3D core-shell nanofibers framework and functional ceramic nanoparticles synergistically reinforced composite polymer electrolytes for high-performance all-solid-state lithium metal battery

Satisfactory ionic conductivity,excellent mechanical stability,and high-temperature resistance are the prerequisites for the safe application of solid polymer electrolytes(SPEs)in all-solid-state lithium metal batteries(ASSLMBs).In this study,a novel poly(m-phenylene isophthalamide)(PMIA)-core/poly(ethylene oxide)(PEO)-shell nanofiber membrane and the functional Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)ceramic nanopar-ticle are simultaneously introduced into the PEO-based SPEs to prepare composite polymer electrolytes(CPEs).The core PMIA layer of composite nanofibers can greatly improve the mechanical strength and thermal stability of the CPEs,while the shell PEO layer can provide the 3D continuous transport channels for lithium ions.In addition,the introduction of functional LLZTO nanoparticle not only reduces the crys-tallinity of PEO,but also promotes the dissociation of lithium salts and releases more Li^(+)ions through its interaction with the Lewis acid-base of anions,thereby overall improving the transport of lithium ions.Consequently,the optimized CPEs present high ionic conductivity of 1.38×10^(−4)S/cm at 30℃,signifi-cantly improved mechanical strength(8.5 MPa),remarkable thermal stability(without obvious shrinkage at 150℃),and conspicuous Li dendrites blocking ability(>1800 h).The CPEs also both have good com-patibility and cyclic stability with LiFePO_(4)(>2000 cycles)and high-voltage LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811)(>500 cycles)cathodes.In addition,even at low temperature(40℃),the assembled LiFePO4/CPEs/Li bat-tery still can cycle stably.The novel design can provide an effective way to exploit high-performance solid-state electrolytes.

In-situ synthesis of stable perovskite quantum dots in core-shell nanofibers via microfluidic electrospinning

Perovskite quantum dots(PQDs) possess remarkable optical properties, such as tunable photoluminescence(PL) emission spectra, narrow full width at half maximum(FWHM) and high PL quantum yield(QY), endowing the PQDs great application prospects. However, the inherent structural instability of PQDs has seriously hindered the application of PQDs in various photoelectric devices. In this work, a microfluidic electrospinning method was used to fabricate color-tunable fluorescent formamidinium lead halogen(FAPbX_(3), X = Cl, Br, I) PQDs/polymer core-shell nanofiber films. The core-shell spinning nanofiber not only supplies the interspace for the in-situ formation of PQDs, but also significantly reduces the permeability of moisture and oxygen in the air, which greatly improves the stability of PQDs. After adjusting the composition of precursors, the blue-emissive polystyrene(core) and polymethyl methacrylate(shell) coated FAPbCl_(3) QDs(abbreviated as PS/FAPbCl_(3)/PMMA, hereinafter), green-emissive PS/FAPbBr_(3)/PMMA and redemissive PS/FAPbI_(3)/PMMA nanofiber films were fabricated with the highest PL QY of 82.3%. Moreover,the PS/FAPbBr_(3)/PMMA nanofiber film exhibits great PL stability under blue light irradiation, long-term storage in the air and water resistance test. Finally, the green-and red-emissive nanofiber films were directly applied as light conversion films to fabricate wide-color-gamut display with the color gamut of 125%, indicating their tremendous potentials in optoelectronic applications.

Interface Hydrogen-bonded Core-Shell Nanofibers by Coaxial Electrospinning

Core-shell nanofibers were prepared by coaxial electrospinning technology,with poly（ethylene oxide）（PEO） as the core while poly（acrylic acid）（PAA） as the shell.PEO and PAA can form polymer complexes based on hydrogen bonding.In order to avoid forming strong hydrogen bonding complexes at nozzle and blocking spinning process,a polar aprotic solvent,N,N-dimethylformamide（DMF）,was selected to dissolve PEO and PAA respectively.SEM,TEM and DSC were utilized to characterize the morphology and structure of PEO-PAA core-shell nanofibers.FTIR spectra demonstrated that hydrogen bonding was formed at the core-shell interface.In addition,the PAA shell of the nanofibers can be cross-linked by ethylene glycol（EG） under heat treatment,which increases the stability and extends the potential applications in aqueous environment.

Bifunctional TiO_(2-x)nanofibers enhanced gel polymer electrolyte for high performance lithium metal batteries

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.

Fabrication of Core-Shell Hydrogel Bead Based on Sodium Alginate and Chitosan for Methylene Blue Adsorption

A novel core-shell hydrogel bead was fabricated for effective removal of methylene blue dye from aqueous solutions.The core,made of sodium alginate-g-polyacrylamide and attapulgite nanofibers,was cross-linked by Calcium ions(Ca^(2+)).The shell,composed of a chitosan/activated carbon mixture,was then coated onto the core.Fourier transform infrared spectroscopy confirmed the grafting polymerization of acrylamide onto sodium alginate.Scanning electron microscopy images showed the core-shell structure.The core exhibited a high water uptake ratio,facilitating the diffusion of methylene blue into the core.During the diffusion process,the methylene blue was first adsorbed by the shell and then further adsorbed by the core.Adsorption tests showed that the coreshell structure had a larger adsorption capacity than the core alone.The shell effectively enhanced the adsorption capacity to methylene blue compared to the single core.Methylene blue was adsorbed by activated carbon and chitosan in the shell,and the residual methylene blue diffused into the core and was further adsorbed.

Synthesis of Core-shell ZSM-5@ Ordered Mesoporous Silica by Tetradecylamine Surfactant

A core-shell composite consisting of ZSM-5 zeolite as the core and ordered mesoporous silica as the shell was prepared by a surfactant-controlled sol-gel process and using tetradecylamine(TDA) as the template and Tetraethylorthosilicate(TEOS) as the silica precursor.The pores of the silica shell were found to be ordered and perpendicular to the crystal faces of the zeolite core.The thickness of the shell in the coreshell structured composite can be adjusted in the range of 20-90 nm,while the surface morphology and the pore size distribution were modified by changing the mass ratio of TEOS to zeolite.The composite molecular sieves have higher surface area for capturing molecules than ZSM-5,and with the increase of mesoporous shell layer,the ZSM-5@SiO_(2)-x composites show stronger adsorption capacity of butyraldehyde.However,when the shell thickness exceeds 90 nm,the adsorption capacity of butyraldehyde decreases instead.The composites have a huge potential for environmental applications.

Core-Shell Semiconductor-Graphene Nanoarchitectures for Efficient Photocatalysis:State of the Art and Perspectives

Semiconductor photocatalysis holds great promise for renewable energy generation and environment remediation,but generally suffers from the serious drawbacks on light absorption,charge generation and transport,and structural stability that limit the performance.The core-shell semiconductorgraphene(CSSG)nanoarchitectures may address these issues due to their unique structures with exceptional physical and chemical properties.This review explores recent advances of the CSSG nanoarchitectures in the photocatalytic performance.It starts with the classification of the CSSG nanoarchitectures by the dimensionality.Then,the construction methods under internal and external driving forces were introduced and compared with each other.Afterward,the physicochemical properties and photocatalytic applications of these nanoarchitectures were discussed,with a focus on their role in photocatalysis.It ends with a summary and some perspectives on future development of the CSSG nanoarchitectures toward highly efficient photocatalysts with extensive application.By harnessing the synergistic capabilities of the CSSG architectures,we aim to address pressing environmental and energy challenges and drive scientific progress in these fields.

Recent advances in core-shell organic framework-based photocatalysts for energy conversion and environmental remediation

Direct conversion of solar energy into chemical energy in an environmentally friendly manner is one of the most promising strategies to deal with the environmental pollution and energy crisis.Among a variety of materials developed as photocatalysts,the core-shell metal/covalent-organic framework(MOF or COF)photocatalysts have garnered significant attention due to their highly porous structure and the adjustability in both structure and functionality.The existing reviews on core-shell organic framework photocatalytic materials have mainly focused on core-shell MOF materials.However,there is still a lack of indepth reviews specifically addressing the photocatalytic performance of core-shell COFs and MOFs@COFs.Simultaneously,there is an urgent need for a comprehensive review encompassing these three types of core-shell structures.Based on this,this review aims to provide a comprehensive understanding and useful guidelines for the exploration of suitable core-shell organic framework photocatalysts towards appropriate photocatalytic energy conversion and environmental governance.Firstly,the classification,synthesis,formation mechanisms,and reasonable regulation of core-shell organic framework were summarized.Then,the photocatalytic applications of these three kinds of core-shell structures in different areas,such as H_(2)evolution,CO_(2)reduction,and pollutants degradation are emphasized.Finally,the main challenges and development prospects of core-shell organic framework photocatalysts were introduced.This review aims to provide insights into the development of a novel generation of efficient and stable core-shell organic framework materials for energy conversion and environmental remediation.

Amorphous core-shell NiMoP@CuNWs rod-like structure with hydrophilicity feature for efficient hydrogen production in neutral media

Using interface engineering,a highly efficient catalyst with a shell@core structure was successfully synthesized by growing an amorphous material composed of Ni,Mo,and P on Cu nanowires(Ni-MoP@CuNWs).This catalyst only requires an overpotential of 35 mV to reach a current density of 10 mA cm^(-2).The exceptional hydrogen evolution reaction(HER)activity is attributed to the unique amorphous rod-like nature of NiMoP@CuNWs,which possesses a special hydrophilic feature,en-hances mass transfer,promotes effective contact between the electrode and electrolyte solution,and exposes more active sites during the catalytic process.Density functional theory revealed that the introduction of Mo weakens the binding strength of the Ni site on the catalyst surface with the H atom and promotes the desorption process of the H_(2) product significantly.Owing to its facile syn-thesis,low cost,and high catalytic performance,this electrocatalyst is a promising option for com-mercial applications as a water electrolysis catalyst.

A novel Ag/ZnO core-shell structure for efficient sterilization synergizing antibiotics and subsequently removing residuals

The massive use of antibiotics has led to the aggravation of bacterial resistance and also brought environmental pollution problems.This poses a great threat to human health.If the dosage of antibiotics is reduced by increasing its bactericidal performance,the emergence of drug resistance is certainly delayed,so that there's not enough time for developing drug resistance during treatment.Therefore,we selected typical representative materials of metal Ag and semiconductor ZnO nano-bactericides to design and synthesize Ag/ZnO hollow core-shell structures(AZ for short).Antibiotics are grafted on the surface of AZ through rational modification to form a composite sterilization system.The research results show that the antibacterial efficiency of the composite system is significantly increased,from the sum(34.7%+22.8%-57.5%)of the antibacterial efficiency of AZ and gentamicin to 80.2%,net synergizes 22.7%,which fully reflects the effect of 1+1>2.Therefore,the dosage of antibiotics can be drastically reduced in this way,which makes both the possibility of bacterial resistance and medical expenses remarkably decrease.Subsequently,residual antibiotics can be degraded under simple illumination using AZ-self as a photocatalyst,which cuts off the path of environmental pollution.In short,such an innovative route has guiding significance for drug resistance.

Exploring the Core-shell Structure of BaTiO3-based Dielectric Ceramics Using Machine Learning Models and Interpretability Analysis

A machine learning(ML)-based random forest(RF)classification model algorithm was employed to investigate the main factors affecting the formation of the core-shell structure of BaTiO_(3)-based ceramics and their interpretability was analyzed by using Shapley additive explanations(SHAP).An F1-score changed from 0.8795 to 0.9310,accuracy from 0.8450 to 0.9070,precision from 0.8714 to 0.9000,recall from 0.8929 to 0.9643,and ROC/AUC value of 0.97±0.03 was achieved by the RF classification with the optimal set of features containing only 5 features,demonstrating the high accuracy of our model and its high robustness.During the interpretability analysis of the model,it was found that the electronegativity,melting point,and sintering temperature of the dopant contribute highly to the formation of the core-shell structure,and based on these characteristics,specific ranges were delineated and twelve elements were finally obtained that met all the requirements,namely Si,Sc,Mn,Fe,Co,Ni,Pd,Er,Tm,Lu,Pa,and Cm.In the process of exploring the structure of the core-shell,the doping elements can be effectively localized to be selected by choosing the range of features.

Interfacial reinforcement of core-shell HMX@energetic polymer composites featuring enhanced thermal and safety performance

The weak interface interaction and solid-solid phase transition have long been a conundrum for 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane(HMX)-based polymer-bonded explosives(PBX).A two-step strategy that involves the pretreatment of HMX to endow—OH groups on the surface via polyalcohol bonding agent modification and in situ coating with nitrate ester-containing polymer,was proposed to address the problem.Two types of energetic polyether—glycidyl azide polymer(GAP)and nitrate modified GAP(GNP)were grafted onto HMX crystal based on isocyanate addition reaction bridged through neutral polymeric bonding agent(NPBA)layer.The morphology and structure of the HMX-based composites were characterized in detail and the core-shell structure was validated.The grafted polymers obviously enhanced the adhesion force between HMX crystals and fluoropolymer(F2314)binder.Due to the interfacial reinforcement among the components,the two HMX-based composites exhibited a remarkable increment of phase transition peak temperature by 10.2°C and 19.6°C with no more than 1.5%shell content,respectively.Furthermore,the impact and friction sensitivity of the composites decreased significantly as a result of the barrier produced by the grafted polymers.These findings will enhance the future prospects for the interface design of energetic composites aiming to solve the weak interface and safety concerns.

Core-shell mesoporous carbon hollow spheres as Se hosts for advanced Al-Se batteries

Incorporating a selenium(Se)positive electrode into aluminum(Al)-ion batteries is an effective strategy for improving the overall battery performance.However,the cycling stability of Se positive electrodes has challenges due to the dissolution of intermediate reaction products.In this work,we aim to harness the advantages of Se while reducing its limitations by preparing a core-shell mesoporous carbon hollow sphere with a titanium nitride(C@TiN)host to load 63.9wt%Se as the positive electrode material for Al-Se batteries.Using the physical and chemical confinement offered by the hollow mesoporous carbon and TiN,the obtained core-shell mesoporous carbon hollow spheres coated with Se(Se@C@TiN)display superior utilization of the active material and remarkable cycling stability.As a result,Al-Se batteries equipped with the as-prepared Se@C@TiN composite positive electrodes show an initial discharge specific capacity of 377 mAh·g^(-1)at a current density of 1000 mA·g^(-1)while maintaining a discharge specific capacity of 86.0 mAh·g^(-1)over 200 cycles.This improved cycling performance is ascribed to the high electrical conductivity of the core-shell mesoporous carbon hollow spheres and the unique three-dimensional hierarchical architecture of Se@C@TiN.

Integrated adsorption and photocatalytic removal of methylene blue dye from aqueous solution by hierarchical Nb_(2)O_(5)@PAN/PVDF/ANO composite nanofibers

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.

Fe-N_(x) sites coupled with core-shell FeS@C nanoparticles to boost the oxygen catalysis for rechargeable Zn-air batteries

The development of efficient single-atom catalysts(SACs) for the oxygen reduction reaction(ORR)remains a formidable challenge,primarily due to the symmetric charge distribution of metal singleatom sites(M-N_(4)).To address such issue,herein,Fe-N_(x) sites coupled synergistic catalysts fabrication strategy is presented to break the uniform electronic distribution,thus enhancing the intrinsic catalytic activity.Precisely,atomically dispersed Fe-N_(x) sites supported on N/S-doped mesoporous carbon(NSC)coupled with FeS@C core-shell nanoparticles(FAS-NSC@950) is synthesized by a facile hydrothermal reaction and subsequent pyrolysis.Due to the presence of an in situ-grown conductive graphitic layer(shell),the FeS nanoparticles(core) effectively adjust the electronic structure of single-atom Fe sites and facilitate the ORR kinetics via short/long-range coupling interactions.Consequently,FAS-NSC@950displays a more positive half-wave potential(E_(1/2)) of 0.871 V with a significantly boosted ORR kinetics(Tafel slope=52.2 mV dec^(-1)),outpacing the commercial Pt/C(E_(1/2)=0.84 V and Tafel slope=54.6 mV dec^(-1)).As a bifunctional electrocatalyst,it displays a smaller bifunctional activity parameter(ΔE) of 0.673 V,surpassing the Pt/C-RuO_(2) combination(ΔE=0.724 V).Besides,the FAS-NSC@950-based zincair battery(ZAB) displays superior power density,specific capacity,and long-term cycling performance to the Pt/C-Ir/C-based ZAB.This work significantly contributes to the field by offering a promising strategy to enhance the catalytic activity of SACs for ORR,with potential implications for energy conversion and storage technologies.

Synergistic Tuning of Nickel Cobalt Selenide@Nickel Telluride Core-Shell Heteroarchitectures for Boosting Overall Urea Electrooxidation and Electrochemical Supercapattery

Herein,we demonstrate the synthesis of bifunctional nickel cobalt selenide@nickel telluride(Ni_(x)Co_(12-x)Se@NiTe)core-shell heterostructures via an electrodeposition approach for overall urea electrolysis and supercapacitors.The 3D vertically orientated NiTe dendritic frameworks induce the homogeneous nucleation of 2D Ni_(x)Co_(12-x)Se nanosheet arrays along similar crystal directions and bring a strong interfacial binding between the integrated active components.In particular,the optimized Ni_(6)Co_(6)Se@NiTe with an interface coupling effect works in concert to tune the intrinsic activity.It only needs a low overpotential of 1.33 V to yield a current density of 10 mA cm^(-2)for alkaline urea electrolysis.Meanwhile,the full urea catalysis driven only by Ni_(6)Co_(6)Se@NiTe achieves 10 mA cm^(-2)at a potential of 1.38 V and can approach a constant level of the current response for 40 h.Besides,the integrated Ni_(6)Co_(6)Se@NiTe electrode delivers an enhanced specific capacity(223 mA h g^(-1)at 1 A g^(-1))with a high cycling stability.Consequently,a hybrid asymmetric supercapacitor(HASC)device based on Ni_(6)Co_(6)Se@NiTe exhibits a favorable rate capability and reaches a high energy density of 67.7 Wh kg^(-1)and a power density of 724.8 W kg^(-1)with an exceptional capacity retention of 92.4%after sequential 12000 cycles at 5 A g^(-1).

Novel Perovskite Oxide Hybrid Nanofibers Embedded with Nanocatalysts for Highly Efficient and Durable Electrodes in Direct CO_(2) Electrolysis

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.

Mesoporous Carbon Nanofibers Loaded with Ordered PtFe Alloy Nanoparticles for Electrocatalytic Nitrate Reduction to Ammonia

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.

Core-shell structured silk Fibroin/PVDF piezoelectric nanofibers for energy harvesting and self-powered sensing

The development of wearable and portable electronics calls for flexible piezoelectric materials to fabricate selfpowered devices.However,a big challenge in piezoelectric material design is to boost the output performance while ensuring its flexibility and biocompatibility.Here,all-organic and core-shell structured silk fibroin(SF)/poly(vinylidene difluoride)(PVDF)piezoelectric nanofibers(NFs)with excellent flexibility are fabricated using a simple electrospinning strategy.The strong intermolecular interaction between SF and PVDF promotes theβ-phase nucleation in the core-shell structure,which significantly enhances the output performance.An output of 16.5 V was achieved in SF/PVDF NFs,which is more than 6-fold enhancement compared with that of pure PVDF NFs.In addition,the piezoelectric device can sensitively detect the mechanical stimulation from joint bending,demonstrating its great potential in self-powered sensor.Otherwise,the piezoelectric device can be also applied to control the movement of a smart car,successfully,achieving its application in the human-machine interaction.

Efficient microwave absorption achieved through in situ construction of core-shell Co Fe_(2)O_(4)@mesoporous carbon hollow spheres

Cobalt ferrite(CoFe_(2)O_(4)),with good chemical stability and magnetic loss,can be used to prepare composites with a unique structure and high absorption.In this study,CoFe_(2)O_(4)@mesoporous carbon hollow spheres(MCHS)with a core-shell structure were prepared by introducing CoFe_(2)O_(4)magnetic particles into hollow mesoporous carbon through a simple in situ method.Then,the microwave absorption performance of the CoFe_(2)O_(4)@MCHS composites was investigated.Magnetic and dielectric losses can be effectively coordinated by constructing the porous structure and adjusting the ratio of MCHS and CoFe_(2)O_(4).Results show that the impedance matching and absorption properties of the Co Fe_(2)O_(4)@MCHS composites can be altered by tweaking the mass ratio of MCHS and CoFe_(2)O_(4).The minimum reflection loss of the Co Fe_(2)O_(4)@MCHS composites reaches-29.7 dB at 5.8 GHz.In addition,the effective absorption bandwidth is 3.7 GHz,with the thickness being 2.5 mm.The boosted microwave absorption can be ascribed to the porous core-shell structure and introduction of magnetic particles.The coordination between the microporous morphology and the core-shell structure is conducive to improving the attenuation coefficient and achieving good impedance matching.The porous core-shell structure provides large solid-void and CoFe_(2)O_(4)-C interfaces to induce interfacial polarization and extend the electromagnetic waves’multiple scattering and reflection.Furthermore,natural resonance,exchange resonance,and eddy current loss work together for the magnetic loss.This method provides a practical solution to prepare core-shell structure microwave absorbents.