.Herein,we reported a one-dimensional N-doped carbon nanofibers material which encapsulated the hollow Co_(3)SnC_(0.7) nano-cubes in the fiber lumen by electrospinning.Space charge stacking formed between nanoparticles can be channeled by longitudinal fibrous structures.The dielectric constant of the fibers is highly related to the carbonization temperature,and the great impedance matching can be achieved by synergetic effect between Co_(3)SnC_(0.7) and carbon network.At 800℃,the necklace-like Co_(3)SnC_(0.7)/CNF with 5%low load achieves an excellent RL value of−51.2 dB at 2.3 mm and the effective absorption bandwidth of 7.44 GHz with matching thickness of 2.5 mm.The multiple electromagnetic wave(EMW)reflections and interfacial polarization between the fibers and the fibers internal contribute a major effect to attenuating the EMW.These strategies for regulating electromagnetic performance can be expanded to other electromagnetic functional materials which facilitate the development of emerging absorbers.展开更多
The aim of this study was to elucidate the optimized fabrication factors influencing the formation and properties of shellac(SHL) nanofibers loaded with an antimicrobial monolaurin(ML). The main and interaction effect...The aim of this study was to elucidate the optimized fabrication factors influencing the formation and properties of shellac(SHL) nanofibers loaded with an antimicrobial monolaurin(ML). The main and interaction effects of formulation and process parameters including SHL content(35%–40% w/w), ML content(1%–3% w/w), applied voltage(9–27 kV) and flow rate(0.4–1.2 ml/h) on the characteristic of nanofibers were investigated through a total of 19 experiments based on a full factorial design with three replicated center points. As a result, the SHL content was the major parameter affecting fiber diameter. Another response result revealed that the SHL content would be also the most significant negative impact on amount of beads. An increase in the concentration of SHL leaded to a reduction in the amount of beads. From the results of characterization study, it was proved that ML might be entrapped between the chains of SHL during the electrospinning process exhibiting an excellent encapsulation. According to the response surface area, small(?488 nm) and beadless(?0.48) fibers were obtained with the SHL and ML contents of 37.5% and 1.1% w/w respectively, at the applied voltage of 18 k V and the flow rate of 0.8 ml/h. In addition, the results of the kill-kinetic studies showed that SHL nanofibers loaded with ML exhibited an excellent antibacterial activity against Staphylococcus aureus, while Escherichia coli was less affected due to the hydrophilic structure of the its outer membrane. ML also exerted an antifun-gal activity by reducing the number of Candida albicans colonies. Based on their structural and antimicrobial properties, SHL nanofibers containing ML could be potentially used as a medicated dressing for wound treatment.展开更多
Platinum nanoparticles supported on graphite nanofibers (GNFs) were prepared bymicrowave assistant heating polyol process. TEM images showed that microwave prepared Ptnanoparticles supported on GNFs were small and uni...Platinum nanoparticles supported on graphite nanofibers (GNFs) were prepared bymicrowave assistant heating polyol process. TEM images showed that microwave prepared Ptnanoparticles supported on GNFs were small and uniform, and the average diameter was about 3.4nm. Cyclic voltammetric test showed that Pt/GNFs exhibited very high electrocatalytic activity formethanol oxidation.展开更多
Aramid papers (AP), made of aramid fibers, demonstrate superiority in electrical insulation applications. Unfortunately, the strength and electrical insulating properties of AP remain suboptimal, primarily due to the ...Aramid papers (AP), made of aramid fibers, demonstrate superiority in electrical insulation applications. Unfortunately, the strength and electrical insulating properties of AP remain suboptimal, primarily due to the smooth surface and chemical inertness of aramid fibers. Herein, AP are modified via the nacre-mimetic structure composed of aramid nanofibers (ANF) and carbonylated basalt nanosheets (CBSNs). This is achieved by impregnating AP into an ANF-CBSNs (A-C) suspension containing a 3D ANF framework as the matrix and 2D CBSNs as fillers. The resultant biomimetic composite papers (AP/A-C composite papers) exhibit a layered “brick-and-mortar” structure, demonstrating superior mechanical and electrical insulating properties. Notably, the tensile strength and breakdown strength of AP/A-C5 composite papers reach 39.69 MPa and 22.04 kV mm^(−1), respectively, representing a 155 % and 85 % increase compared to those of the control AP. These impressive properties are accompanied with excellent volume resistivity, exceptional dielectric properties, impressive folding endurance, outstanding heat insulation, and remarkable flame retardance. The nacre-inspired strategy offers an effective approach for producing highly promising electrical insulating papers for advanced electrical equipment.展开更多
Before densification by chemical vapor infiltration,carbon or SiC nanofibers were grown on the surface of carbon fibers by catalytic chemical vapor deposition using electroplated Ni as catalyst.The modification and me...Before densification by chemical vapor infiltration,carbon or SiC nanofibers were grown on the surface of carbon fibers by catalytic chemical vapor deposition using electroplated Ni as catalyst.The modification and mechanism of nanofibers on the pyrocarbon deposition during chemical vapor infiltration were investigated.The results show that the nanofibers improve the surface activity of the carbon fibers and become active nucleation centers during chemical vapor infiltration.They can induce the ordered deposition of pyrocarbon and adjust the interface bonding between pyrocarbon and carbon fibers during the infiltration.展开更多
Manganese-based chalcogenides have significant potential as anodes for sodium-ion batteries(SIBs) due to their high theoretical specific capacity, abundant natural reserves, and environmental friendliness. However, th...Manganese-based chalcogenides have significant potential as anodes for sodium-ion batteries(SIBs) due to their high theoretical specific capacity, abundant natural reserves, and environmental friendliness. However, their application is hindered by poor cycling stability, resulting from severe volume changes during cycling and slow reaction kinetics due to their complex crystal structure. Here, an efficient and straightforward strategy was employed to in-situ encapsulate single-phase porous nanocubic MnS_(0.5)Se_(0.5) into carbon nanofibers using electrospinning and the hard template method, thus forming a necklace-like porous MnS_(0.5)Se_(0.5)-carbon nanofiber composite(MnS_(0.5)Se_(0.5)@N-CNF). The introduction of Se significantly impacts both the composition and microstructure of MnS_(0.5)Se_(0.5), including lattice distortion that generates additional defects, optimization of chemical bonds, and a nano-spatially confined design. In situ/ex-situ characterization and density functional theory calculations verified that this MnS_(0.5)Se_(0.5)@N-CNF allevi- ates the volume expansion and facilitates the transfer of Na+/electron. As expected, MnS_(0.5)Se_(0.5)@N-CNF anode demonstrates excellent sodium storage performance, characterized by high initial Coulombic efficiency(90.8%), high-rate capability(370.5 m Ahg^(-1) at 10 Ag^(-1)) and long durability(over 5000 cycles at 5 Ag^(-1)). The MnS_(0.5)Se_(0.5)@N-CNF//NVP@C full cell, assembled with MnS_(0.5)Se_(0.5)@N-CNF as anode and Na_(3)V_(2)(PO_4)_(3)@C as cathode, exhibits a high energy density of 254 Wh kg^(-1) can be provided. This work presents a novel strategy to optimize the design of anode materials through structural engineering and Se substitution, while also elucidating the underlying reaction mechanisms.展开更多
基金the Doctoral Scientific Research Foundation of Xi’an Polytechnic University(BS15015)Thousand Talents Program of Shaanxi Province,San-qin Scholar Foundation of Shaanxi Province,Scientific Research Program Funded by Shaanxi Provincial Education Department(Program No.20JK0651)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Electrospinning is a versatile and popular method for the fabrication of ultrafine fibers and many parameters in electrospinning can be adjusted when ideal micro/nanofibers are required.In particular,the selection of a proper solvent condition is a fundamental and crucial step to produce electrospun ultrafine fibers.In this study,a commonly used biomaterial,polylactic acid(PLA),was dissolved in 7 different solvents and PLA micro/nanofibers were prepared by electrospinning.The morphology,porosity,mechanical property and static contact angle were characterized to determine the quality of the obtained product.The results show that different solvent conditions have a significant effect on both the diameter,surface smooth degree of PLA micro/nanofibers and the properties of the fibrous membranes.
基金We are grateful for financial supports from the National Natural Science Foundation of China(No.61975173)the National Key Research and Development Program of China(No.SQ2019YFC170311)+3 种基金the Major Scientific Research Project of Zhejiang Lab(No.2019MC0AD01)the Key Research and Development Project of Zhejiang Province(No.2021C05003)the Quantum Joint Funds of the Natural Foundation of Shandong Province(No.ZR2020LLZ007)the CIE-Tencent Robotics X Rhino-Bird Focused Research Program(No.2020-01-006).
文摘Flexible strain sensors play an important role in electronic skins,wearable medical devices,and advanced robots.Herein,a highly sensitive and fast response optical strain sensor with two evanescently coupled optical micro/nanofibers(MNFs)embedded in a polydimethylsiloxane(PDMS)film is proposed.The strain sensor exhibits a gauge factor as high as 64.5 for strain≤0.5%and a strain resolution of 0.0012%which corresponds to elongation of 120 nm on a 1 cm long device.As a proof-of-concept,highly sensitive fingertip pulse measurement is realized.The properties of fast temporal frequency response up to 30 kHz and a pressure sensitivity of 102 kPa^(−1) enable the sensor for sound detection.Such versatile sensor could be of great use in physiological signal monitoring,voice recognition and micro-displacement detection.
基金This work was supported by the National Key Research and Development Program of China(2016YFB1001300)the National Natural Science Foundation of China(No.11527901)the Fundamental Research Funds for the Central Universities.
文摘Electronic skin,a class of wearable electronic sensors that mimic the functionalities of human skin,has made remarkable success in applications including health monitoring,human-machine interaction and electronic-biological interfaces.While electronic skin continues to achieve higher sensitivity and faster response,its ultimate performance is fundamentally limited by the nature of low-frequency AC currents.Herein,highly sensitive skin-like wearable optical sensors are demonstrated by embedding glass micro/nanofibers(MNFs)in thin layers of polydimethylsiloxane(PDMS).Enabled by the transition from guided modes into radiation modes of the waveguiding MNFs upon external stimuli,the skin-like optical sensors show ultrahigh sensitivity(1870 k·Pa^-1),low detection limit(7 mPa)and fast response(10μs)for pressure sensing,significantly exceeding the performance metrics of state-of-the-art electronic skins.Electromagnetic interference(EMI)-free detection of high-frequency vibrations,wrist pulse and human voice are realized.Moreover,a five-sensor optical data glove and a 2×2-MNF tactile sensor are demonstrated.These initial results pave the way toward a new category of optical devices ranging from ultrasensitive wearable sensors to optical skins.
基金supported by the Key Research and Development Program of Hebei Province(No.21351501D)A Provincial and Ministerial Scientific Research Project(LJ20212C031165)Basic Frontier Science and Technology Innovation Project of Army Engineering University of PLA(KYSZJQZL2210)。
文摘Sn_(1−x)Er_(x)O_(2)(x=0%,8%,16%,24%)micro/nanofibers were prepared by electrospinning combined with heat treatment using erbium nitrate,stannous chloride and polyvinylpyrrolidone(PVP)as raw materials.The target products were characterized by thermogravimetric analyzer,X-ray diffrotometer,fourier transform infrared spectrometer,scanning electron microscope,spectrophotometer and infrared emissivity tester,and the effects of Er^(3+)doping on its infrared and laser emissivity were studied.At the same time,the Sn_(1−x)Er_(x)O_(2)(x=0%,16%)doping models were constructed based on the first principles of density functional theory,and the related optoelectronic properties such as their energy band structure,density of states,reflectivity and dielectric constant were analyzed,and further explained the mechanism of Er^(3+)doping on SnO_(2)infrared emissivity and laser absorption from the point of electronic structure.The results showed that after calcination at 600℃,single rutile type SnO_(2)was formed,and the crystal structure was not changed by doping Er^(3+).The calcined products showed good fiber morphology,and the average fiber diameter was 402 nm.The infrared emissivity and resistivity of the samples both decreased first and then increased with the increase of Er^(3+)doping amount.When x=16%,the infrared emis-sivity of the sample was at least 0.71;and Er^(3+)doping can effectively reduce the reflectivity of SnO_(2)at 1.06μm and 1.55μm,when x=16%,its reflectivity at 1.06μm and 1.55μm are 50.5%and 40%,respectively,when x=24%,the reflectivity at 1.06μm and 1.55μm wavelengths are 47.3%and 42.1%,respectively.At the same time,the change of carrier concentration and electron transition before and after Er^(3+)doping were described by first-principle calculation,and the regulation mechanism of infrared emissivity and laser reflectivity was explained.This study provides a certain experimental and theoretical basis for the development of a single-type,light-weight and easily prepared infrared and laser compatible-stealth material.
基金the support from the National Natural Science Foundation of China(52473083,52373089,52403085)Natural Science Basic Research Program of Shaanxi(2024JC-TBZC-04)+2 种基金the Innovation Capability Support Program of Shaanxi(2024RS-CXTD-57)Natural Science Basic Research Plan in Shaanxi Province of China(2024JC-YBMS-279)Natural Science Foundation of Chongqing,China(2023NSCQMSX2547)
文摘With the miniaturization and high-frequency evolution of antennas in 5G/6G communications,aerospace,and transportation,polymer composite papers integrating superior wave-transparent performance and thermal conductivity for radar antenna systems are urgently needed.Herein,a down-top strategy was employed to synthesize poly(p-phenylene benzobisoxazole)precursor nanofibers(prePNF).The prePNF was then uniformly mixed with fluorinated graphene(FG)to fabricate FG/PNF composite papers through consecutively suction filtration,hot-pressing,and thermal annealing.The hydroxyl and amino groups in prePNF enhanced the stability of FG/prePNF dispersion,while the increasedπ-πinteractions between PNF and FG after annealing improved their compatibility.The preparation time and cost of PNF paper was significantly reduced when applying this strategy,which enabled its large-scale production.Furthermore,the prepared FG/PNF composite papers exhibited excellent wave-transparent performance and thermal conductivity.When the mass fraction of FG was 40 wt%,the FG/PNF composite paper prepared via the down-top strategy achieved the wave-transparent coefficient(|T|2)of 96.3%under 10 GHz,in-plane thermal conductivity(λ_(∥))of 7.13 W m^(−1)K^(−1),and through-plane thermal conductivity(λ_(⊥))of 0.67 W m^(−1)K^(−1),outperforming FG/PNF composite paper prepared by the top-down strategy(|T|2=95.9%,λ_(∥)=5.52 W m^(−1)K^(−1),λ_(⊥)=0.52 W m^(−1)K^(−1))and pure PNF paper(|T|2=94.7%,λ_(∥)=3.04 W m^(−1)K^(−1),λ_(⊥)=0.24 W m^(−1)K^(−1)).Meanwhile,FG/PNF composite paper(with 40 wt%FG)through the down-top strategy also demonstrated outstanding mechanical properties with tensile strength and toughness reaching 197.4 MPa and 11.6 MJ m^(−3),respectively.
基金supported by the National Natural Science Foundation of China(No.52403035)the Shanghai Sailing Program(23YF1400300)+1 种基金the Fundamental Research Funds for the Central Universities(2232023D-05)the Weiqiao Teaching and Research Innovation Program.
文摘The lack of macro-continuity and mechanical strength of covalent organic frameworks(COFs)has significantly limited their practical applications.Here,we propose an“alcohol-triggered defect cleavage”strategy to precisely regulate the growth and stacking of COF grains through a moderate reversed Schiff base reaction,realizing the direct synthesis of COF nanofibers(CNFs)with high aspect ratio(L/D=103.05)and long length(>20μm).An individual CNF exhibits a biomimetic scale-like architecture,achieving superior flexibility and fatigue resistance under dynamic bending via a multiscale stress dissipation mechanism.Taking advantages of these structural features,we engineer CNF aerogels(CNF-As)with programmable porous structures(e.g.,honeycomb,lamellar,isotropic)via directional ice-template methodology.CNF-As demonstrate 100%COF content,high specific surface area(396.15 m^(2)g^(-1))and superelasticity(~0%elastic deformation after 500 compression cycles at 50%strain),outperforming most COF-based counterparts.Compared with the conventional COF aerogels,the unique structural features of CNF-A enable it to perform outstandingly in uranium extraction,with an 11.72-fold increment in adsorption capacity(920.12 mg g^(-1))and adsorption rate(89.9%),and a 2.48-fold improvement in selectivity(U/V=2.31).This study provides a direct strategy for the development of next-generation COF materials with outstanding functionality and structural robustness.
基金Supported by National Natural Science Foundation of China(Grant Nos.52475035,U23A20615)Zhejiang Provincial Natural Science Foundation of China(Grant No.LMS25E050003)+2 种基金Open Funds of the State Key Laboratory of Fluid Power and Mechatronic Systems at Zhejiang University of China(Grant No.GZKF-202419)Fundamental Research Funds of Zhejiang Sci-Tech University of China(Grant No.24242115-Y)the Zhejiang Provincial General Scientific Research Projects Fund of China(Grant No.Y202353093).
文摘Soft actuators based on cellulose with highly electro-responsive properties have attracted significant attention in the fields of wearable devices,medical and healthcare devices,soft robots,and human-computer interactions.However,existing cellulose-based soft actuators still need to be improved in terms of actuation displacement,bending strain,and driving frequency.Herein,we report a highly responsive ionic actuator using carboxylated cellulose nanofibers from wood pulp(CNFp),graphene nanosheets(GN),and ionic liquids(IL).The CNFp-IL-GN actuator exhibited a large specific capacitance of 749.11 mF/cm^(2)under a 25 mV/s scan rate,a large mechanical displacement(25 mm peak-to-peak)under 2.0 V at 0.1 Hz,a broad actuation frequency(0.1 to 10 Hz),and long working stability.Furthermore,bioinspired applications,including bionic dragonflies and artificial soft-touch fingers,have been demonstrated.These results demonstrate that the proposed actuator is a significant method for advancing soft actuators,artificial muscles,and bioinspired robots.
基金supported by Young Elite Scientists Sponsorship Program by China Association for Science and Technology(No.2022QNRC001)the National Natural Science Foundation of China(No.52273053)the Chenguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission(No.21CGA41)。
文摘Extreme cold weather seriously harms human thermoregulatory system,necessitating high-performance insulating garments to maintain body temperature.However,as the core insulating layer,advanced fibrous materials always struggle to balance mechanical properties and thermal insulation,resulting in their inability to meet the demands for both washing resistance and personal protection.Herein,inspired by the natural spring-like structures of cucumber tendrils,a superelastic and washable micro/nanofibrous sponge(MNFS)based on biomimetic helical fibers is directly prepared utilizing multiple-jet electrospinning technology for high-performance thermal insulation.By regulating the conductivity of polyvinylidene fluoride solution,multiple-jet ejection and multiple-stage whipping of jets are achieved,and further control of phase separation rates enables the rapid solidification of jets to form spring-like helical fibers,which are directly entangled to assemble MNFS.The resulting MNFS exhibits superelasticity that can withstand large tensile strain(200%),1000 cyclic tensile or compression deformations,and retain good resilience even in liquid nitrogen(-196℃).Furthermore,the MNFS shows efficient thermal insulation with low thermal conductivity(24.85 mW m^(-1)K^(-1)),close to the value of dry air,and remains structural stability even after cyclic washing.This work offers new possibilities for advanced fibrous sponges in transportation,environmental,and energy applications.
基金supported by the National Natural Science Foundation of China(Nos.52373280,52177014,51977009,and 52273257).
文摘As electromagnetic(EM)pollution intensifies,EM protection materials have garnered significant attention.However,the development of lightweight and efficient EM protection materials still faces numerous challenges.In this work,a bilayered metal-organic framework(MOF),specifically zeolitic imidazolate framework-8@zeolitic imidazolate framework-67(ZIF-8@ZIF-67),is initially prepared.Subsequently,through a combination of electrospinning and high-temperature carbonization processes,a heterodimensional structure featuring carbon-based dodecahedrons tandemly arranged on carbon nanofibers was obtained.The carbonization at various temperatures modulated the nanofibers'conductive network and graphitization of dodecahedrons,thereby regulating the dielectric response,which is crucial for tuning the EM properties of the material.Furthermore,dielectric-magnetic synergy also plays a certain role in optimizing microwave absorption performance.The Co-CHD@CNF800 with 60 wt%loading content demonstrates a minimum reflection loss(RL)of-53.6 dB at 1.83 mm,while 40 wt%loading content exhibits a maximum effective absorption bandwidth(EAB)of 6 GHz at 2.67 mm.Additionally,Co-CHD@CNF1000 with 80 wt%exhibits remarkable electromagnetic interference(EMI)shielding performance.Importantly,an EM energy conversion device has been constructed that can effectively recover and utilize harmful EM energy.This research presents an innovative approach to the development of lightweight and efficient EM protection materials and devices.
基金financially supported by the Natural Science Foundation of Shandong Province(Nos.ZR2021ME194,2022TSGC2448,and 2023TSGC0545)the Key Technology Research and Development Program of Shandong Province(No.2021ZLGX01).
文摘Carbon-based electromagnetic wave(EMW)absorbing materials attached with metal sulfides famous for good dielectric properties are favored by researchers,which can form heterogeneous interfaces and thus provide supplementary loss mechanisms to make up for the deficiencies of a single material in energy attenuation.Here,Co_(9)S_(8)/Co@coral-like carbon nanofibers(CNFs)/porous carbon hybrids are successfully fabricated by hydrothermal and chemical vapor deposition.The samples have exceptional EMW absorb-ing properties,with a minimum reflection loss of-57.48 dB at a thickness of 2.94 mm and an effective absorption bandwidth of up to 6.10 GHz at only 2.20 mm.The interlocking structure formed by Co@coral-like CNFs,interfacial polarization generated by heterostructure of Co_(9)S_(8),abundant defects and large specific surface area resulted from porous properties are important factors in attaining magnetic-dielectric balance and excellent absorption performance.Different matrixes are selected instead of paraffin to investigate the effect of matrix materials on EMW absorbing capacity.Besides,the EMW attenuation potential for practical applications is also demonstrated by radar cross-section simulations,electric field intensity distribution and power loss density.This work provides a novel strategy for designing outstanding EMW absorbers with unique microstructures using facile and low-cost synthetic routes.
基金Project supported by the STI 2030-Major Projects,China(No.2021ZD0200401)the National Key Research and Development Program of China(No.2023YFF0613000)+1 种基金the National Natural Science Foundation of China(Nos.62222511 and 62175122)the Natural Science Foundation of Zhejiang Province,China(No.LR22F050006)。
文摘Ultrafast fiber lasers are indispensable components in the field of ultrafast optics,and their continuous performance advancements are driving the progress of this exciting discipline.Micro/Nanofibers(MNFs)possess unique properties,such as a large fractional evanescent field,flexible and controllable dispersion,and high nonlinearity,making them highly valuable for generating ultrashort pulses.Particularly,in tasks involving mode-locking and dispersion and nonlinearity management,MNFs provide an excellent platform for investigating intriguing nonlinear dynamics and related phenomena,thereby promoting the advancement of ultrafast fiber lasers.In this paper,we present an introduction to the mode evolution and characteristics of MNFs followed by a comprehensive review of recent advances in using MNFs for ultrafast optics applications including evanescent field modulation and control,dispersion and nonlinear management techniques,and nonlinear dynamical phenomenon exploration.Finally,we discuss the potential application prospects of MNFs in the realm of ultrafast optics.
基金supported by the National Natural Science Foundation of China(51203071,51363014 and 51362018)China Postdoctoral Science Foundation(2014M552509)+2 种基金the Opening Project of State Key Laboratory of Polymer Materials Engineering(Sichuan University)(sklpme2014-4-25)the Program for Hongliu Distinguished Young Scholars in Lanzhou University of Technology(J201402)the University Scientific Research Project of Gansu Province(2014B-025)
文摘Microporous carbon nanofibers (MCNFs) derived from polyacrylonitrile nanofibers were fabricated via electrospinning technology and phase separation in the presence of polyvinylpyrrolidone (PVP). PVP together with a mixed solvent of N, N-Dimethylformamide and dimethyl sulfoxide was used as pore forming agent. The influences of PVP content in casting solution on the structure and electrochemical performance of the MCNFs were also investigated. The highest capacitance of 200 F/g was obtained on a three-electrode system at a scan rate of 0.5 A/g. The good performance was owing to the high specific surface area and the large amount of micro-pores, which enhanced the absorption and the transportation efficiency of electrolyte ion during charge/discharge process. This research indicated that the combination of electrospinning and phase separation technology could be used to fabricate microporous carbon nanofibers as electrode materials for supercapacitors with high specific surface area and outstanding electrochemical performance. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.
基金funding for this work provided by the National Nature Science Foundation of China (51573090)National Key R&D Program of China (2016YFB0302000)Open Foundation from State Key Laboratory of Fluorinated Functional Membrane Material
文摘Currently, the oxygen reduction reaction(ORR) mainly depends on precious metal platinum(Pt) catalysts. However, Pt-based catalysts have several shortcomings, such as high cost, scarcity, and poor long-term stability. Therefore, development of e cient metal-free electrocatalysts to replace Pt-based electrocatalysts is important. In this study, we successfully prepared nitrogen-and fluorinecodoped microporous carbon nanofibers(N, F-MCFs) via electrospinning polyacrylonitrile/polyvinylidene fluoride/polyvinylpyrrolidone(PAN/PVDF/PVP) tricomponent polymers followed by a hydrothermal process and thermal treatment, which was achieved for the first time in the literature. The results indicated that N, F-MCFs exhibit a high catalytic activity(E_(onset): 0.94 V vs. RHE, E_(1/2): 0.81 V vs. RHE, and electron transfer number: 4.0) and considerably better stability and methanol tolerance for ORR in alkaline solutions as compared to commercial Pt/carbon(Pt/C, 20 wt%) catalysts. Furthermore, in acidic media, N, F-MCFs showed a four-electron transfer pathway for ORR. This study provides a new strategy for in situ synthesis of N, F-MCFs as highly e cient metal-free electrocatalysts for ORR in fuel cells.
基金financially supported by the Natural Science Foundation of Shandong Province (No. ZR2019YQ24)Taishan Scholars and Young Experts Program of Shandong Province (No.tsqn202103057)+1 种基金the Qingchuang Talents Induction Program of Shandong Higher Education Institution (Research and Innovation Team of Structural-Functional Polymer Composites)Special Financial of Shandong Province (Structural Design of High-efficiency Electromagnetic Wave-absorbing Composite Materials and Construction of Shandong Provincial Talent Teams)
文摘Application of novel radio technologies and equip-ment inevitably leads to electromagnetic pollution.One-dimensional polymer-based composite membrane structures have been shown to be an effective strategy to obtain high-performance microwave absorbers.Herein,we reported a one-dimensional N-doped carbon nanofibers material which encapsulated the hollow Co_(3)SnC_(0.7) nano-cubes in the fiber lumen by electrospinning.Space charge stacking formed between nanoparticles can be channeled by longitudinal fibrous structures.The dielectric constant of the fibers is highly related to the carbonization temperature,and the great impedance matching can be achieved by synergetic effect between Co_(3)SnC_(0.7) and carbon network.At 800℃,the necklace-like Co_(3)SnC_(0.7)/CNF with 5%low load achieves an excellent RL value of−51.2 dB at 2.3 mm and the effective absorption bandwidth of 7.44 GHz with matching thickness of 2.5 mm.The multiple electromagnetic wave(EMW)reflections and interfacial polarization between the fibers and the fibers internal contribute a major effect to attenuating the EMW.These strategies for regulating electromagnetic performance can be expanded to other electromagnetic functional materials which facilitate the development of emerging absorbers.
基金the financial support received from Silpakorn University Research and Development Institutesupported by the Higher Education Re-search Promotion and National Research University Project of Thailand,Office of the Higher Education Commission(2559A11462006)Faculty of Pharmacy,Silpakorn Univer-sity
文摘The aim of this study was to elucidate the optimized fabrication factors influencing the formation and properties of shellac(SHL) nanofibers loaded with an antimicrobial monolaurin(ML). The main and interaction effects of formulation and process parameters including SHL content(35%–40% w/w), ML content(1%–3% w/w), applied voltage(9–27 kV) and flow rate(0.4–1.2 ml/h) on the characteristic of nanofibers were investigated through a total of 19 experiments based on a full factorial design with three replicated center points. As a result, the SHL content was the major parameter affecting fiber diameter. Another response result revealed that the SHL content would be also the most significant negative impact on amount of beads. An increase in the concentration of SHL leaded to a reduction in the amount of beads. From the results of characterization study, it was proved that ML might be entrapped between the chains of SHL during the electrospinning process exhibiting an excellent encapsulation. According to the response surface area, small(?488 nm) and beadless(?0.48) fibers were obtained with the SHL and ML contents of 37.5% and 1.1% w/w respectively, at the applied voltage of 18 k V and the flow rate of 0.8 ml/h. In addition, the results of the kill-kinetic studies showed that SHL nanofibers loaded with ML exhibited an excellent antibacterial activity against Staphylococcus aureus, while Escherichia coli was less affected due to the hydrophilic structure of the its outer membrane. ML also exerted an antifun-gal activity by reducing the number of Candida albicans colonies. Based on their structural and antimicrobial properties, SHL nanofibers containing ML could be potentially used as a medicated dressing for wound treatment.
基金This work was supported by the National Natural Science Foundation of China(No.50171063,20003009)Zhejang Provincial Natural Science Foundation(No.200053).
文摘Platinum nanoparticles supported on graphite nanofibers (GNFs) were prepared bymicrowave assistant heating polyol process. TEM images showed that microwave prepared Ptnanoparticles supported on GNFs were small and uniform, and the average diameter was about 3.4nm. Cyclic voltammetric test showed that Pt/GNFs exhibited very high electrocatalytic activity formethanol oxidation.
基金supported by the National Natural Science Foundation of China(No.22278260)the Open Foundation of Key Laboratory of Auxiliary Chemistry and Technology for Chemical Industry(No.KFKT2021-14)Shaanxi Collaborative Innovation Center of Industrial Auxiliary Chemistry and Technology(No.KFKT2021-14).
文摘Aramid papers (AP), made of aramid fibers, demonstrate superiority in electrical insulation applications. Unfortunately, the strength and electrical insulating properties of AP remain suboptimal, primarily due to the smooth surface and chemical inertness of aramid fibers. Herein, AP are modified via the nacre-mimetic structure composed of aramid nanofibers (ANF) and carbonylated basalt nanosheets (CBSNs). This is achieved by impregnating AP into an ANF-CBSNs (A-C) suspension containing a 3D ANF framework as the matrix and 2D CBSNs as fillers. The resultant biomimetic composite papers (AP/A-C composite papers) exhibit a layered “brick-and-mortar” structure, demonstrating superior mechanical and electrical insulating properties. Notably, the tensile strength and breakdown strength of AP/A-C5 composite papers reach 39.69 MPa and 22.04 kV mm^(−1), respectively, representing a 155 % and 85 % increase compared to those of the control AP. These impressive properties are accompanied with excellent volume resistivity, exceptional dielectric properties, impressive folding endurance, outstanding heat insulation, and remarkable flame retardance. The nacre-inspired strategy offers an effective approach for producing highly promising electrical insulating papers for advanced electrical equipment.
基金Project(12JJ6051) supported by the Natural Science Foundation of Hunan Province,ChinaProject(2011CB605806) supported by the National Basic Research Program of China
文摘Before densification by chemical vapor infiltration,carbon or SiC nanofibers were grown on the surface of carbon fibers by catalytic chemical vapor deposition using electroplated Ni as catalyst.The modification and mechanism of nanofibers on the pyrocarbon deposition during chemical vapor infiltration were investigated.The results show that the nanofibers improve the surface activity of the carbon fibers and become active nucleation centers during chemical vapor infiltration.They can induce the ordered deposition of pyrocarbon and adjust the interface bonding between pyrocarbon and carbon fibers during the infiltration.
基金financially supported by the National Natural Science Foundation of China (No. 22225902, U22A20436, 22209185)National Key Research&Development Program of China (2022YFE0115900, 2023YFA1507101, 2021YFA1501500)+1 种基金the Self-deployment Project Research Program of Haixi Institutes,Chinese Academy of Sciences (No. CXZX-2022-GH04, CXZX-2023-JQ08)Science and Technology Program of Fuzhou (2023-P-009)。
文摘Manganese-based chalcogenides have significant potential as anodes for sodium-ion batteries(SIBs) due to their high theoretical specific capacity, abundant natural reserves, and environmental friendliness. However, their application is hindered by poor cycling stability, resulting from severe volume changes during cycling and slow reaction kinetics due to their complex crystal structure. Here, an efficient and straightforward strategy was employed to in-situ encapsulate single-phase porous nanocubic MnS_(0.5)Se_(0.5) into carbon nanofibers using electrospinning and the hard template method, thus forming a necklace-like porous MnS_(0.5)Se_(0.5)-carbon nanofiber composite(MnS_(0.5)Se_(0.5)@N-CNF). The introduction of Se significantly impacts both the composition and microstructure of MnS_(0.5)Se_(0.5), including lattice distortion that generates additional defects, optimization of chemical bonds, and a nano-spatially confined design. In situ/ex-situ characterization and density functional theory calculations verified that this MnS_(0.5)Se_(0.5)@N-CNF allevi- ates the volume expansion and facilitates the transfer of Na+/electron. As expected, MnS_(0.5)Se_(0.5)@N-CNF anode demonstrates excellent sodium storage performance, characterized by high initial Coulombic efficiency(90.8%), high-rate capability(370.5 m Ahg^(-1) at 10 Ag^(-1)) and long durability(over 5000 cycles at 5 Ag^(-1)). The MnS_(0.5)Se_(0.5)@N-CNF//NVP@C full cell, assembled with MnS_(0.5)Se_(0.5)@N-CNF as anode and Na_(3)V_(2)(PO_4)_(3)@C as cathode, exhibits a high energy density of 254 Wh kg^(-1) can be provided. This work presents a novel strategy to optimize the design of anode materials through structural engineering and Se substitution, while also elucidating the underlying reaction mechanisms.
