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
Exploration of advanced gel polymer electrolytes(GPEs)represents a viable strategy for mitigating dendritic lithium(Li)growth,which is crucial in ensuring the safe operation of high energy density Li metal batteries(L...Exploration of advanced gel polymer electrolytes(GPEs)represents a viable strategy for mitigating dendritic lithium(Li)growth,which is crucial in ensuring the safe operation of high energy density Li metal batteries(LMBs).Despite this,the application of GPEs is still hindered by inadequate ionic conductivity,low Li^(+)transference number,and subpar physicochemical properties.Herein,Ti O_(2-x)nanofibers(NF)with oxygen vacancy defects were synthesized by a one-step process as inorganic fillers to enhance the thermal/mechanical/ionic-transportation performances of composite GPEs.Various characterizations and theoretical calculations reveal that the oxygen vacancies on the surface of Ti O_(2-x)NF accelerate the dissociation of Li PF_6,promote the rapid transfer of free Li^(+),and influence the formation of Li F-enriched solid electrolyte interphase.Consequently,the composite GPEs demonstrate enhanced ionic conductivity(1.90m S cm^(-1)at room temperature),higher lithium-ion transference number(0.70),wider electrochemical stability window(5.50 V),superior mechanical strength,excellent thermal stability(210℃),and improved compatibility with lithium,resulting in superior cycling stability and rate performance in both Li||Li,Li||Li Fe PO_(4),and Li||Li Ni_(0.8)Co_(0.1)Mn_(0.1)O_(2)cells.Overall,the synergistic influence of nanofiber morphology and enriched oxygen vacancy structure of fillers on electrochemical properties of composite GPEs is comprehensively investigated,thus,it is anticipated to shed new light on designing high-performance GPEs LMBs.展开更多
Achieving the detachment of divertor can help to alleviate excessive heat load and sputtering problems on the target plates,thereby extending the lifetime of divertor components for fusion devices.In order to provide ...Achieving the detachment of divertor can help to alleviate excessive heat load and sputtering problems on the target plates,thereby extending the lifetime of divertor components for fusion devices.In order to provide a fast but relatively reliable prediction of plasma parameters along the flux tube for future device design,a one-dimensional(1D)modeling code for the operating point of impurity seeded detached divertor is developed based on Python language,which is a fluid model based on previous work(Plasma Phys.Control.Fusion 58045013(2016)).The experimental observation of the onset of divertor detachment by neon(Ne)and argon(Ar)seeding in EAST is well reproduced by using the 1D modeling code.The comparison between the 1D modeling and two-dimensional(2D)simulation by the SOLPS-ITER code for CFETR detachment operation with Ne and Ar seeding also shows that they are in good agreement.We also predict the radiative power loss and corresponding impurity concentration requirement for achieving divertor detachment via different impurity seeding under high heating power conditions in EAST and CFETR phase II by using the 1D model.Based on the predictions,the optimized parameter space for divertor detachment operation on EAST and CFETR is also determined.Such a simple but reliable 1D model can provide a reasonable parameter input for a detailed and accurate analysis by 2D or three-dimensional(3D)modeling tools through rapid parameter scanning.展开更多
Roxarsone(ROX)is a commonly used antibacterial and growth-promoting additive to animal feed.The development of an effective method for detecting ROX and its conversion products is of importance because of their potent...Roxarsone(ROX)is a commonly used antibacterial and growth-promoting additive to animal feed.The development of an effective method for detecting ROX and its conversion products is of importance because of their potential harm to human health and ecosystem.Herein,we report the designed synthesis of a novel one-dimensional covalent organic framework(1D COF),named EP-COF,and its application as a fluorescent probe for ROX sensing.EP-COF is constructed based on imine linkages,exhibiting high crystallinity,strong fluorescence emission,and good dispersibility in water.It displays a remarkable capability to efficiently detect ROX,with an impressive detection limit of 4.5 nmol/L.Moreover,EP-COF also offers advantages of excellent selectivity,and high structural stability.This work not only presents a promising approach for the detection of harmful substances like ROX,but also serves as a valuable reference for exploring application of 1D COFs in chemical sensing.展开更多
This work presents the development of hierarchical niobium pentoxide(Nb_(2)O_(5))-based composite nanofiber membranes for integrated adsorption and photocatalytic degradation of methylene blue(MB)pollutants from aqueo...This work presents the development of hierarchical niobium pentoxide(Nb_(2)O_(5))-based composite nanofiber membranes for integrated adsorption and photocatalytic degradation of methylene blue(MB)pollutants from aqueous solutions.The Nb_(2)O_(5) nanorods were vertically grown using a hydrothermal process on a base electrospun nanofibrous membrane made of polyacrylonitrile/polyvinylidene fluoride/ammonium niobate(V)oxalate hydrate(Nb_(2)O_(5)@PAN/PVDF/ANO).They were characterized using field-emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD)analysis,and Fourier transform infrared(FTIR)spectroscopy.These composite nanofibers possessed a narrow optical bandgap energy of 3.31 eV and demonstrated an MB degradation efficiency of 96%after 480 min contact time.The pseudo-first-order kinetic study was also conducted,in which Nb_(2)O_(5)@PAN/PVDF/ANO nanofibers have kinetic constant values of 1.29×10^(-2) min^(-1) and 0.30×10^(-2) min^(-1) for adsorption and photocatalytic degradation of MB aqueous solutions,respectively.These values are 17.7 and 7.8 times greater than those of PAN/PVDF/ANO nanofibers without Nb_(2)O_(5) nanostructures.Besides their outstanding photocatalytic performance,the developed membrane materials exhibit advantageous characteristics in recycling,which subsequently widen their practical use in environmental remediation applications.展开更多
In this paper,numerical experiments are carried out to investigate the impact of penalty parameters in the numerical traces on the resonance errors of high-order multiscale discontinuous Galerkin(DG)methods(Dong et al...In this paper,numerical experiments are carried out to investigate the impact of penalty parameters in the numerical traces on the resonance errors of high-order multiscale discontinuous Galerkin(DG)methods(Dong et al.in J Sci Comput 66:321–345,2016;Dong and Wang in J Comput Appl Math 380:1–11,2020)for a one-dimensional stationary Schrödinger equation.Previous work showed that penalty parameters were required to be positive in error analysis,but the methods with zero penalty parameters worked fine in numerical simulations on coarse meshes.In this work,by performing extensive numerical experiments,we discover that zero penalty parameters lead to resonance errors in the multiscale DG methods,and taking positive penalty parameters can effectively reduce resonance errors and make the matrix in the global linear system have better condition numbers.展开更多
The unique characteristics of nanofibers in rational electrode design enable effec-tive utilization and maximizing material properties for achieving highly efficient and sustainable CO_(2) reduction reactions( CO_(2)R...The unique characteristics of nanofibers in rational electrode design enable effec-tive utilization and maximizing material properties for achieving highly efficient and sustainable CO_(2) reduction reactions( CO_(2)RRs)in solid oxide elec-trolysis cells(SOECs).However,practical appli-cation of nanofiber-based electrodes faces chal-lenges in establishing sufficient interfacial contact and adhesion with the dense electrolyte.To tackle this challenge,a novel hybrid nanofiber electrode,La_(0.6)Sr_(0.4)Co_(0.15)Fe_(0.8)Pd_(0.05)O_(3-δ)(H-LSCFP),is developed by strategically incorporating low aspect ratio crushed LSCFP nanofibers into the excess porous interspace of a high aspect ratio LSCFP nanofiber framework synthesized via electrospinning technique.After consecutive treatment in 100% H_(2) and CO_(2) at 700°C,LSCFP nanofibers form a perovskite phase with in situ exsolved Co metal nanocatalysts and a high concentration of oxygen species on the surface,enhancing CO_(2) adsorption.The SOEC with the H-LSCFP electrode yielded an outstanding current density of 2.2 A cm^(-2) in CO_(2) at 800°C and 1.5 V,setting a new benchmark among reported nanofiber-based electrodes.Digital twinning of the H-LSCFP reveals improved contact adhesion and increased reaction sites for CO_(2)RR.The present work demonstrates a highly catalytically active and robust nanofiber-based fuel electrode with a hybrid structure,paving the way for further advancements and nanofiber applications in CO_(2)-SOECs.展开更多
Highly dispersed bimetallic alloy nanoparticle electrocatalysts have been demonstrated to exhibit exceptional performance in driving the nitrate reduction reaction(NO_(3)RR)to generate ammonia(NH_(3)).In this study,we...Highly dispersed bimetallic alloy nanoparticle electrocatalysts have been demonstrated to exhibit exceptional performance in driving the nitrate reduction reaction(NO_(3)RR)to generate ammonia(NH_(3)).In this study,we prepared mesoporous carbon nanofibers(mCNFs)functionalized with ordered PtFe alloys(O-PtFe-mCNFs)by a composite micelle interface-induced co-assembly method using poly(ethylene oxide)-block-polystyrene(PEO-b-PS)as a template.When employed as electrocatalysts,O-PtFe-mCNFs exhibited superior electrocatalytic performance for the NO_(3RR)compared to the mCNFs functionalized with disordered PtFe alloys(D-PtFe-mCNFs).Notably,the NH_(3)production performance was particularly outstanding,with a maximum NH_(3)yield of up to 959.6μmol/(h·cm~2).Furthermore,the Faraday efficiency(FE)was even 88.0%at-0.4 V vs.reversible hydrogen electrode(RHE).This finding provides compelling evidence of the potential of ordered PtFe alloy catalysts for the electrocatalytic NO_(3)RR.展开更多
Copper-based nanomaterials have been widely used in catalysis,electrodes,and other applications due to their unique electron-transfer properties.In this work,an efficient electrochemical sensor based on an electrode m...Copper-based nanomaterials have been widely used in catalysis,electrodes,and other applications due to their unique electron-transfer properties.In this work,an efficient electrochemical sensor based on an electrode modified with one-dimensional Cu(OH)_(2)/carboxymethyl cellulose(CMC)composite nanofibers was fabricated and investigated for the detection of aspirin.Scanning electron microscopy was employed to examine the morphological characteristics of these composite nanofibers.Cyclic voltammetry and electrochemical impedance spectroscopy were used to assess the electrochemical performance of a Cu(OH)_(2)/CMC composite nanofiber-modified electrode.The findings indicate that the modified electrode has a very high sensitivity to aspirin.The observed enhanced performance could be a result of the high surface-to-volume ratio of the composite nanofibers and their superior electron-transport characteristics,which may hasten electron transfer between aspirin and the surfaces of the modified electrode.This detection technique also demonstrated strong selectivity for aspirin.These findings imply that the technique can be applied as a highly effective and selective approach to aspirin measurement in biological science.展开更多
The rational synergy of chemical composition and spatial nanostructures of electrode materials play important roles in high-performance energy storage devices.Here,we designed pea-like MoS_(2)@NiS_(1.03)-carbon hollow...The rational synergy of chemical composition and spatial nanostructures of electrode materials play important roles in high-performance energy storage devices.Here,we designed pea-like MoS_(2)@NiS_(1.03)-carbon hollow nanofibers using a simple electrospinning and thermal treatment method.The hierarchical hollow nanofiber is composed of a nitrogen-doped carbon-coated NiS_(1.03) tube wall,in which pea-like uniformly discrete MoS_(2) nanoparticles are enclosed.As a sodium-ion battery electrode material,the MoS_(2)@NiS_(1.03)-carbon hollow nanofibers have abundant diphasic heterointerfaces,a conductive network,and appropriate volume variation-buffering spaces,which can facilitate ion diffusion kinetics,shorten the diffusion path of electrons/ion,and buffer volume expansion during Na^(+)insertion/extraction.It shows outstanding rate capacity and long-cycle performance in a sodium-ion battery.This heterogeneous hollow nanoarchitectures designing enlightens an efficacious strategy to boost the capacity and long-life stability of sodium storage performance of electrode materials.展开更多
Hydrogen sulfide(H_(2)S)is an industrial exhausted gas that is highly toxic to humans and the environment.Combining desulfurization and fabrication of cathode materials for lithium-sulfur batteries(LSBs)can solve this...Hydrogen sulfide(H_(2)S)is an industrial exhausted gas that is highly toxic to humans and the environment.Combining desulfurization and fabrication of cathode materials for lithium-sulfur batteries(LSBs)can solve this issue with a double benefit.Herein,the amino-functionalized lotus root-like carbon nanofibers(NH_(2)-PLCNFs)are prepared by the amination of electrospinning carbon nanofibers under dielectric barrier discharge plasma.Selective catalytic oxidation of H_(2)S to elemental sulfur(S)is achieved over the metalfree NH_(2)-PLCNFs catalyst,and the obtained composite S@NH_(2)-PLCNFs is further used as cathode in LSBs.NH_(2)-PLCNFs enable efficient desulfurization(removal capacity as high as 3.46 g H_(2)S g^(−1) catalyst)and strongly covalent stabilization of S on modified carbon nanofibers.LSBs equipped with S@NH_(2)-PLCNFs deliver a high specific capacity of 705.8 mA h g^(−1) at 1 C after 1000 cycles based on the spatial confinement and the covalent stabilization of electroactive materials on amino-functionalized porous carbon matrix.It is revealed that S@NH_(2)-PLCNFs obtained by this kind of chemical vapor deposition leads to a more homogeneous S distribution and superior electrochemical performance to the sample S/NH_(2)-PLCNF-M prepared by the traditional molten infusion.This work opens a new avenue for the combination of environment protection and energy storage.展开更多
OER catalyst of Ni_(3)Fe/Ni_(4)S_(3)/Ni/C(NiFeSC series)mixed crystal composite nanofibers was prepared by electrospinning and atmospheric heat treatment process.The testing results indicate that the diameters of Ni_(...OER catalyst of Ni_(3)Fe/Ni_(4)S_(3)/Ni/C(NiFeSC series)mixed crystal composite nanofibers was prepared by electrospinning and atmospheric heat treatment process.The testing results indicate that the diameters of Ni_(3)Fe/Ni_(4)S_(3)/Ni/C composite nanofibers is about 200 nm,the grains size is about 1-3 nm,and the fiber surface is rough.The electrochemical test results show that the heterojunction of the prepared Ni_(3)Fe/Ni_(4)S_(3)/Ni/C hybrid crystal composite nanofiber has synergistic effect with sulfide,and exhibits good electrocatalytic activity of water decomposition and OER in alkaline system.The OER electrocatalytic performance of Ni_(3)Fe/Ni_(4)S_(3)/Ni/C composite electrode prepared via a heat treatment at 1000℃process was tested in 1 mol/L KOH electrolytes.The results show that the overpotential is about 298 mV,the Tafel slope is about 74 mV?dec-1,and the surface resistance is about 1.69Ω·cm^(2),at the current density of 10 mA·cm^(-2).展开更多
Recently,food grade nanofiber-based materials have received growing attentions in food packaging.In this work,novel active and intelligent packaging nanofibers based on gelatin/chitosan with curcumin(GA/CS/CUR)were de...Recently,food grade nanofiber-based materials have received growing attentions in food packaging.In this work,novel active and intelligent packaging nanofibers based on gelatin/chitosan with curcumin(GA/CS/CUR)were developed via electrospinning technique.Effects of the incorporation of CUR content(0.1%-0.3%,m/m)on the microstructure and functional properties of the electrospun nanofibers were investigated.Morphological studies using scanning electron microscopy indicated that loading CUR can affect the average diameter of nanofiber mats,which remained around 160-180 nm.The addition of an appropriate level CUR(0.2%,m/m)led to a stronger intermolecular interaction,and thus enhanced the thermal stability and tensile strength of the obtained nanofibers.Meanwhile,the incorporation of CUR significantly improved antioxidant activity and the antimicrobial activity of GA/CS/CUR nanofibers.Moreover,the sensitivity of nanofibers to ammonia results indicated that GA/CS nanofibers containing 0.2%CUR(GA/CS/CURⅡ)presented high sensitivity of colorimetric behavior to ammonia(within 3 min).These results suggest GA/CS/CURⅡnanofibers has great potential as a multifunctional packaging to protect and monitor the freshness of proteinrich animal foods,such as meat and seafood.展开更多
Bamboo fibers(BFs),with features of renewability and biodegradability,have been widely used in paper-making products.In order to improve the mechanical properties and water absorption behaviors of the BF paper,bacteri...Bamboo fibers(BFs),with features of renewability and biodegradability,have been widely used in paper-making products.In order to improve the mechanical properties and water absorption behaviors of the BF paper,bacterial cellulose nanofibers(BCNFs)as environmentally friendly nano-fibrillated cellulose(NFC)were combined with BFs.The structures and properties of the BF/BCNF composite paper were characterized by field emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD),Fourier transforms infrared(FTIR)spectroscopy,mechanical tests,pore size tests,and water absorption tests.The results indicated that the addition of BCNFs could significantly improve the water absorption capacity and mechanical properties.The water absorption ratio of the BF/BCNF composite paper with a BCNF mass fraction of 9%comes to 443%,about 1.33 times that of the pure BF paper.At the same BCNF content,the tensile strength of the BF/BCNF composite paper in dry and wet states was 12.37 MPa and 200.9 kPa,respectively,increasing by 98.24%and 136.91%as compared with that of the BF paper.展开更多
Upregulation of vascular endothelial growth factor A/basic fibroblast growth factor(VEGFA/b FGF)expression in the penumbra of cerebral ischemia can increase vascular volume,reduce lesion volume,and enhance neural cell...Upregulation of vascular endothelial growth factor A/basic fibroblast growth factor(VEGFA/b FGF)expression in the penumbra of cerebral ischemia can increase vascular volume,reduce lesion volume,and enhance neural cell proliferation and differentiation,thereby exerting neuroprotective effects.However,the beneficial effects of endogenous VEGFA/b FGF are limited as their expression is only transiently increased.In this study,we generated multilayered nanofiber membranes loaded with VEGFA/b FGF using layer-by-layer self-assembly and electrospinning techniques.We found that a membrane containing 10 layers had an ideal ultrastructure and could efficiently and stably release growth factors for more than 1 month.This 10-layered nanofiber membrane promoted brain microvascular endothelial cell tube formation and proliferation,inhibited neuronal apoptosis,upregulated the expression of tight junction proteins,and improved the viability of various cellular components of neurovascular units under conditions of oxygen/glucose deprivation.Furthermore,this nanofiber membrane decreased the expression of Janus kinase-2/signal transducer and activator of transcription-3(JAK2/STAT3),Bax/Bcl-2,and cleaved caspase-3.Therefore,this nanofiber membrane exhibits a neuroprotective effect on oxygen/glucose-deprived neurovascular units by inhibiting the JAK2/STAT3 pathway.展开更多
Searching for one-dimensional(1D)nanostructure with ferromagnetic(FM)half-metallicity is of significance for the development of miniature spintronic devices.Here,based on the first-principles calculations,we propose t...Searching for one-dimensional(1D)nanostructure with ferromagnetic(FM)half-metallicity is of significance for the development of miniature spintronic devices.Here,based on the first-principles calculations,we propose that the 1D CrN nanostructure is a FM half-metal,which can generate the fully spin-polarized current.The ab initio molecular dynamic simulation and the phonon spectrum calculation demonstrate that the 1D CrN nanostructure is thermodynamically stable.The partially occupied Cr-d orbitals endow the nanostructure with FM half-metallicity,in which the half-metallic gap(?s)reaches up to 1.58 eV.The ferromagnetism in the nanostructure is attributed to the superexchange interaction between the magnetic Cr atoms,and a sizable magnetocrystalline anisotropy energy(MAE)is obtained.Moreover,the transverse stretching of nanostructure can effectively modulate?s and MAE,accompanied by the preservation of half-metallicity.A nanocable is designed by encapsulating the CrN nanostructure with a BN nanotube,and the intriguing magnetic and electronic properties of the nanostructure are retained.These novel characteristics render the 1D CrN nanostructure as a compelling candidate for exploiting high-performance spintronic devices.展开更多
The degree of polymer chain orientation is a key structural parameter that determines the mechanical and physical properties of fibers.However,understanding and significantly tuning the orientation of fiber macromolec...The degree of polymer chain orientation is a key structural parameter that determines the mechanical and physical properties of fibers.However,understanding and significantly tuning the orientation of fiber macromolecular chains remain elusive.Herein,we propose a novel electrospinning technique that can efficiently modulate molecular chain orientation by controlling the electric field.In contrast to the typical electrospinning method,this technique can piecewise control the electric field by applying high voltage to the metal ring instead of the needle.Benefiting from this change,a new electric field distribution can be realized,leading to a non-monotonic change in the drafting force.As a result,the macromolecular chain orientation of polyethylene oxide(PEO)nanofibers was significantly improved with a recordhigh infrared dichroic ratio.This was further confirmed by the sharp decrease in the PEO jet fineness of approximately 80%and the nanofiber diameter from 298 to 114 nm.Interestingly,the crystallinity can also be adjusted,with an obvious drop from 74.9%to 31.7%,which is different from the high crystallinity caused by oriented chains in common materials.This work guides a new perspective for the preparation of advanced electrospun nanofibers with optimal orientation–crystallinity properties,a merited feature for various applications.展开更多
Photoreforming hydrogen evolution(Pr-HE)of a water-pollutant system could simultaneously achieve efficient hydrogen production and pollutant degradation.It provides a new way to solve energy and environmental issues,b...Photoreforming hydrogen evolution(Pr-HE)of a water-pollutant system could simultaneously achieve efficient hydrogen production and pollutant degradation.It provides a new way to solve energy and environmental issues,but the poor internal charge separation still limits its performance.This work designed hetero-Janus nanofibers(HJNFs)with ordered electric field distribution and separated redox surfaces to promote Pr-HE of the water-pollutant system.Taking ZnO/NiO heterojunction as an example,the hetero-Janus structures were prepared via"Dual-channel"electrospinning and further confirmed by the element morphology analysis and asymmetric distribution of the XPS spectra.The theoretical simulation showed that Janus structures could effectively inhibit the electron trap and hole trap generation,then accelerate the directional carrier migration to the surface.Experimental investigations also confirmed that Janus structures could effectively suppress internal exciton luminescence and accelerate surface charge transfer.The Pr-HE amount and the corresponding propranolol(PRO)degradation rate of HJNFs were 7.9 and 1.5 times higher than hetero-mixed nanofibers(HMNFs).The enhancement factor of Pr-HE in water-PRO to pure water was about 3.1,but nearly zero for HMNFs.This prominent synergistic effect was due to the enhancement of charge separation and the inhibition of cascade side reaction from hetero-Janus structures.Furthermore,the synchronous Pr-HE and degradation reactions were significantly promoted by selective introducing Ag nanoparticles in one side of the HJNFs for enlarging the interfacial Fermi energy level difference.The hetero-Janus strategy offers a new perspective on designing efficient photoreforming photocatalysts for energy and environment applications.展开更多
A lightweight flexible thermally stable composite is fabricated by com-bining silica nanofiber membranes(SNM)with MXene@c-MWCNT hybrid film.The flexible SNM with outstanding thermal insulation are prepared from tetrae...A lightweight flexible thermally stable composite is fabricated by com-bining silica nanofiber membranes(SNM)with MXene@c-MWCNT hybrid film.The flexible SNM with outstanding thermal insulation are prepared from tetraethyl orthosilicate hydrolysis and condensation by electrospinning and high-temperature calcination;the MXene@c-MWCNT_(x:y)films are prepared by vacuum filtration tech-nology.In particular,the SNM and MXene@c-MWCNT_(6:4)as one unit layer(SMC_(1))are bonded together with 5 wt%polyvinyl alcohol(PVA)solution,which exhibits low thermal conductivity(0.066 W m^(-1)K^(-1))and good electromagnetic interference(EMI)shielding performance(average EMI SE_(T),37.8 dB).With the increase in func-tional unit layer,the overall thermal insulation performance of the whole composite film(SMC_(x))remains stable,and EMI shielding performance is greatly improved,especially for SMC_(3)with three unit layers,the average EMI SET is as high as 55.4 dB.In addition,the organic combination of rigid SNM and tough MXene@c-MWCNT_(6:4)makes SMC_(x)exhibit good mechanical tensile strength.Importantly,SMC_(x)exhibit stable EMI shielding and excellent thermal insulation even in extreme heat and cold environment.Therefore,this work provides a novel design idea and important reference value for EMI shielding and thermal insulation components used in extreme environmental protection equipment in the future.展开更多
The oxygen reduction reaction(ORR)electrocatalytic activity of Pt-based catalysts can be significantly improved by supporting Pt and its alloy nanoparticles(NPs)on a porous carbon support with large surface area.Howev...The oxygen reduction reaction(ORR)electrocatalytic activity of Pt-based catalysts can be significantly improved by supporting Pt and its alloy nanoparticles(NPs)on a porous carbon support with large surface area.However,such catalysts are often obtained by constructing porous carbon support followed by depositing Pt and its alloy NPs inside the pores,in which the migration and agglomeration of Pt NPs are inevitable under harsh operating conditions owing to the relatively weak interaction between NPs and carbon support.Here we develop a facile electrospinning strategy to in-situ prepare small-sized PtZn NPs supported on porous nitrogen-doped carbon nanofibers.Electrochemical results demonstrate that the as-prepared PtZn alloy catalyst exhibits excellent initial ORR activity with a half-wave potential(E_(1/2))of 0.911 V versus reversible hydrogen electrode(vs.RHE)and enhanced durability with only decreasing 11 mV after 30,000 potential cycles,compared to a more significant drop of 24 mV in E_(1/2)of Pt/C catalysts(after 10,000 potential cycling).Such a desirable performance is ascribed to the created triple-phase reaction boundary assisted by the evaporation of Zn and strengthened interaction between nanoparticles and the carbon support,inhibiting the migration and aggregation of NPs during the ORR.展开更多
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supported by the National Natural Science Foundation of China(52122702,52277215)the Natural Science Foundation of Heilongjiang Province of China(JQ2021E005)。
文摘Exploration of advanced gel polymer electrolytes(GPEs)represents a viable strategy for mitigating dendritic lithium(Li)growth,which is crucial in ensuring the safe operation of high energy density Li metal batteries(LMBs).Despite this,the application of GPEs is still hindered by inadequate ionic conductivity,low Li^(+)transference number,and subpar physicochemical properties.Herein,Ti O_(2-x)nanofibers(NF)with oxygen vacancy defects were synthesized by a one-step process as inorganic fillers to enhance the thermal/mechanical/ionic-transportation performances of composite GPEs.Various characterizations and theoretical calculations reveal that the oxygen vacancies on the surface of Ti O_(2-x)NF accelerate the dissociation of Li PF_6,promote the rapid transfer of free Li^(+),and influence the formation of Li F-enriched solid electrolyte interphase.Consequently,the composite GPEs demonstrate enhanced ionic conductivity(1.90m S cm^(-1)at room temperature),higher lithium-ion transference number(0.70),wider electrochemical stability window(5.50 V),superior mechanical strength,excellent thermal stability(210℃),and improved compatibility with lithium,resulting in superior cycling stability and rate performance in both Li||Li,Li||Li Fe PO_(4),and Li||Li Ni_(0.8)Co_(0.1)Mn_(0.1)O_(2)cells.Overall,the synergistic influence of nanofiber morphology and enriched oxygen vacancy structure of fillers on electrochemical properties of composite GPEs is comprehensively investigated,thus,it is anticipated to shed new light on designing high-performance GPEs LMBs.
基金Project supported by the National Key Research and Development Program of China (Grant No.2022YFE03030001)the National Natural Science Foundation of China (Grant No.12075283)。
文摘Achieving the detachment of divertor can help to alleviate excessive heat load and sputtering problems on the target plates,thereby extending the lifetime of divertor components for fusion devices.In order to provide a fast but relatively reliable prediction of plasma parameters along the flux tube for future device design,a one-dimensional(1D)modeling code for the operating point of impurity seeded detached divertor is developed based on Python language,which is a fluid model based on previous work(Plasma Phys.Control.Fusion 58045013(2016)).The experimental observation of the onset of divertor detachment by neon(Ne)and argon(Ar)seeding in EAST is well reproduced by using the 1D modeling code.The comparison between the 1D modeling and two-dimensional(2D)simulation by the SOLPS-ITER code for CFETR detachment operation with Ne and Ar seeding also shows that they are in good agreement.We also predict the radiative power loss and corresponding impurity concentration requirement for achieving divertor detachment via different impurity seeding under high heating power conditions in EAST and CFETR phase II by using the 1D model.Based on the predictions,the optimized parameter space for divertor detachment operation on EAST and CFETR is also determined.Such a simple but reliable 1D model can provide a reasonable parameter input for a detailed and accurate analysis by 2D or three-dimensional(3D)modeling tools through rapid parameter scanning.
基金the Science and Technology Commission of Shanghai Municipality(No.20JC1415400)for financial support。
文摘Roxarsone(ROX)is a commonly used antibacterial and growth-promoting additive to animal feed.The development of an effective method for detecting ROX and its conversion products is of importance because of their potential harm to human health and ecosystem.Herein,we report the designed synthesis of a novel one-dimensional covalent organic framework(1D COF),named EP-COF,and its application as a fluorescent probe for ROX sensing.EP-COF is constructed based on imine linkages,exhibiting high crystallinity,strong fluorescence emission,and good dispersibility in water.It displays a remarkable capability to efficiently detect ROX,with an impressive detection limit of 4.5 nmol/L.Moreover,EP-COF also offers advantages of excellent selectivity,and high structural stability.This work not only presents a promising approach for the detection of harmful substances like ROX,but also serves as a valuable reference for exploring application of 1D COFs in chemical sensing.
基金funded by the Minister of Education,Culture,Research,and Technology of Indonesia through a research scheme of“Penelitian Fundamental–Reguler(PFR)2023”under a contract number of 1115c/IT9.2.1/PT.01.03/2023.
文摘This work presents the development of hierarchical niobium pentoxide(Nb_(2)O_(5))-based composite nanofiber membranes for integrated adsorption and photocatalytic degradation of methylene blue(MB)pollutants from aqueous solutions.The Nb_(2)O_(5) nanorods were vertically grown using a hydrothermal process on a base electrospun nanofibrous membrane made of polyacrylonitrile/polyvinylidene fluoride/ammonium niobate(V)oxalate hydrate(Nb_(2)O_(5)@PAN/PVDF/ANO).They were characterized using field-emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD)analysis,and Fourier transform infrared(FTIR)spectroscopy.These composite nanofibers possessed a narrow optical bandgap energy of 3.31 eV and demonstrated an MB degradation efficiency of 96%after 480 min contact time.The pseudo-first-order kinetic study was also conducted,in which Nb_(2)O_(5)@PAN/PVDF/ANO nanofibers have kinetic constant values of 1.29×10^(-2) min^(-1) and 0.30×10^(-2) min^(-1) for adsorption and photocatalytic degradation of MB aqueous solutions,respectively.These values are 17.7 and 7.8 times greater than those of PAN/PVDF/ANO nanofibers without Nb_(2)O_(5) nanostructures.Besides their outstanding photocatalytic performance,the developed membrane materials exhibit advantageous characteristics in recycling,which subsequently widen their practical use in environmental remediation applications.
基金supported by the National Science Foundation grant DMS-1818998.
文摘In this paper,numerical experiments are carried out to investigate the impact of penalty parameters in the numerical traces on the resonance errors of high-order multiscale discontinuous Galerkin(DG)methods(Dong et al.in J Sci Comput 66:321–345,2016;Dong and Wang in J Comput Appl Math 380:1–11,2020)for a one-dimensional stationary Schrödinger equation.Previous work showed that penalty parameters were required to be positive in error analysis,but the methods with zero penalty parameters worked fine in numerical simulations on coarse meshes.In this work,by performing extensive numerical experiments,we discover that zero penalty parameters lead to resonance errors in the multiscale DG methods,and taking positive penalty parameters can effectively reduce resonance errors and make the matrix in the global linear system have better condition numbers.
基金This work was supported by the National Research Foundation of Korea(NRF)grant funded by the Korean Government(MSIT)(2019M3E6A1103944,2020R1A2C2010690).
文摘The unique characteristics of nanofibers in rational electrode design enable effec-tive utilization and maximizing material properties for achieving highly efficient and sustainable CO_(2) reduction reactions( CO_(2)RRs)in solid oxide elec-trolysis cells(SOECs).However,practical appli-cation of nanofiber-based electrodes faces chal-lenges in establishing sufficient interfacial contact and adhesion with the dense electrolyte.To tackle this challenge,a novel hybrid nanofiber electrode,La_(0.6)Sr_(0.4)Co_(0.15)Fe_(0.8)Pd_(0.05)O_(3-δ)(H-LSCFP),is developed by strategically incorporating low aspect ratio crushed LSCFP nanofibers into the excess porous interspace of a high aspect ratio LSCFP nanofiber framework synthesized via electrospinning technique.After consecutive treatment in 100% H_(2) and CO_(2) at 700°C,LSCFP nanofibers form a perovskite phase with in situ exsolved Co metal nanocatalysts and a high concentration of oxygen species on the surface,enhancing CO_(2) adsorption.The SOEC with the H-LSCFP electrode yielded an outstanding current density of 2.2 A cm^(-2) in CO_(2) at 800°C and 1.5 V,setting a new benchmark among reported nanofiber-based electrodes.Digital twinning of the H-LSCFP reveals improved contact adhesion and increased reaction sites for CO_(2)RR.The present work demonstrates a highly catalytically active and robust nanofiber-based fuel electrode with a hybrid structure,paving the way for further advancements and nanofiber applications in CO_(2)-SOECs.
基金National Natural Science Foundation of China(Nos.52225204,52173233 and 52202085)Innovation Program of Shanghai Municipal Education Commission,China(No.2021-01-07-00-03-E00109)+3 种基金Natural Science Foundation of Shanghai,China(No.23ZR1479200)“Shuguang Program”Supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission,China(No.20SG33)Fundamental Research Funds for the Central Universities,China(No.2232024Y-01)DHU Distinguished Young Professor Program,China(Nos.LZA2022001 and LZB2023002)。
文摘Highly dispersed bimetallic alloy nanoparticle electrocatalysts have been demonstrated to exhibit exceptional performance in driving the nitrate reduction reaction(NO_(3)RR)to generate ammonia(NH_(3)).In this study,we prepared mesoporous carbon nanofibers(mCNFs)functionalized with ordered PtFe alloys(O-PtFe-mCNFs)by a composite micelle interface-induced co-assembly method using poly(ethylene oxide)-block-polystyrene(PEO-b-PS)as a template.When employed as electrocatalysts,O-PtFe-mCNFs exhibited superior electrocatalytic performance for the NO_(3RR)compared to the mCNFs functionalized with disordered PtFe alloys(D-PtFe-mCNFs).Notably,the NH_(3)production performance was particularly outstanding,with a maximum NH_(3)yield of up to 959.6μmol/(h·cm~2).Furthermore,the Faraday efficiency(FE)was even 88.0%at-0.4 V vs.reversible hydrogen electrode(RHE).This finding provides compelling evidence of the potential of ordered PtFe alloy catalysts for the electrocatalytic NO_(3)RR.
基金The authors wish to acknowledge financial support from the Science and Technology Projects in Jilin Province Department of Education(Grant No.JJKH20220239KJ).
文摘Copper-based nanomaterials have been widely used in catalysis,electrodes,and other applications due to their unique electron-transfer properties.In this work,an efficient electrochemical sensor based on an electrode modified with one-dimensional Cu(OH)_(2)/carboxymethyl cellulose(CMC)composite nanofibers was fabricated and investigated for the detection of aspirin.Scanning electron microscopy was employed to examine the morphological characteristics of these composite nanofibers.Cyclic voltammetry and electrochemical impedance spectroscopy were used to assess the electrochemical performance of a Cu(OH)_(2)/CMC composite nanofiber-modified electrode.The findings indicate that the modified electrode has a very high sensitivity to aspirin.The observed enhanced performance could be a result of the high surface-to-volume ratio of the composite nanofibers and their superior electron-transport characteristics,which may hasten electron transfer between aspirin and the surfaces of the modified electrode.This detection technique also demonstrated strong selectivity for aspirin.These findings imply that the technique can be applied as a highly effective and selective approach to aspirin measurement in biological science.
基金financially supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.22175007,21975007,52172080,and 22005012)the National Natural Science Foundation for Outstanding Youth Foundation,the Fundamental Research Funds for the Central Universities,the National Program for Support of Top-notch Young Professionalsthe 111 project(Grant No.B14009).
文摘The rational synergy of chemical composition and spatial nanostructures of electrode materials play important roles in high-performance energy storage devices.Here,we designed pea-like MoS_(2)@NiS_(1.03)-carbon hollow nanofibers using a simple electrospinning and thermal treatment method.The hierarchical hollow nanofiber is composed of a nitrogen-doped carbon-coated NiS_(1.03) tube wall,in which pea-like uniformly discrete MoS_(2) nanoparticles are enclosed.As a sodium-ion battery electrode material,the MoS_(2)@NiS_(1.03)-carbon hollow nanofibers have abundant diphasic heterointerfaces,a conductive network,and appropriate volume variation-buffering spaces,which can facilitate ion diffusion kinetics,shorten the diffusion path of electrons/ion,and buffer volume expansion during Na^(+)insertion/extraction.It shows outstanding rate capacity and long-cycle performance in a sodium-ion battery.This heterogeneous hollow nanoarchitectures designing enlightens an efficacious strategy to boost the capacity and long-life stability of sodium storage performance of electrode materials.
基金financial support from projects funded by the National Natural Science Foundation of China(22179017,52172038).
文摘Hydrogen sulfide(H_(2)S)is an industrial exhausted gas that is highly toxic to humans and the environment.Combining desulfurization and fabrication of cathode materials for lithium-sulfur batteries(LSBs)can solve this issue with a double benefit.Herein,the amino-functionalized lotus root-like carbon nanofibers(NH_(2)-PLCNFs)are prepared by the amination of electrospinning carbon nanofibers under dielectric barrier discharge plasma.Selective catalytic oxidation of H_(2)S to elemental sulfur(S)is achieved over the metalfree NH_(2)-PLCNFs catalyst,and the obtained composite S@NH_(2)-PLCNFs is further used as cathode in LSBs.NH_(2)-PLCNFs enable efficient desulfurization(removal capacity as high as 3.46 g H_(2)S g^(−1) catalyst)and strongly covalent stabilization of S on modified carbon nanofibers.LSBs equipped with S@NH_(2)-PLCNFs deliver a high specific capacity of 705.8 mA h g^(−1) at 1 C after 1000 cycles based on the spatial confinement and the covalent stabilization of electroactive materials on amino-functionalized porous carbon matrix.It is revealed that S@NH_(2)-PLCNFs obtained by this kind of chemical vapor deposition leads to a more homogeneous S distribution and superior electrochemical performance to the sample S/NH_(2)-PLCNF-M prepared by the traditional molten infusion.This work opens a new avenue for the combination of environment protection and energy storage.
基金Funded by the Doctoral Fund of Chengdu University (2081919131)the Open Fund of Material Corrosion and Protection Key Laboratory of Sichuan Province (2021CL27)the Sichuan Science and Technology Program (2023YFG0229)。
文摘OER catalyst of Ni_(3)Fe/Ni_(4)S_(3)/Ni/C(NiFeSC series)mixed crystal composite nanofibers was prepared by electrospinning and atmospheric heat treatment process.The testing results indicate that the diameters of Ni_(3)Fe/Ni_(4)S_(3)/Ni/C composite nanofibers is about 200 nm,the grains size is about 1-3 nm,and the fiber surface is rough.The electrochemical test results show that the heterojunction of the prepared Ni_(3)Fe/Ni_(4)S_(3)/Ni/C hybrid crystal composite nanofiber has synergistic effect with sulfide,and exhibits good electrocatalytic activity of water decomposition and OER in alkaline system.The OER electrocatalytic performance of Ni_(3)Fe/Ni_(4)S_(3)/Ni/C composite electrode prepared via a heat treatment at 1000℃process was tested in 1 mol/L KOH electrolytes.The results show that the overpotential is about 298 mV,the Tafel slope is about 74 mV?dec-1,and the surface resistance is about 1.69Ω·cm^(2),at the current density of 10 mA·cm^(-2).
基金supported by Distinguished Youth Talent Program of Fujian Agriculture and Forestry University(xjq201912)the National Natural Science Foundation of China(31801616)+1 种基金Scientific Research Foundation of Hainan Tropical Ocean University(RHDRC202117)Excellent Master Thesis Fund Project of Fujian Agriculture and Forestry University(1122YS01002)。
文摘Recently,food grade nanofiber-based materials have received growing attentions in food packaging.In this work,novel active and intelligent packaging nanofibers based on gelatin/chitosan with curcumin(GA/CS/CUR)were developed via electrospinning technique.Effects of the incorporation of CUR content(0.1%-0.3%,m/m)on the microstructure and functional properties of the electrospun nanofibers were investigated.Morphological studies using scanning electron microscopy indicated that loading CUR can affect the average diameter of nanofiber mats,which remained around 160-180 nm.The addition of an appropriate level CUR(0.2%,m/m)led to a stronger intermolecular interaction,and thus enhanced the thermal stability and tensile strength of the obtained nanofibers.Meanwhile,the incorporation of CUR significantly improved antioxidant activity and the antimicrobial activity of GA/CS/CUR nanofibers.Moreover,the sensitivity of nanofibers to ammonia results indicated that GA/CS nanofibers containing 0.2%CUR(GA/CS/CURⅡ)presented high sensitivity of colorimetric behavior to ammonia(within 3 min).These results suggest GA/CS/CURⅡnanofibers has great potential as a multifunctional packaging to protect and monitor the freshness of proteinrich animal foods,such as meat and seafood.
基金Open Project Program of Key Laboratory of Yarn Materials Forming and Composite Processing Technology of Zhejiang Province,China(No.MTC2020-10)。
文摘Bamboo fibers(BFs),with features of renewability and biodegradability,have been widely used in paper-making products.In order to improve the mechanical properties and water absorption behaviors of the BF paper,bacterial cellulose nanofibers(BCNFs)as environmentally friendly nano-fibrillated cellulose(NFC)were combined with BFs.The structures and properties of the BF/BCNF composite paper were characterized by field emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD),Fourier transforms infrared(FTIR)spectroscopy,mechanical tests,pore size tests,and water absorption tests.The results indicated that the addition of BCNFs could significantly improve the water absorption capacity and mechanical properties.The water absorption ratio of the BF/BCNF composite paper with a BCNF mass fraction of 9%comes to 443%,about 1.33 times that of the pure BF paper.At the same BCNF content,the tensile strength of the BF/BCNF composite paper in dry and wet states was 12.37 MPa and 200.9 kPa,respectively,increasing by 98.24%and 136.91%as compared with that of the BF paper.
基金supported by the National Natural Science Foundation of China,Nos.81974207(to JH),82001383(to DW)the Special Clinical Research Project of Health Profession of Shanghai Municipal Health Commission,No.20204Y0076(to DW)。
文摘Upregulation of vascular endothelial growth factor A/basic fibroblast growth factor(VEGFA/b FGF)expression in the penumbra of cerebral ischemia can increase vascular volume,reduce lesion volume,and enhance neural cell proliferation and differentiation,thereby exerting neuroprotective effects.However,the beneficial effects of endogenous VEGFA/b FGF are limited as their expression is only transiently increased.In this study,we generated multilayered nanofiber membranes loaded with VEGFA/b FGF using layer-by-layer self-assembly and electrospinning techniques.We found that a membrane containing 10 layers had an ideal ultrastructure and could efficiently and stably release growth factors for more than 1 month.This 10-layered nanofiber membrane promoted brain microvascular endothelial cell tube formation and proliferation,inhibited neuronal apoptosis,upregulated the expression of tight junction proteins,and improved the viability of various cellular components of neurovascular units under conditions of oxygen/glucose deprivation.Furthermore,this nanofiber membrane decreased the expression of Janus kinase-2/signal transducer and activator of transcription-3(JAK2/STAT3),Bax/Bcl-2,and cleaved caspase-3.Therefore,this nanofiber membrane exhibits a neuroprotective effect on oxygen/glucose-deprived neurovascular units by inhibiting the JAK2/STAT3 pathway.
基金the National Natural Science Foundation of China(Grant Nos.12004137,62071200,and 12104236)Shandong Provincial Natural Science Foundation of China(Grant Nos.ZR2020QA052,ZR2020ZD28,ZR2021MA040,and ZR2021MA060).
文摘Searching for one-dimensional(1D)nanostructure with ferromagnetic(FM)half-metallicity is of significance for the development of miniature spintronic devices.Here,based on the first-principles calculations,we propose that the 1D CrN nanostructure is a FM half-metal,which can generate the fully spin-polarized current.The ab initio molecular dynamic simulation and the phonon spectrum calculation demonstrate that the 1D CrN nanostructure is thermodynamically stable.The partially occupied Cr-d orbitals endow the nanostructure with FM half-metallicity,in which the half-metallic gap(?s)reaches up to 1.58 eV.The ferromagnetism in the nanostructure is attributed to the superexchange interaction between the magnetic Cr atoms,and a sizable magnetocrystalline anisotropy energy(MAE)is obtained.Moreover,the transverse stretching of nanostructure can effectively modulate?s and MAE,accompanied by the preservation of half-metallicity.A nanocable is designed by encapsulating the CrN nanostructure with a BN nanotube,and the intriguing magnetic and electronic properties of the nanostructure are retained.These novel characteristics render the 1D CrN nanostructure as a compelling candidate for exploiting high-performance spintronic devices.
基金partly supported by the grants(51973027 and 52003044)from the National Natural Science Foundation of Chinathe Fundamental Research Funds for the Central Universities(2232020A-08)+5 种基金International Cooperation Fund of Science and Technology Commission of Shanghai Municipality(21130750100)Major Scientific and Technological Innovation Projects of Shandong Province(2021CXGC011004)supported by the Chang Jiang Scholars Programthe Innovation Program of Shanghai Municipal Education Commission(2019-01-07-00-03-E00023)to Prof.Xiaohong QinYoung Elite Scientists Sponsorship Program by China Association for Science and Technology,State Key Laboratory for Modification of Chemical Fibers and Polymer Materials(KF2216)Donghua University Distinguished Young Professor Program to Prof.Liming Wang。
文摘The degree of polymer chain orientation is a key structural parameter that determines the mechanical and physical properties of fibers.However,understanding and significantly tuning the orientation of fiber macromolecular chains remain elusive.Herein,we propose a novel electrospinning technique that can efficiently modulate molecular chain orientation by controlling the electric field.In contrast to the typical electrospinning method,this technique can piecewise control the electric field by applying high voltage to the metal ring instead of the needle.Benefiting from this change,a new electric field distribution can be realized,leading to a non-monotonic change in the drafting force.As a result,the macromolecular chain orientation of polyethylene oxide(PEO)nanofibers was significantly improved with a recordhigh infrared dichroic ratio.This was further confirmed by the sharp decrease in the PEO jet fineness of approximately 80%and the nanofiber diameter from 298 to 114 nm.Interestingly,the crystallinity can also be adjusted,with an obvious drop from 74.9%to 31.7%,which is different from the high crystallinity caused by oriented chains in common materials.This work guides a new perspective for the preparation of advanced electrospun nanofibers with optimal orientation–crystallinity properties,a merited feature for various applications.
基金supported by the National Natural Science Foundation of China(Nos.52072064,51972051,62171115,and 51732003)the 111 Project(No.B13013).
文摘Photoreforming hydrogen evolution(Pr-HE)of a water-pollutant system could simultaneously achieve efficient hydrogen production and pollutant degradation.It provides a new way to solve energy and environmental issues,but the poor internal charge separation still limits its performance.This work designed hetero-Janus nanofibers(HJNFs)with ordered electric field distribution and separated redox surfaces to promote Pr-HE of the water-pollutant system.Taking ZnO/NiO heterojunction as an example,the hetero-Janus structures were prepared via"Dual-channel"electrospinning and further confirmed by the element morphology analysis and asymmetric distribution of the XPS spectra.The theoretical simulation showed that Janus structures could effectively inhibit the electron trap and hole trap generation,then accelerate the directional carrier migration to the surface.Experimental investigations also confirmed that Janus structures could effectively suppress internal exciton luminescence and accelerate surface charge transfer.The Pr-HE amount and the corresponding propranolol(PRO)degradation rate of HJNFs were 7.9 and 1.5 times higher than hetero-mixed nanofibers(HMNFs).The enhancement factor of Pr-HE in water-PRO to pure water was about 3.1,but nearly zero for HMNFs.This prominent synergistic effect was due to the enhancement of charge separation and the inhibition of cascade side reaction from hetero-Janus structures.Furthermore,the synchronous Pr-HE and degradation reactions were significantly promoted by selective introducing Ag nanoparticles in one side of the HJNFs for enlarging the interfacial Fermi energy level difference.The hetero-Janus strategy offers a new perspective on designing efficient photoreforming photocatalysts for energy and environment applications.
基金the China Scholarship Council(2021)the Deanship of Scientific Research at Northern Border University,Arar,KSA for funding this research work through the project number“NBU-FPEJ-2024-249-03”.
文摘A lightweight flexible thermally stable composite is fabricated by com-bining silica nanofiber membranes(SNM)with MXene@c-MWCNT hybrid film.The flexible SNM with outstanding thermal insulation are prepared from tetraethyl orthosilicate hydrolysis and condensation by electrospinning and high-temperature calcination;the MXene@c-MWCNT_(x:y)films are prepared by vacuum filtration tech-nology.In particular,the SNM and MXene@c-MWCNT_(6:4)as one unit layer(SMC_(1))are bonded together with 5 wt%polyvinyl alcohol(PVA)solution,which exhibits low thermal conductivity(0.066 W m^(-1)K^(-1))and good electromagnetic interference(EMI)shielding performance(average EMI SE_(T),37.8 dB).With the increase in func-tional unit layer,the overall thermal insulation performance of the whole composite film(SMC_(x))remains stable,and EMI shielding performance is greatly improved,especially for SMC_(3)with three unit layers,the average EMI SET is as high as 55.4 dB.In addition,the organic combination of rigid SNM and tough MXene@c-MWCNT_(6:4)makes SMC_(x)exhibit good mechanical tensile strength.Importantly,SMC_(x)exhibit stable EMI shielding and excellent thermal insulation even in extreme heat and cold environment.Therefore,this work provides a novel design idea and important reference value for EMI shielding and thermal insulation components used in extreme environmental protection equipment in the future.
基金This work was financially supported by National Key Research and Development Program(2018YFB1502503).
文摘The oxygen reduction reaction(ORR)electrocatalytic activity of Pt-based catalysts can be significantly improved by supporting Pt and its alloy nanoparticles(NPs)on a porous carbon support with large surface area.However,such catalysts are often obtained by constructing porous carbon support followed by depositing Pt and its alloy NPs inside the pores,in which the migration and agglomeration of Pt NPs are inevitable under harsh operating conditions owing to the relatively weak interaction between NPs and carbon support.Here we develop a facile electrospinning strategy to in-situ prepare small-sized PtZn NPs supported on porous nitrogen-doped carbon nanofibers.Electrochemical results demonstrate that the as-prepared PtZn alloy catalyst exhibits excellent initial ORR activity with a half-wave potential(E_(1/2))of 0.911 V versus reversible hydrogen electrode(vs.RHE)and enhanced durability with only decreasing 11 mV after 30,000 potential cycles,compared to a more significant drop of 24 mV in E_(1/2)of Pt/C catalysts(after 10,000 potential cycling).Such a desirable performance is ascribed to the created triple-phase reaction boundary assisted by the evaporation of Zn and strengthened interaction between nanoparticles and the carbon support,inhibiting the migration and aggregation of NPs during the ORR.